Tropical
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![]() Tropical Cyclone IMELDA Southern Hemisphere Summary |
WTXS21 PGTW 20130405 13:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 155 NM EITHER SIDE OF A LINE FROM 11.2S 75.4E TO 12.3S 67.3E WITHIN THE NEXT 06 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 28 TO 33 KNOTS. METSAT IMAGERY AT 051230Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 11.3S 74.7E. THE SYSTEM IS MOVING WESTWARD AT 12 KNOTS. 2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.7S 78.1E, IS NOW LOCATED NEAR 11.3S 74.7E, APPROXIMATELY 270 NM SOUTH-SOUTHEAST OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS FORMATIVE CONVECTIVE BANDS HAVE FURTHER DEEPENED AND WRAPPED TIGHTER INTO A WELL-DEFINED, ALBEIT PARTIALLY EXPOSED, LOW LEVEL CIRCULATION CENTER (LLCC). A 050638Z SCATTEROMETRY PASS CLEARLY SHOWS A TIGHTER AND MORE SYMMETRIC LLCC WITH 30-KNOT WIND BARBS FEEDING INTO IT FROM THE WESTERN AND SOUTHERN QUADRANTS. UPPER LEVEL ANALYSIS INDICATES THE VERTICAL WIND SHEAR HAS RELAXED AS THE CYCLONE IS NOW MOVING WESTWARD AND IN-PHASE WITH THE UPPER LEVEL WIND FLOW. ADDITIONALLY, WESTWARD AND EQUATORWARD OUTFLOW REMAIN ROBUST. THESE ARE EVIDENT ON RECENT ANIMATED WATER VAPOR IMAGERY. ALONG-TRACK SEA SURFACE TEMPERATURES REMAIN FAVORABLE (28 TO 29 DEGREES CELSIUS) FOR FURTHER DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 MB. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 061300Z. // ========================================================================= WTXS31 PGTW 20130406 09:00z COR MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 001 CORRECTED// REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/051251Z APR 13// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 001B CORRECTED 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 060600Z --- NEAR 10.9S 72.6E MOVEMENT PAST SIX HOURS - 285 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 10.9S 72.6E --- FORECASTS: 12 HRS, VALID AT: 061800Z --- 10.9S 71.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 265 DEG/ 08 KTS --- 24 HRS, VALID AT: 070600Z --- 11.1S 69.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 255 DEG/ 09 KTS --- 36 HRS, VALID AT: 071800Z --- 11.6S 68.0E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 260 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 080600Z --- 12.0S 65.9E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 260 DEG/ 10 KTS --- 72 HRS, VALID AT: 090600Z --- 12.5S 62.0E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 260 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 100600Z --- 13.0S 59.3E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 235 DEG/ 04 KTS --- 120 HRS, VALID AT: 110600Z --- 14.0S 57.9E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 060900Z POSITION NEAR 10.9S 72.3E. TROPICAL CYCLONE (TC) 21S, LOCATED APPROXIMATELY 220 NM SOUTH OF DIEGO GARCIA, HAS TRACKED WEST-NORTHWESTWARD AT 04 KNOTS DURING THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS AN ELONGATED AREA OF DEEP CONVECTION WITH FORMATIVE BANDING WRAPPING INTO AN ILL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). A 060502Z TRMM 37 GHZ IMAGE REVEALS THE ELONGATED NATURE OF THE LLCC AND SUGGESTS THE POSSIBILITY OF MULTIPLE VORTICES. THE INITIAL POSITION IS BASED ON THE AFOREMENTIONED TRMM IMAGE AND POSITION FIXES FROM PGTW AND KNES WITH LOW CONFIDENCE DUE TO THE BROADNESS OF THE CIRCULATION. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES. UPPER LEVEL ANALYSIS INDICATES TC 21S IS JUST EQUATORWARD OF THE SUBTROPICAL RIDGE (STR) AXIS WITH GOOD RADIAL OUTFLOW BEGINNING TO DEVELOP, AS INDICATED BY ANIMATED WATER VAPOR IMAGERY. CONVECTIVE ORGANIZATION IS BEING HAMPERED BY MODERATE (20 KNOTS) VERTICAL WIND SHEAR (VWS). SEA SURFACE TEMPERATURES ARE FAVORABLE AT 29 DEGREE CELSIUS. TC 21S WILL CONTINUE TO TRACK WEST-SOUTHWESTWARD UNDER THE INFLUENCE OF THE DEEP LAYER STR TO THE SOUTH. AS VWS BECOMES MORE FAVORABLE, THE SYSTEM IS FORECAST TO GRADUALLY INTENSIFY TO A PEAK OF 100 KNOTS BY TAU 96. AFTER TAU 96, TC 21S IS EXPECTED TO SLOW AND DEFLECT POLEWARD AS AN APPROACHING MID-LATITUDE TROUGH BEGINS TO BREAKDOWN THE STR. THE AVAILABLE DYNAMICAL MODEL AND ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT WITH THIS FORECAST SCENARIO, HOWEVER, THE OVERALL FORECAST CONFIDENCE IS LOW DUE TO THE DIFFICULTY IN ASSESSING THE INITIAL POSITION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 060600Z IS 10 FEET. NEXT WARNINGS AT 062100Z AND 070900Z. THIS WARNING SUPERSEDES AND CANCELS REF A, JOINT TYPHOON WRNCEN PEARL HARBOR HI 051251Z APR 13 TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 051300). JUSTIFICATION FOR CORRECTION: ADDED MISSING REF AND AMPN LINES TO MESSAGE HEADER AND DELETED THE REPEAT OF GEOGRAPHICAL REFERENCE.// ========================================================================= WTXS31 PGTW 20130406 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 002// RMKS/ 1. TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 002 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 061800Z --- NEAR 10.7S 71.5E MOVEMENT PAST SIX HOURS - 280 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT REPEAT POSIT: 10.7S 71.5E --- FORECASTS: 12 HRS, VALID AT: 070600Z --- 11.0S 70.0E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 255 DEG/ 09 KTS --- 24 HRS, VALID AT: 071800Z --- 11.5S 68.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 260 DEG/ 10 KTS --- 36 HRS, VALID AT: 080600Z --- 11.8S 66.3E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 265 DEG/ 11 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 081800Z --- 12.0S 64.1E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 260 DEG/ 09 KTS --- 72 HRS, VALID AT: 091800Z --- 12.5S 60.6E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 240 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 101800Z --- 13.6S 58.6E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 205 DEG/ 03 KTS --- 120 HRS, VALID AT: 111800Z --- 14.8S 58.0E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 062100Z POSITION NEAR 10.8S 71.1E. TROPICAL CYCLONE (TC) 21S, LOCATED APPROXIMATELY 200 NM SOUTH- SOUTHWEST OF DIEGO GARCIA, HAS TRACKED WESTWARD AT 05 KNOTS DURING THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS PERSISTENT CONVECTION, WHICH BECOMES SHEARED TO THE WEST BY MODERATE VERTICAL WIND SHEAR (VWS) LEAVING THE EASTERN PORTION OF THE LOW- LEVEL CIRCULATION CENTER (LLCC) PARTIALLY-EXPOSED. THE INITIAL POSITION IS BASED ON A 061621Z ASCAT AMBIGUITY ANALYSIS ALONG WITH THE 061707Z AMSU-B, WHICH CORRELATE VERY WELL WITH THE PGTW CENTER FIX, WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES ALONG WITH THE ASCAT PASS. UPPER-LEVEL ANALYSIS INDICATES TC 21S IS APPROXIMATELY 05 DEGREES EQUATORWARD OF THE SUBTROPICAL RIDGE (STR) AXIS AND MODERATE 20-KNOT VWS CONTINUES TO HAMPER THE CONVECTIVE DEVELOPMENT. ANIMATED WATER VAPOR IMAGERY INDICATES GOOD POLEWARD OUTFLOW, HOWEVER EQUATORWARD OUTFLOW IS LIMITED DUE TO TROUGHING NORTH AND EAST OF MADAGASCAR. TC 21S WILL CONTINUE TO TRACK WEST-SOUTHWESTWARD UNDER THE INFLUENCE OF THE DEEP LAYERED STR TO THE SOUTH. BY TAU 48 AN UPPER-LEVEL TROUGH WILL RE-ORIENTATE THE CURRENT WEST-EAST ORIENTATED STR TO A NORTHWEST-SOUTHEAST ORIENTATION. THIS WILL ALLOW VWS TO RELAX AS THE SYSTEM NEARS THE STR AXIS. IN ADDITION, A WARMER POOL OF SEA SURFACE TEMPERATURES AND OCEAN HEAT CONTENT DURING THIS TIME WILL ALLOW TC 21S TO INTENSIFY SOMEWHAT RAPIDLY. FURTHER INTENSIFICATION IS EXPECTED THRU TAUS 72- 96 AS POLEWARD OUTFLOW INCREASES IN RESPONSE TO A DIFFERENT AND DEEPER UPPER-LEVEL TROUGH APPROACHING FROM THE WEST. THIS TROUGH WILL FURTHER BREAK DOWN THE STEERING STR AND ALLOW FOR TC 21S TO DIP POLEWARD TOWARDS THE MID-LATITUDES. THE FORECAST STILL CALLS FOR A PEAK OF 100 KNOTS BY TAU 96 BUT THIS MAY NEED TO BE ADJUSTED AS THE INFLUENCE OF FAVORABLE FACTORS BEGINS TO TAKE THEIR EFFECTS. MODEL GUIDANCE IS IN A GENERAL AGREEMENT WITH THE POLEWARD DEFLECTION IN THE EXTENDED FORECAST HOWEVER THE TIMING AND SHARPNESS IN THE DEFLECTION ARE STILL UNCLEAR. THE WBAR AND EGRR HAVE BEEN SUBJECTIVELY DISCOUNTED DUE TO THEIR ERRONEOUS TRACKS. THE OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS FORECAST BUT THE TAU 120 POSITION DIPS FURTHER POLEWARD THAN PREVIOUSLY FORECAST. THERE IS HIGH CONFIDENCE IN THE THREE DAY FORECAST BUT LOW CONFIDENCE IN THE EXTENDED PORTION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 061800Z IS 11 FEET. NEXT WARNINGS AT 070900Z AND 072100Z.// ========================================================================= WTXS31 PGTW 20130407 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 003// RMKS/ 1. TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 003 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 070600Z --- NEAR 10.6S 70.5E MOVEMENT PAST SIX HOURS - 270 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 10.6S 70.5E --- FORECASTS: 12 HRS, VALID AT: 071800Z --- 10.9S 68.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 260 DEG/ 10 KTS --- 24 HRS, VALID AT: 080600Z --- 11.3S 66.8E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 265 DEG/ 10 KTS --- 36 HRS, VALID AT: 081800Z --- 11.5S 64.7E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 265 DEG/ 09 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 090600Z --- 11.7S 62.9E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 250 DEG/ 05 KTS --- 72 HRS, VALID AT: 100600Z --- 12.4S 61.0E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 215 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 110600Z --- 13.9S 60.0E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 170 DEG/ 04 KTS --- 120 HRS, VALID AT: 120600Z --- 15.6S 60.3E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 070900Z POSITION NEAR 10.7S 70.1E. TROPICAL CYCLONE (TC) 21S (TWENTYONE), LOCATED APPROXIMATELY 230 NM SOUTH-SOUTHWEST OF DIEGO GARCIA, HAS TRACKED WESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) LOCATED TO THE EAST OF PERSISTENT DEEP CONVECTION. A 070305Z SSMIS 37GHZ MICROWAVE IMAGE REVEALS CURVED BANDING WRAPPING INTO AN ELONGATED LLCC. THE INITIAL POSITION IS BASED ON THE AFOREMENTIONED SSMIS IMAGE AS WELL AS PGTW AND KNES FIX CENTERS. THE INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES BETWEEN 30 TO 35 KNOTS FROM PGTW AND KNES, AS WELL AS A 070414Z ASCAT PASS. UPPER LEVEL ANALYSIS INDICATES TC 21S IS APPROXIMATELY FIVE DEGREES EQUATORWARD OF THE SUBTROPICAL RIDGE (STR) AXIS. VERTICAL WIND SHEAR (VWS) REMAINS MODERATE (15-20 KNOTS), CAUSING THE DEEP CONVECTION TO BE SHEARED TO THE WEST. ANIMATED WATER VAPOR IMAGERY DEPICTS MODERATE POLEWARD OUTFLOW, HOWEVER, EQUATORWARD OUTFLOW IS LIMITED DUE TO TROUGHING. TC 21S WILL CONTINUE TO TRACK WEST-SOUTHWESTWARD THROUGH TAU 72 UNDER THE INFLUENCE OF THE DEEP LAYERED STR TO THE SOUTH. A GRADUAL DECREASE IN VWS AND FAIR OUTFLOW WILL ALLOW FOR INTENSIFICATION. ADDITIONALLY, A POOL OF HIGHER OCEAN HEAT CONTENT LOCATED ALONG THE FORECAST TRACK WILL AID IN THIS INTENSIFICATION. AFTER TAU 72, A DEEP LAYER MID-LATITUDE TROUGH WILL MOVE IN FROM THE WEST AND BEGIN TO REORIENT THE STR IN THE NORTH- SOUTH DIRECTION, ALLOWING FOR TC 21S TO TURN POLEWARD. THE FORECAST CALLS FOR A PEAK INTENSITY OF 95 KNOTS BY TAU 96. THOUGH DYNAMICAL MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT WITH THE POLEWARD DEFLECTION IN THE EXTENDED FORECAST, THE TIMING AND SHARPNESS IN THE DEFLECTION ARE STILL UNCLEAR. THIS IS FURTHER EVIDENCED BY INCREASING SPREAD NOTED IN ENSEMBLE MODEL PRODUCTS. THE OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS FORECAST, WITH THE POLEWARD DEFLECTION NOW BECOMING MORE EVIDENT IN THE LATER TAUS. THERE IS HIGH CONFIDENCE IN THE THREE DAY FORECAST, BUT LOW CONFIDENCE IN THE EXTENDED PORTION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 070600Z IS 13 FEET. NEXT WARNINGS AT 072100Z AND 080900Z.// ========================================================================= WTXS31 PGTW 20130407 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 004// RMKS/ 1. TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 004 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 071800Z --- NEAR 11.2S 68.2E MOVEMENT PAST SIX HOURS - 255 DEGREES AT 11 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT REPEAT POSIT: 11.2S 68.2E --- FORECASTS: 12 HRS, VALID AT: 080600Z --- 11.6S 66.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 265 DEG/ 11 KTS --- 24 HRS, VALID AT: 081800Z --- 11.8S 63.8E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 265 DEG/ 10 KTS --- 36 HRS, VALID AT: 090600Z --- 12.0S 61.8E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 245 DEG/ 07 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 091800Z --- 12.6S 60.5E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 215 DEG/ 03 KTS --- 72 HRS, VALID AT: 101800Z --- 13.5S 59.8E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 185 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 111800Z --- 15.0S 59.7E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 155 DEG/ 05 KTS --- 120 HRS, VALID AT: 121800Z --- 16.7S 60.5E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 072100Z POSITION NEAR 11.3S 67.7E. TROPICAL CYCLONE (TC) 21S (TWENTYONE), LOCATED APPROXIMATELY 335 NM SOUTHWEST OF DIEGO GARCIA, HAS TRACKED WEST-SOUTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) LOCATED EAST OF PERSISTENT DEEP CONVECTION. A 071543Z SSMIS 37 GHZ IMAGE SHOWS GOOD LOWER-LEVEL BANDING STRUCTURE OVER THE WESTERN SEMICIRCLE BUT VERY FRAGMENTED AND WEAK BANDS TO THE EAST. A 071740Z ASCAT PASS DEPICTED 35-40 KNOT WINDS OVER THE WESTERN PORTION OF THE LLCC WHICH ARE WRAPPING INTO THE CENTER. THE CURRENT POSITION IS BASED ON THE AFOREMENTIONED IMAGERY WITH FAIR CONFIDENCE. THE CURRENT INTENSITY IS BASED ON THE TIMELY ASCAT PASS. UPPER-LEVEL ANALYSIS INDICATES TC 21S IS APPROXIMATELY FIVE DEGREES EQUATORWARD OF THE SUBTROPICAL RIDGE (STR) AXIS. VERTICAL WIND SHEAR (VWS) REMAINS MODERATE (15-20 KNOTS), CAUSING THE DEEP CONVECTION TO BE SHEARED TO THE WEST. ANIMATED WATER VAPOR IMAGERY DEPICTS MODERATE POLEWARD OUTFLOW; HOWEVER, EQUATORWARD OUTFLOW IS LIMITED DUE TO TROUGHING. TC 21S WILL CONTINUE TO TRACK WEST-SOUTHWESTWARD THROUGH TAU 48 UNDER THE INFLUENCE OF THE DEEP LAYERED STR TO THE SOUTH. A GRADUAL DECREASE IN VWS AND FAIR OUTFLOW WILL ALLOW FOR INTENSIFICATION. ADDITIONALLY, A POOL OF HIGHER OCEAN HEAT CONTENT LOCATED ALONG THE FORECAST TRACK WILL AID IN THIS INTENSIFICATION. AFTER TAU 72, A DEEP LAYER MID-LATITUDE TROUGH WILL MOVE IN FROM THE WEST AND BEGIN TO REORIENT THE STR IN THE NORTH-SOUTH DIRECTION, ALLOWING FOR TC 21S TO TURN POLEWARD. THE FORECAST CALLS FOR A PEAK INTENSITY OF 95 KNOTS BY TAU 96. THOUGH DYNAMICAL MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT WITH THE POLEWARD DEFLECTION IN THE EXTENDED FORECAST, THE TIMING AND SHARPNESS IN THE DEFLECTION ARE STILL UNCLEAR. THIS IS FURTHER EVIDENCED BY INCREASING SPREAD NOTED IN ENSEMBLE MODEL PRODUCTS. THERE IS HIGH CONFIDENCE IN THE THREE DAY FORECAST, BUT LOW CONFIDENCE IN THE EXTENDED PORTION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 071800Z IS 15 FEET. NEXT WARNINGS AT 080900Z AND 082100Z.// ========================================================================= WTXS31 PGTW 20130408 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 21S (TWENTYONE) WARNING NR 005 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 080600Z --- NEAR 10.9S 65.2E MOVEMENT PAST SIX HOURS - 270 DEGREES AT 12 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT REPEAT POSIT: 10.9S 65.2E --- FORECASTS: 12 HRS, VALID AT: 081800Z --- 11.1S 63.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 265 DEG/ 10 KTS --- 24 HRS, VALID AT: 090600Z --- 11.2S 61.0E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 260 DEG/ 07 KTS --- 36 HRS, VALID AT: 091800Z --- 11.5S 59.6E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 250 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 100600Z --- 11.8S 58.8E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 195 DEG/ 03 KTS --- 72 HRS, VALID AT: 110600Z --- 13.1S 58.5E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 170 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 120600Z --- 14.7S 58.8E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 165 DEG/ 04 KTS --- 120 HRS, VALID AT: 130600Z --- 16.4S 59.2E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 080900Z POSITION NEAR 11.0S 64.7E. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 080600Z IS 17 FEET. AT 040806 TROPICAL CYCLONE CENTER LOCATED 489 NM WSW OF DIEGO_GARCIA. NEXT WARNINGS AT 082100Z AND 090900Z. ========================================================================= WTXS31 PGTW 20130408 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 006// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 006 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 081800Z --- NEAR 11.0S 63.4E MOVEMENT PAST SIX HOURS - 265 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT REPEAT POSIT: 11.0S 63.4E --- FORECASTS: 12 HRS, VALID AT: 090600Z --- 11.3S 61.8E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 255 DEG/ 07 KTS --- 24 HRS, VALID AT: 091800Z --- 11.7S 60.4E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 245 DEG/ 06 KTS --- 36 HRS, VALID AT: 100600Z --- 12.2S 59.3E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 205 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 101800Z --- 13.0S 58.9E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 175 DEG/ 04 KTS --- 72 HRS, VALID AT: 111800Z --- 14.6S 59.0E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 165 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 121800Z --- 16.2S 59.4E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 160 DEG/ 05 KTS --- 120 HRS, VALID AT: 131800Z --- 18.2S 60.1E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 082100Z POSITION NEAR 11.1S 63.0E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 755 NM NORTHEAST OF LA REUNION, HAS TRACKED WESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT SATELLITE FIXES FROM PGTW AND KNES AND A 081531Z SSMIS PASS. THE CURRENT INTENSITY OF 45 KNOTS IS SET SLIGHTLY ABOVE A CONSENSUS OF SUBJECTIVE DVORAK ESTIMATES FROM MULTIPLE REPORTING AGENCIES BASED ON STRUCTURE EVIDENT IN MICROWAVE IMAGERY AND HIGHER AUTOMATED INTENSITY ESTIMATES. RECENT ANIMATED INFRARED SATELLITE IMAGERY SHOWS DEEP CONVECTION FLARING OVER A LOW LEVEL CIRCULATION CENTER (LLCC) EVIDENT IN THE AFOREMENTIONED SSMIS PASS. TC 21S LIES SLIGHTLY EQUATORWARD OF AN UPPER-LEVEL RIDGE AXIS, IN AN AREA OF MODERATE EASTERLY VERTICAL WIND SHEAR AND RADIAL OUTFLOW ALOFT. THE SYSTEM IS TRACKING WESTWARD ALONG THE PERIPHERY OF A SUBTROPICAL RIDGE TO THE SOUTH. TC 21S WILL TURN POLEWARD AFTER TAU 36 AS MID-LATITUDE TROUGH APPROACHING FROM THE SOUTHWEST WEAKENS THE STEERING RIDGE. STEADY INTENSIFICATION IS EXPECTED OVER THE NEXT 36 HOURS AS VERTICAL WIND SHEAR RELAXES AND THE CYCLONE PASSES ACROSS WARM WATER. ENHANCED POLEWARD OUTFLOW AFTER TAU 36 WILL RESULT IN A BRIEF PERIOD OF FASTER INTENSIFICATION BEFORE INCREASING WESTERLY VERTICAL WIND SHEAR USHERS IN SLOW WEAKENING. ALTHOUGH DYNAMICAL MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT WITH THIS FORECAST SCENARIO, SPREAD IN THE SHARPNESS OF THE POLEWARD TURN REMAINS. THIS TREND IS ALSO NOTED IN ENSEMBLE MODEL PRODUCTS. BASED ON THIS SPREAD IN THE GUIDANCE, THERE IS DECREASED CONFIDENCE IN THE JTWC FORECAST TRACK AFTER TAU 48. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 081800Z IS 19 FEET. NEXT WARNINGS AT 090900Z AND 092100Z.// ========================================================================= WTXS31 PGTW 20130409 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 007// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 007 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 090600Z --- NEAR 11.6S 61.2E MOVEMENT PAST SIX HOURS - 255 DEGREES AT 13 KTS POSITION ACCURATE TO WITHIN 025 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT REPEAT POSIT: 11.6S 61.2E --- FORECASTS: 12 HRS, VALID AT: 091800Z --- 12.0S 59.7E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 05 KTS --- 24 HRS, VALID AT: 100600Z --- 12.7S 58.9E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 195 DEG/ 04 KTS --- 36 HRS, VALID AT: 101800Z --- 13.4S 58.7E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 170 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 110600Z --- 14.5S 58.9E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 115 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 155 DEG/ 09 KTS --- 72 HRS, VALID AT: 120600Z --- 17.7S 60.3E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 115 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 145 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 130600Z --- 19.9S 62.1E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 115 DEG/ 08 KTS --- 120 HRS, VALID AT: 140600Z --- 21.1S 65.1E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 090900Z POSITION NEAR 11.7S 60.8E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 650 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED WEST-SOUTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. THE INITIAL POSITION IS BASED ON RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY. THE INITIAL INTENSITY IS AVERAGED FROM SUBJECTIVE DVORAK ESTIMATES FROM MULTIPLE REPORTING AGENCIES INCLUDING PGTW, KNES, FMEE, AND FIMP. ANIMATED INFRARED SATELLITE IMAGERY SHOWS DEEPENED CONVECTION OVER A LOW LEVEL CIRCULATION CENTER THAT IS BEGINNING TO FORM INTO AN EYE-LIKE FEATURE. TC 21S LIES SLIGHTLY EQUATORWARD OF AN UPPER-LEVEL RIDGE AXIS, IN AN AREA OF MODERATE (15-20 KNOT) EASTERLY VERTICAL WIND SHEAR (VWS); HOWEVER, ANIMATED WATER VAPOR IMAGERY SHOWS EXCELLENT RADIAL OUTFLOW. THE SYSTEM IS TRACKING WESTWARD ALONG THE PERIPHERY OF A SUBTROPICAL RIDGE TO THE SOUTH. TC 21S WILL TURN POLEWARD AFTER TAU 24 AS A MID-LATITUDE TROUGH APPROACHING FROM THE SOUTHWEST WEAKENS THE STEERING RIDGE. STEADY INTENSIFICATION IS EXPECTED OVER THE NEXT 24 HOURS AS VWS RELAXES AND THE CYCLONE PASSES ACROSS RELATIVELY WARM WATER. ENHANCED POLEWARD OUTFLOW AFTER TAU 24 WILL RESULT IN A BRIEF PERIOD OF FASTER INTENSIFICATION BEFORE INCREASING WESTERLY VWS BEGINS TO ERODE THE SYSTEM. ALTHOUGH DYNAMICAL MODEL GUIDANCE IS IN GENERALLY GOOD AGREEMENT WITH THIS FORECAST SCENARIO, SPREAD IN THE SHARPNESS OF THE POLEWARD TURN REMAINS. EGRR IS THE EXTREME LEFT OUTLIER AND NAVGEMS IS ON THE RIGHT MARGIN OF THE MODEL ENVELOPE. BASED ON THIS SPREAD IN THE GUIDANCE, THERE IS DECREASED CONFIDENCE IN THE JTWC FORECAST TRACK AFTER TAU 36. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 090600Z IS 22 FEET. NEXT WARNINGS AT 092100Z AND 100900Z. REFER TO TROPICAL CYCLONE 22S (TWENTYTWO) WARNINGS (WTXS32 PGTW) FOR TWELVE-HOURLY UPDATES. // ========================================================================= WTXS31 PGTW 20130409 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 008// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 008 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 091800Z --- NEAR 11.6S 59.5E MOVEMENT PAST SIX HOURS - 260 DEGREES AT 07 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT REPEAT POSIT: 11.6S 59.5E --- FORECASTS: 12 HRS, VALID AT: 100600Z --- 12.0S 58.2E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 05 KTS --- 24 HRS, VALID AT: 101800Z --- 12.6S 57.5E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 185 DEG/ 04 KTS --- 36 HRS, VALID AT: 110600Z --- 13.4S 57.4E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 175 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 111800Z --- 14.4S 57.5E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 155 DEG/ 05 KTS --- 72 HRS, VALID AT: 121800Z --- 16.1S 58.3E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 140 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 131800Z --- 17.8S 59.8E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 135 DEG/ 06 KTS --- 120 HRS, VALID AT: 141800Z --- 19.4S 61.6E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 092100Z POSITION NEAR 11.7S 59.2E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 620 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. THE INITIAL POSITION IS BASED ON RECENT SATELLITE FIXES FROM VARIOUS REPORTING AGENCIES AND A 091423Z CORIOLIS IMAGE SHOWING A CLEAR LOW LEVEL CENTER. THE INTENSITY OF 60 KNOTS IS CONSISTENT WITH SUBJECTIVE DVORAK ESTIMATES FROM PGTW, KNES, AND FMEE. TC 21S CONTINUES TO TRACK GENERALLY WESTWARD ALONG THE NORTHERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE TO THE SOUTH. A MIDLATITUDE TROUGH APPROACHING FROM THE SOUTHWEST WILL ERODE AND EVENTUALLY BREAK THE STEERING RIDGE OVER THE NEXT 72 HOURS, INDUCING A POLEWARD TURN FOLLOWED BY SOUTHEASTWARD MOTION IN THE EXTENDED TERM. THE SYSTEM SHOULD STEADILY INTENSIFY THROUGH THE TURN AS VERTICAL WIND SHEAR REMAINS LOW AND POLEWARD OUTFLOW IMPROVES AHEAD OF THE APPROACHING TROUGH. ALTHOUGH DYNAMICAL MODEL GUIDANCE IS IN AGREEMENT WITH THIS FORECAST SCENARIO, SPREAD IN THE SHARPNESS OF THE POLEWARD TURN REMAINS. HOWEVER, THERE IS GENERAL AGREEMENT AMONG THE MODELS THAT TC 21S WILL REMAIN SEPARATED FROM THE BAROCLINIC ZONE THROUGH TAU 120, BEFORE EVENTUALLY BECOMING EXTRATROPICAL AFTER THE CURRENT FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 091800Z IS 21 FEET. NEXT WARNINGS AT 100900Z AND 102100Z. REFER TO TROPICAL CYCLONE 22S (VICTORIA) WARNINGS (WTXS32 PGTW) FOR TWELVE- HOURLY UPDATES.// ========================================================================= WTXS31 PGTW 20130410 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 009// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 009 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 100600Z --- NEAR 12.0S 58.4E MOVEMENT PAST SIX HOURS - 245 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT REPEAT POSIT: 12.0S 58.4E --- FORECASTS: 12 HRS, VALID AT: 101800Z --- 12.5S 57.7E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 105 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 205 DEG/ 03 KTS --- 24 HRS, VALID AT: 110600Z --- 13.1S 57.4E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 180 DEG/ 03 KTS --- 36 HRS, VALID AT: 111800Z --- 13.8S 57.4E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 170 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 120600Z --- 14.7S 57.6E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 160 DEG/ 04 KTS --- 72 HRS, VALID AT: 130600Z --- 16.4S 58.2E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 150 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 140600Z --- 17.7S 59.0E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 135 DEG/ 06 KTS --- 120 HRS, VALID AT: 150600Z --- 19.4S 60.8E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 100900Z POSITION NEAR 12.1S 58.2E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 570 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED WEST-SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS SLOWED DOWN AND BEGAN TO TRACK MORE SOUTH OF WESTWARD AS IT FURTHER DEEPENED. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND FROM A 100451Z AMSU-B MICROWAVE PASS. THE INITIAL INTENSITY IS A CONSENSUS OF SUBJECTIVE DVORAK ESTIMATES FROM PGTW, KNES, AND FMEE. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST TO THE NORTH OF A RIDGE AXIS IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL WIND SHEAR (VWS) AND GOOD RADIAL OUTFLOW. THE CYCLONE IS BEGINNING TO ROUND THE NORTHWEST PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE TO THE SOUTHEAST. A MID-LATITUDE TROUGH APPROACHING FROM THE SOUTHWEST WILL ERODE THE STEERING RIDGE AND CAUSE TC 21S TO TRACK MORE POLEWARD AFTER TAU 24, FOLLOWED BY A SOUTHEASTWARD TRACK IN THE EXTENDED TAUS. THE SYSTEM SHOULD STEADILY INTENSIFY THROUGH THE TURN AS VWS REMAINS LOW AND POLEWARD OUTFLOW IMPROVES AHEAD OF THE APPROACHING TROUGH. ALTHOUGH DYNAMICAL MODEL GUIDANCE IS IN AGREEMENT WITH THIS FORECAST SCENARIO, SPREAD IN THE SHARPNESS OF THE POLEWARD TURN REMAINS. HOWEVER, THERE IS GENERAL AGREEMENT AMONG THE MODELS THAT TC 21S WILL REMAIN SEPARATED FROM THE BAROCLINIC ZONE THROUGH TAU 120, BEFORE EVENTUALLY BECOMING EXTRATROPICAL AFTER THE CURRENT FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 100600Z IS 25 FEET. NEXT WARNINGS AT 102100Z AND 110900Z. REFER TO TROPICAL CYCLONE 22S (VICTORIA) WARNINGS (WTXS32 PGTW) FOR TWELVE-HOURLY UPDATES. // ========================================================================= WTXS31 PGTW 20130410 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 010// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 010 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 101800Z --- NEAR 12.3S 57.8E MOVEMENT PAST SIX HOURS - 245 DEGREES AT 02 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT REPEAT POSIT: 12.3S 57.8E --- FORECASTS: 12 HRS, VALID AT: 110600Z --- 12.8S 57.5E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 195 DEG/ 04 KTS --- 24 HRS, VALID AT: 111800Z --- 13.5S 57.3E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 185 DEG/ 05 KTS --- 36 HRS, VALID AT: 120600Z --- 14.5S 57.2E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 180 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 121800Z --- 15.3S 57.2E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 165 DEG/ 04 KTS --- 72 HRS, VALID AT: 131800Z --- 16.9S 57.7E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 145 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 141800Z --- 18.3S 58.8E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 135 DEG/ 08 KTS --- 120 HRS, VALID AT: 151800Z --- 20.5S 61.0E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 102100Z POSITION NEAR 12.4S 57.7E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 545 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED WEST-SOUTHWESTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS CONTINUED TO SLOW AS A DEEP LAYERED TROUGH PREVIOUSLY LOCATED OVER SOUTHERN AFRICA HAS STARTED TO MOVE INTO THE SOUTHWESTERN INDIAN OCEAN WEAKENING THE WESTERN EXTENT OF THE SUBTROPICAL HIGH (STH) STEERING THE SYSTEM. AS THE SYSTEM HAS SLOWED OVER THE PAST SIX HOURS, THE OVERALL ORGANIZATION HAS IMPROVED WITH DVORAK ESTIMATED FROM PGTW AND KNES REFLECTING THE RECENT INCREASE IN INTENSITY TO 85 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST TO THE NORTH OF A RIDGE AXIS IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL WIND SHEAR (VWS) AND GOOD RADIAL OUTFLOW. THE CYCLONE IS BEGINNING TO ROUND THE NORTHWEST PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE TO THE SOUTHEAST. THE DEEP LAYERED TROUGH IS EXPECTED TO CONTINUE TRACKING EASTWARD, CAUSING A SHIFT IN THE STH, BRINGING TC 21S SOUTHWARD THROUGH TAU 72. BEYOND TAU 72 THE SYSTEM WILL SHIFT TO A SOUTHEASTWARD TRACK AROUND THE SOUTHWESTERN QUADRANT OF THE STH. MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE FORECAST TRACK WITH THE EXCEPTION OF NVGM AND GFDN SHOWING A MORE WESTWARD TRACK BEFORE EVENTUALLY TURNING TO THE SOUTHEAST LIKE THE REMAINDER OF THE OBJECTIVE AIDS. A LACK OF MID- LATITUDE INTERACTION WILL KEEP VERTICAL WIND SHEAR LOW AND AS THE SYSTEM REMAINS OVER FAVORABLE SEA SURFACE TEMPERATURES, TC 21S IS EXPECTED REMAIN AN INTENSE TROPICAL CYCLONE THROUGHOUT THE FORECAST PERIOD. BASED ON THE FAIR AGREEMENT IN MODEL GUIDANCE THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 101800Z IS 28 FEET. NEXT WARNINGS AT 110900Z AND 112100Z. REFER TO TROPICAL CYCLONE 22S (VICTORIA) WARNINGS (WTXS32 PGTW) FOR TWELVE- HOURLY UPDATES.// ========================================================================= WTXS31 PGTW 20130411 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 011// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 011 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 110600Z --- NEAR 12.9S 57.9E MOVEMENT PAST SIX HOURS - 180 DEGREES AT 02 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT REPEAT POSIT: 12.9S 57.9E --- FORECASTS: 12 HRS, VALID AT: 111800Z --- 13.6S 57.8E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 105 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 185 DEG/ 04 KTS --- 24 HRS, VALID AT: 120600Z --- 14.4S 57.7E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 175 DEG/ 04 KTS --- 36 HRS, VALID AT: 121800Z --- 15.2S 57.8E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 170 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 130600Z --- 16.1S 58.0E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 155 DEG/ 05 KTS --- 72 HRS, VALID AT: 140600Z --- 17.8S 58.8E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 140 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 150600Z --- 19.5S 60.3E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 135 DEG/ 08 KTS --- 120 HRS, VALID AT: 160600Z --- 21.7S 62.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL --- REMARKS: 110900Z POSITION NEAR 13.1S 57.9E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 515 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED SOUTHWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS TIGHTLY CURVED SPIRAL BANDING WRAPPING INTO A LOW LEVEL CIRCULATION CENTER. AN 110358Z SSMIS 37GHZ MICROWAVE IMAGE DEPICTS DEEP CONVECTION FAVORING THE EASTERN QUADRANTS IN RESPONSE TO SLIGHTLY INCREASED VERTICAL WIND SHEAR (VWS), HOWEVER THE CENTER REMAINS WELL DEFINED. THE SYSTEM IS NOW QUASI-STATIONARY AS THE STEERING RIDGE TO THE SOUTHEAST IS WEAKENING AND BECOMING RE- ORIENTED IN RESPONSE TO AN APPROACHING DEEP-LAYER TROUGH (DLT). THE INITIAL POSITION IS EXTRAPOLATED FROM THE AFOREMENTIONED SSMIS IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 75 KNOTS BASED ON A RANGE OF DVORAK CURRENT INTENSITY ESTIMATES FROM 65 TO 77 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM HAS A POINT SOURCE OVERHEAD PROVIDING MODERATE RADIAL OUTFLOW, WITH VWS INCREASING SLIGHTLY TO 10 TO 15 KNOTS. TC 21S IS FORECAST TO CONTINUE TRACKING GENERALLY SOUTHWARD THROUGH TAU 48 AS THE STEERING RIDGE BECOMES RE- ESTABLISHED. BEYOND TAU 48 THE SYSTEM WILL SHIFT TO A SOUTHEASTWARD TRACK AS IT ROUNDS THE SOUTHERN PERIPHERY OF THE STEERING RIDGE. MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE FORECAST TRACK, WITH NVGM BEING THE WESTERN-MOST OUTLIER AND EGRR THE EASTERN-MOST. THERE IS ALSO FAIR AGREEMENT WITH THIS SCENARIO IN THE AVAILABLE ENSEMBLE MODEL PRODUCTS. DESPITE THE SLIGHT WEAKENING TREND OVER THE PAST 12 HOURS, FAVORABLE (28 TO 29 DEGREES CELSIUS) SEA SURFACE TEMPERATURES, LOW TO MODERATE VWS, AND ENHANCED OUTFLOW FROM THE DLT SHOULD ALLOW FOR A PERIOD OF SLIGHT RE-INTENSIFICATION THROUGH TAU 48. AFTER THAT TIME, INCREASING INTERACTION WITH MID-LATITUDE WESTERLIES WILL RESULT IN HIGHER VWS, BEGINNING A GRADUAL DISSIPATION OF TC 21S. ALTHOUGH THERE IS SOME VARIABILITY IN THE TRACK SPEEDS AMONG DYNAMICAL MODELS, THEY SUGGEST THAT TC 21S WILL BEGIN TO INTERACT WITH THE BAROCLINIC MID-LATITUDE FLOW AROUND TAU 120. BASED ON THE FAIR AGREEMENT IN MODEL GUIDANCE THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 110600Z IS 30 FEET. NEXT WARNINGS AT 112100Z AND 120900Z. REFER TO TROPICAL CYCLONE 22S (VICTORIA) WARNINGS (WTXS32 PGTW) FOR TWELVE- HOURLY UPDATES. // ========================================================================= WTXS31 PGTW 20130411 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 012// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 012 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 111800Z --- NEAR 13.3S 58.6E MOVEMENT PAST SIX HOURS - 115 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 050 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT REPEAT POSIT: 13.3S 58.6E --- FORECASTS: 12 HRS, VALID AT: 120600Z --- 13.7S 59.0E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 160 DEG/ 04 KTS --- 24 HRS, VALID AT: 121800Z --- 14.5S 59.3E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 170 DEG/ 05 KTS --- 36 HRS, VALID AT: 130600Z --- 15.4S 59.5E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 165 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 131800Z --- 16.6S 59.8E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 05 KTS --- 72 HRS, VALID AT: 141800Z --- 18.1S 61.2E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 135 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 151800Z --- 19.8S 63.0E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 135 DEG/ 06 KTS --- 120 HRS, VALID AT: 161800Z --- 21.6S 65.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL --- REMARKS: 112100Z POSITION NEAR 13.4S 58.7E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 510 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED EAST-SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS CONVECTION NEAR THE CENTER OF THE SYSTEM HAS BEEN SLOWLY WEAKENING OVER THE PAST 12 HOURS WITH A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). UPPER LEVEL ANALYSIS INDICATES A DEVELOPING MID-LATITUDE TROUGH TO THE SOUTHWEST OF THE SYSTEM HAS STARTED TO MITIGATE THE EQUATORWARD OUTFLOW CHANNEL AND IS CREATING LOW TO MODERATE VERTICAL WIND SHEAR (VWS) ALONG THE WESTERN BOUNDARY OF THE LLCC. OVER THE PAST 24 HOURS, THIS SHIFT IN UPPER LEVEL SUPPORT HAS LED TO THE OBSERVED WEAKENING TREND IN DVORAK ESTIMATES FROM PGTW, KNES, FMEE AND FIMP. MODEL GUIDANCE INDICATES THAT THE NEAR EQUATORIAL RIDGE (NER), STEERING TC 21S, WILL BUILD TO THE SOUTHEAST AS A DEEP-LAYERED TROUGH (DLT) TO THE SOUTHEAST WEAKENS AND CONTINUES TO MOVE EASTWARD. BASED ON THE TIMING OF THIS FEATURE AND THE APPROACH OF A SECOND DLT FROM THE SOUTHWEST, THE FORECAST TRACK WILL UNDERGO A WEAKLY DEFINED STAIR-STEP PATH TO THE SOUTHEAST AS THE NER RE-ORIENTS UNDER THE INFLUENCE OF THE TRANSITORY MID- LATITUDE TROUGHS. THE SECOND DLT TO THE SOUTHWEST WILL CONTINUE TRACKING EASTWARD, ALLOWING THE EQUATORWARD OUTFLOW CHANNEL TO RE- ESTABLISH ITSELF, IMPROVING THE OVERALL UPPER LEVEL ENVIRONMENT BY TAU 24. FAVORABLE SEA SURFACE CONDITIONS IN ASSOCIATION WITH IMPROVED OUTFLOW ALOFT WILL ALLOW FOR THE RE-INTENSIFICATION OF THE SYSTEM THROUGH TAU 72. BEYOND TAU 72 INCREASING VWS AND DECREASING SEA SURFACE TEMPERATURES WILL STIFLE FURTHER DEVELOPMENT, LEADING TO A WEAKENING TREND THROUGH THE REMAINDER OF THE FORECAST PERIOD. DUE TO THE CURRENT POOR STEERING ENVIRONMENT AND MODEL GUIDANCE PERSISTING WITH A STRONGER SOUTHERLY TRACK FOR THE PAST 24 HOURS, THERE IS LOW CONFIDENCE IN THE CURRENT TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z IS 28 FEET. NEXT WARNINGS AT 120900Z AND 122100Z. REFER TO TROPICAL CYCLONE 22S (VICTORIA) WARNINGS (WTXS32 PGTW) FOR TWELVE-HOURLY UPDATES.// ========================================================================= WTXS31 PGTW 20130412 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 013// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 013 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 120600Z --- NEAR 14.1S 58.9E MOVEMENT PAST SIX HOURS - 150 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT REPEAT POSIT: 14.1S 58.9E --- FORECASTS: 12 HRS, VALID AT: 121800Z --- 15.0S 59.1E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 170 DEG/ 05 KTS --- 24 HRS, VALID AT: 130600Z --- 15.9S 59.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 095 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 160 DEG/ 05 KTS --- 36 HRS, VALID AT: 131800Z --- 16.8S 59.6E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 150 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 140600Z --- 17.7S 60.1E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 72 HR POSIT: 135 DEG/ 06 KTS --- 72 HRS, VALID AT: 150600Z --- 19.5S 61.9E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 120900Z POSITION NEAR 14.3S 58.9E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 465 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED SOUTH-SOUTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SHALLOW CURVED BANDING WRAPPING INTO A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). SEVERAL RECENT SCATTEROMETRY PASSES INDICATE THAT THE LOW LEVEL CIRCULATION IS STILL WELL DEFINED, WITH NUMEROUS 40-45 KNOT WIND BARBS WITHIN A FAIRLY SYMMETRIC RADIUS. THE INITIAL POSITION IS BASED ON THE MSI AND SCATTEROMETRY WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS BASED ON DVORAK INTENSITY ESTIMATES OF 45 KNOTS FROM ALL FIXING AGENCIES. OVER THE PAST FEW DAYS, INTENSITY GUIDANCE HAS PERSISTENTLY CALLED FOR A SIGNIFICANT RE-DEVELOPMENT OF TC 21S, HOWEVER, THE ENVIRONMENT HAS BECOME INCREASINGLY UNFAVORABLE. THE CURRENT ANALYSIS HAS LEAD TO A CHANGE OF FORECAST PHILOSOPHY THAT NOW SUPPORTS A GRADUAL DISSIPATION OVER THE NEXT 72 HOURS. UPPER LEVEL ANALYSIS INDICATES AN EQUATORWARD EXTENSION OF AN APPROACHING DEEP LAYER TROUGH HAS AMPLIFIED DUE TO AN ANTICYCLONE OVER THE MOZAMBIQUE CHANNEL, AND IS NOW MOVING ALMOST DIRECTLY OVER THE SYSTEM. THE IMPACT OF THE SUBSIDENCE IS CLEARLY SEEN IN THE EROSION OF CONVECTION NOTED IN MSI, AS WELL AS IN ANIMATED WATER VAPOR IMAGERY. THIS AREA OF TROUGHING HAS ALSO CUT OFF NEARLY ALL WESTWARD AND EQUATORWARD OUTFLOW. VERTICAL WIND SHEAR (VWS) CURRENTLY REMAINS LOW TO MODERATE AND SEA SURFACE TEMPERATURES ARE STILL FAVORABLE, HOWEVER THESE FACTORS ARE NOT ENOUGH TO OVERCOME THE EFFECTS OF THE TROUGHING ON THE SYSTEM. MODEL GUIDANCE INDICATES THAT TC 21S WILL MAINTAIN ITS STRUCTURE AND TRACK ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP LAYER NEAR EQUATORIAL RIDGE TO THE EAST. VWS VALUES ARE EXPECTED TO INCREASE AS THE SYSTEM TRACKS POLEWARD, CONTRIBUTING TO THE GRADUAL DISSIPATION BY TAU 72. AS THE SYSTEM DISSIPATES, THE STEERING FLOW WILL BEGIN TO SHIFT TO LOWER LEVELS. SOME MODELS ARE BEGINNING TO SUGGEST THAT THE LLCC COULD BECOME COMPLETELY UNCOUPLED FROM THE UPPER LEVEL FLOW, CAUSING THE REMNANTS OF TC 21S TO TURN BACK TO THE WEST. DUE TO THE LARGE SPREAD IN TRACKS BASED ON THE STORM DEPTH, THERE IS LOW CONFIDENCE IN THE CURRENT TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 120600Z IS 22 FEET. NEXT WARNINGS AT 122100Z AND 130900Z.REFER TO TROPICAL CYCLONE 22S (VICTORIA) WARNINGS (WTXS32 PGTW) FOR TWELVE-HOURLY UPDATES. ========================================================================= WTXS31 PGTW 20130412 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 014// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 014 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 121800Z --- NEAR 15.3S 59.4E MOVEMENT PAST SIX HOURS - 160 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 15.3S 59.4E --- FORECASTS: 12 HRS, VALID AT: 130600Z --- 16.3S 59.6E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 04 KTS --- 24 HRS, VALID AT: 131800Z --- 17.1S 59.8E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 095 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 180 DEG/ 03 KTS --- 36 HRS, VALID AT: 140600Z --- 17.7S 59.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 122100Z POSITION NEAR 15.5S 59.4E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 405 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED SOUTH-SOUTHEASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS THE ASSOCIATED CONVECTION HAS BECOME MORE SHALLOW AND IS NOW DISPLACED 60 NM SOUTHEAST OF A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND ON A 121623Z 37 GHZ SSMI-S MICROWAVE PASS WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON CONGRUENT SUBJECTIVE DVORAK ESTIMATES FROM PGTW, KNES, AND FIMP. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS 10 DEGREES SOUTH OF A RIDGE AXIS IN AN AREA OF LOW TO MODERATE (05-10 KNOT) VERTICAL WIND SHEAR (VWS). ALONG-TRACK SEA SURFACE TEMPERATURES REMAIN FAVORABLE AT 28-30 DEGREES CELSIUS. THESE DYNAMICS ARE, FOR NOW, SUSTAINING THE CONVECTION; HOWEVER, A NARROW MID-LATITUDE TROUGH TO THE WEST IS BEGINNING TO ERODE THE WESTERN RIM OF THE SYSTEM. TC 21S IS EXPECTED TO STRUGGLE IN MAINTAINING ITS STRUCTURE BUT WILL CONTINUE TO TRACK ALONG THE SOUTHWESTERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE TO THE NORTHEAST. VWS VALUES ARE EXPECTED TO INCREASE AS THE SYSTEM TRACKS POLEWARD, CONTRIBUTING TO THE GRADUAL DISSIPATION BY TAU 36. THERE IS A DISTINCT POSSIBILITY THAT THE CYCLONE WILL DISSIPATE SOONER. AS THE SYSTEM WEAKENS, THE STEERING FLOW WILL BEGIN TO SHIFT TO LOWER LEVELS. AVAILABLE NUMERICAL MODEL SHOWS A LARGE SPREAD IN THE TRACKS, THEREFORE, THERE IS LOW CONFIDENCE IN THE CURRENT TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 121800Z IS 18 FEET. NEXT WARNINGS AT 130900Z AND 132100Z. // ========================================================================= WTXS31 PGTW 20130413 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 015// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 015 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 130600Z --- NEAR 16.1S 59.4E MOVEMENT PAST SIX HOURS - 180 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 16.1S 59.4E --- FORECASTS: 12 HRS, VALID AT: 131800Z --- 17.1S 59.5E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 160 DEG/ 04 KTS --- 24 HRS, VALID AT: 140600Z --- 17.9S 59.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 155 DEG/ 05 KTS --- 36 HRS, VALID AT: 141800Z --- 18.8S 60.2E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 48 HR POSIT: 145 DEG/ 07 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 150600Z --- 20.0S 61.1E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 130900Z POSITION NEAR 16.4S 59.4E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 375 NM NORTHEAST OF LA REUNION, HAS TRACKED SOUTHWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS REBUILDING CONVECTION AROUND A DEFINED LOW-LEVEL CIRCULATION WITH THE BULK OF THE DEEP CONVECTION CONFINED TO THE SOUTHERN SEMI- CIRCLE. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND A 130530Z AMSU-B MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON CONGRUENT DVORAK INTENSITY ESTIMATES FROM PGTW, FMEE, AND FIMP, AND IS FURTHER SUPPORTED BY A 130335Z SSMI-S WIND PRODUCT AND A 130531Z ASCAT PASS SHOWING 35 KNOT WINDS IN THE PERIPHERIES OF THE SYSTEM. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS LOCATED SOUTH OF THE SUBTROPICAL RIDGE AXIS IN AN AREA OF LOW (05- 10 KNOT) VERTICAL WIND SHEAR (VWS). ANIMATED WATER VAPOR IMAGERY REVEALS FAVORABLE POLEWARD OUTFLOW WHICH IS BEING AIDED BY AN UPPER- LEVEL LOW NEAR THE WEST COAST OF AUSTRALIA AND THE SUBTROPICAL JET LOCATED JUST SOUTH OF THE SYSTEM. TC 21S IS EXPECTED TO TRACK ALONG THE SOUTHWESTERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE TO THE NORTHEAST AND SLIGHTLY INTENSIFY IN THE NEXT 24 HOURS AS THE FAVORABLE CONDITIONS OF LOW VWS AND GOOD POLEWARD OUTFLOW ARE FORECAST. AFTER TAU 24, INCREASING VWS AHEAD OF A MID-LATITUDE TROUGH APPROACHING FROM THE WEST WILL OFFSET THE FAVORABLE OUTFLOW ALLOWING FOR DISSIPATION BY TAU 48. DYNAMIC MODEL GUIDANCE CONTINUES TO SHOW A LARGE SPREAD IN TRACKS, ALTHOUGH THERE IS A LOOSE AGREEMENT IN A GENERAL SOUTH TO SOUTHEASTWARD TRACK THROUGH THE FORECAST PERIOD. DUE TO THIS, THE CURRENT FORECAST TRACK LIES CLOSE TO MULTI-MODEL CONSENSUS AND FAVORS THE GFS AND ECMWF SOLUTIONS WITH LOW CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 130600Z IS 18 FEET. NEXT WARNINGS AT 132100Z AND 140900Z.// ========================================================================= WTXS31 PGTW 20130413 21:00z COR MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 016// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 016 01 ACTIVE TROPICAL CYCLONE IN SOUTH IO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 131800Z --- NEAR 16.7S 58.7E MOVEMENT PAST SIX HOURS - 250 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 035 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT REPEAT POSIT: 16.7S 58.7E --- FORECASTS: 12 HRS, VALID AT: 140600Z --- 17.1S 58.5E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 04 KTS --- 24 HRS, VALID AT: 141800Z --- 17.9S 58.7E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 150 DEG/ 04 KTS --- 36 HRS, VALID AT: 150600Z --- 18.6S 59.1E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 150 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 151800Z --- 19.2S 59.5E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 72 HR POSIT: 175 DEG/ 03 KTS --- 72 HRS, VALID AT: 161800Z --- 20.2S 59.6E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 132100Z POSITION NEAR 16.8S 58.6E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 315 NM NORTHEAST OF LA REUNION, HAS TRACKED WEST-SOUTHWESTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS A DEEPENED CENTRAL DENSE OVERCAST FEATURE OVER A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER. THIS IS ALSO EVIDENT ON A 131610Z 37 GHZ SSMI-S MICROWAVE PASS. THE INITIAL POSITION IS BASED ON CLOSELY GROUPED AGENCY FIXES AND ON THE ABOVE MICROWAVE IMAGE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS AN AVERAGE OF SUBJECTIVE DVORAK ESTIMATES FROM PGTW, KNES, AND FIMP. UPPER LEVEL ANALYSIS (ULA) INDICATES THE SYSTEM IS BETWEEN TWO RIDGE AXES - ONE TO THE NORTH AND ANOTHER TO THE SOUTH IN AN AREA OF LOW (05-10 KNOT) VERTICAL WIND SHEAR (VWS). TC 21S HAD UNPREDICTABLY TRACKED WEST-SOUTHWESTWARD OVER THE PAST 12 HOURS. FROM THE SAME ULA, THE STEERING RIDGE TO THE EAST WAS NOT SIGNIFICANTLY WEAKENED BY A PASSING MID-LATITUDE TROUGH AS PREVIOUSLY FORECAST. INSTEAD, THE RIDGE WAS DEFORMED INTO A KIDNEY-SHAPED ANTICYCLONE ALONG A MERIDIONAL AXIS. IN RESPONSE TO THIS TRANSFORMATION TO THE STEERING RIDGE, 21S JOGGED WESTWARD. THIS RECENT DEVELOPMENT NECESSITATED A SLIGHT CHANGE IN THE JTWC TRACK FORECAST PHILOSOPHY. TC IMELDA SHOULD REVERT TO A GENERALLY POLEWARD TRAJECTORY BY TAU 12 AFTER IT ROUNDS THE SOUTHERN EDGE OF THE STEERING RIDGE. AFTER TAU 48, A BUILDING SUBTROPICAL RIDGE TO THE SOUTH WILL BEGIN TO DEFLECT THE CYCLONE WESTWARD. THE SYSTEM WILL PEAK INTENSITY OVER THE NEXT 12 HOURS AS GOOD OUTFLOW PERSISTS; AFTERWARDS, INCREASING VWS WILL GRADUALLY WEAKEN AND EVENTUALLY DISSIPATE THE SYSTEM BY TAU 72. THE AVAILABLE NUMERIC GUIDANCE IS WIDELY SPREAD AND LENDS LOW CONFIDENCE TO THE TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 131800Z IS 25 FEET. NEXT WARNINGS AT 140900Z AND 142100Z. JUSTIFICATION FOR CORRECTION: CORRECTED MINOR TYPOGRAPHICAL ERRORS. ========================================================================= WTXS31 PGTW 20130414 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 017// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 017 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 140600Z --- NEAR 17.2S 59.4E MOVEMENT PAST SIX HOURS - 125 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT REPEAT POSIT: 17.2S 59.4E --- FORECASTS: 12 HRS, VALID AT: 141800Z --- 17.9S 60.0E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 140 DEG/ 05 KTS --- 24 HRS, VALID AT: 150600Z --- 18.6S 60.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 140 DEG/ 05 KTS --- 36 HRS, VALID AT: 151800Z --- 19.4S 61.3E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 155 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 160600Z --- 20.0S 61.6E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 230 DEG/ 04 KTS --- 72 HRS, VALID AT: 170600Z --- 21.0S 60.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 140900Z POSITION NEAR 17.4S 59.5E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 325 NM NORTHEAST OF LA REUNION, HAS TRACKED SOUTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS FLARING DEEP CONVECTION ENCIRCLING A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER THAT HAS DEVELOPED INTO A RAGGED EYE OVER THE PAST SIX HOURS. A 140510Z AMSU-B MICROWAVE IMAGE SHOWS A CONCENTRIC RING OF DEEP CONVECTION AROUND A DEFINED MICROWAVE EYE FEATURE. THE INITIAL POSITION IS BASED ON THE AFOREMENTIONED IMAGERY WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 60 KNOTS IS BASED ON AN AVERAGE OF SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM PGTW AND KNES RANGING FROM 55 TO 65 KNOTS. UPPER-LEVEL ANALYSIS INDICATES TC 21S CONTINUES TO HAVE ROBUST POLEWARD OUTFLOW BUT VERTICAL WIND SHEAR (VWS) HAS SLIGHTLY INCREASED TO MODERATE LEVELS (10-20 KNOTS). TC 21S HAS STARTED TO TRACK SOUTHEAST AROUND A BUILDING EXTENSION OF THE NEAR- EQUATORIAL RIDGE (NER) TO THE NORTHEAST. TC 21S WILL CONTINUE ON THIS SOUTHEASTWARD TRACK FOR THE NEXT 36 HOURS AS THE NER REMAINS THE DOMINANT STEERING INFLUENCE. AFTER TAU 36, A SUBTROPICAL RIDGE IS EXPECTED TO BUILD SOUTH OF THE SYSTEM DRIVING TC 21S ON A MORE WESTWARD TRAJECTORY. TC 21S IS EXPECTED TO REACH A PEAK INTENSITY OF 65 KNOTS IN THE NEXT 12 HOURS AS ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE. AFTER TAU 12, FURTHER INCREASING VWS WILL HAMPER THE SYSTEM AND ALLOW FOR DISSIPATION BY TAU 72. WITH THE EXCEPTION OF NAVGEM, WHICH HAS A MORE SOUTHERN TRAJECTORY, DYNAMIC MODEL GUIDANCE GENERALLY AGREES ON A SOUTHEASTWARD TRACK THROUGH TAU 48, WITH VARYING TRACK SPEEDS AND THE EXTENT OF THE WESTWARD TURN AT THE END OF THE FORECAST PERIOD. DUE TO THIS, THE FORECAST TRACK LIES CLOSE TO MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 140600Z IS 28 FEET. NEXT WARNINGS AT 142100Z AND 150900Z.// ========================================================================= WTXS31 PGTW 20130414 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 018// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 018 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 141800Z --- NEAR 18.6S 61.0E MOVEMENT PAST SIX HOURS - 130 DEGREES AT 14 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT REPEAT POSIT: 18.6S 61.0E --- FORECASTS: 12 HRS, VALID AT: 150600Z --- 19.6S 61.6E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 04 KTS --- 24 HRS, VALID AT: 151800Z --- 20.3S 61.8E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 200 DEG/ 03 KTS --- 36 HRS, VALID AT: 160600Z --- 20.8S 61.6E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 230 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 161800Z --- 21.2S 61.1E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 250 DEG/ 06 KTS --- 72 HRS, VALID AT: 171800Z --- 22.0S 58.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 142100Z POSITION NEAR 18.9S 61.1E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 340 NM EAST-NORTHEAST OF LA REUNION, HAS TRACKED SOUTHEASTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES THE SYSTEM HAS SIGNIFICANTLY DEEPENED AND OPENED AND CLOSED AN EYE IN THE PAST 12 HOURS. THE INITIAL INTENSITY IS BASED ON CLOSELY-GROUPED AGENCY FIXES AND LINED UP WELL WITH A CENTRAL WARM SPOT ON A 141558Z SSMI-S MICROWAVE PASS. THE INITIAL INTENSITY IS BASED ON A CONSENSUS OF SUBJECTIVE DVORAK ESTIMATES FROM PGTW, KNES, AND FIMP. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS SOUTH OF A RIDGE AXIS IN AN AREA OF MODERATE (15-20 KNOT) NORTHWESTERLY VERTICAL WIND SHEAR (VWS); HOWEVER, POLEWARD OUTFLOW, WHICH IS ENHANCING THE CONVECTION, REMAINS ROBUST, AS EVIDENCED ON ANIMATED WATER VAPOR IMAGERY. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A NEAR-EQUATORIAL RIDGE AND IS EXPECTED TO RECURVE WESTWARD AFTER TAU 36 AS A BUILDING SUBTROPICAL RIDGE TO THE SOUTH ASSUMES STEERING. AS THE SYSTEM CONTINUES TO MOVE POLEWARD, THE VWS WILL STEADILY INCREASE CAUSING ITS GRADUAL EROSION AND, FINALLY, DISSIPATION BY TAU 72. THE AVAILABLE NUMERIC GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH WBAR AS THE SOLE OUTLIER EXTENDING THE TRACK SOUTHEASTWARD BEYOND 72 HOURS. THE REMAINDER OF THE MODELS RECURVE THE VORTEX WESTWARD, ALBEIT AT VARYING INCREMENTS. THE JTWC TRACK FORECAST IS LAID CLOSELY TO MODEL CONSENSUS WITH HIGH CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 141800Z IS 32 FEET. NEXT WARNINGS AT 150900Z AND 152100Z. // ========================================================================= WTXS31 PGTW 20130415 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 019// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 019 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 150600Z --- NEAR 19.6S 61.8E MOVEMENT PAST SIX HOURS - 155 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT REPEAT POSIT: 19.6S 61.8E --- FORECASTS: 12 HRS, VALID AT: 151800Z --- 20.5S 62.3E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 180 DEG/ 04 KTS --- 24 HRS, VALID AT: 160600Z --- 21.2S 62.3E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 230 DEG/ 02 KTS --- 36 HRS, VALID AT: 161800Z --- 21.5S 61.9E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 255 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 170600Z --- 21.8S 60.8E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 72 HR POSIT: 260 DEG/ 10 KTS --- 72 HRS, VALID AT: 180600Z --- 22.6S 56.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 150900Z POSITION NEAR 19.8S 61.9E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 360 NM EAST-NORTHEAST OF LA REUNION, HAS TRACKED SOUTH-SOUTHEASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A LARGE COLD DENSE OVERCAST (CDO) FEATURE THAT IS OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC) WHILE THE OVERALL STRUCTURE OF THE SYSTEM IS BECOMING ELONGATED. A 150450Z AMSU-B MICROWAVE IMAGE CONCURS WITH THE MSI AND ADDITIONALLY SHOWS THE CONVECTION SURROUNDING THE LLCC IS BEGINNING TO WEAKEN. THE INITIAL POSITION IS POSITIONED WITH LOW CONFIDENCE DUE TO THE CDO FEATURE OBSCURING THE LLCC AND IS EXTRAPOLATED FROM THE AFOREMENTIONED MICROWAVE IMAGE. THE INITIAL INTENSITY OF 65 KNOTS IS BASED ON CONGRUENT DVORAK INTENSITY ESTIMATES OF THE SAME VALUE FROM ALL REPORTING AGENCIES AND IS CONCURRENT WITH THE OVERALL WEAKENING STRUCTURE. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS SOUTH OF A RIDGE AXIS IN AN AREA OF MODERATE (15-20 KNOT) NORTHWESTERLY VERTICAL WIND SHEAR (VWS) AND POLEWARD OUTFLOW CONTINUES TO BE FAVORABLE AS THE SUBTROPICAL JET JUST SOUTH OF THE SYSTEM, PROVIDES ENHANCEMENT. TC 21S IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF AN EXTENSION OF THE NEAR-EQUATORIAL RIDGE AND IS EXPECTED TO SLOW AND RECURVE WESTWARD AFTER TAU 24 AS A BUILDING SUBTROPICAL RIDGE TO THE SOUTH ASSUMES STEERING. THE SYSTEM SHOULD CONTINUE TO WEAKEN THROUGH THE FORECAST PERIOD AS TC 21S ENCOUNTERS INCREASING VWS, ALLOWING FOR DISSIPATION BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE WESTWARD TRACK, ALTHOUGH WITH VARYING TRACK SPEEDS. THE OFFICIAL FORECAST IS POSITIONED CLOSE TO MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 150600Z IS 28 FEET. NEXT WARNINGS AT 152100Z AND 160900Z.// ========================================================================= WTXS31 PGTW 20130415 21:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 020// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 020 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 151800Z --- NEAR 20.4S 62.2E MOVEMENT PAST SIX HOURS - 160 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT REPEAT POSIT: 20.4S 62.2E --- FORECASTS: 12 HRS, VALID AT: 160600Z --- 21.1S 62.2E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 03 KTS --- 24 HRS, VALID AT: 161800Z --- 21.5S 61.7E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 250 DEG/ 06 KTS --- 36 HRS, VALID AT: 170600Z --- 21.9S 60.5E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 48 HR POSIT: 255 DEG/ 09 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 171800Z --- 22.3S 58.6E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 152100Z POSITION NEAR 20.6S 62.2E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 370 NM EAST OF LA REUNION, HAS TRACKED SOUTH-SOUTHEASTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS RAPIDLY DECAYING DEEP CONVECTION, NOW SHEARED ABOUT 70 NM EAST OF THE SYSTEM CENTER. A 151545Z SSMIS IMAGE DEPICTS WELL-DEFINED, TIGHTLY-WRAPPED SHALLOW CONVECTIVE BANDING WRAPPING INTO THE LOW- LEVEL CIRCULATION CENTER WITH AN ISOLATED AREA OF DEEP CONVECTION NEAR 20S 64E. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THIS IMAGE AS WELL AS A 151719Z AMSU COMPOSITE IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM 45 TO 65 KNOTS. TC 21S IS CURRENTLY TRACKING SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE BUT IS FORECAST TO TURN WESTWARD AS IT WEAKENS AND BEGINS TO STEER UNDER THE INFLUENCE OF A BROAD, TRANSITORY MIDLATITUDE RIDGE BUILDING TO THE SOUTH. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. THE SYSTEM IS EXPECTED TO WEAKEN THROUGH THE FORECAST PERIOD DUE TO PERSISTENT MODERATE TO STRONG VERTICAL WIND SHEAR ASSOCIATED WITH SUBTROPICAL WESTERLY FLOW, AND MARGINAL SST VALUES NEAR 26C. SURFACE WINDS OVER THE SOUTHERN SEMI-CIRCLE ARE FORECAST TO REMAIN NEAR GALE-FORCE LEVELS DUE TO THE ENHANCED GRADIENT ASSOCIATED WITH THE AFOREMENTIONED HIGH BUILDING SOUTH OF THE SYSTEM. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 151800Z IS 22 FEET. NEXT WARNINGS AT 160900Z AND 162100Z.// ========================================================================= WTXS31 PGTW 20130416 09:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (IMELDA) WARNING NR 021// RMKS/ 1. TROPICAL CYCLONE 21S (IMELDA) WARNING NR 021 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 160600Z --- NEAR 21.0S 62.9E MOVEMENT PAST SIX HOURS - 135 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER REPEAT POSIT: 21.0S 62.9E --- FORECASTS: 12 HRS, VALID AT: 161800Z --- 21.7S 63.0E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 160900Z POSITION NEAR 21.2S 62.9E. TROPICAL CYCLONE (TC) 21S (IMELDA), LOCATED APPROXIMATELY 410 NM EAST OF LA REUNION, HAS TRACKED SOUTHEASTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) REMAINS, BUT WITH NO DEEP CONVECTION OVER THE PAST 12 HOURS. A RECENT 160431Z ASCAT PASS REVEALS CENTRAL WINDS BETWEEN 25 TO 35 KNOTS. THE CURRENT INTENSITY HAS BEEN KEPT ON THE HIGH SIDE OF THE SCATTEROMETRY DATA. RECENT OBSERVATIONS FROM PLAINE CORAIL, MAURITIUS INDICATE WIND SPEEDS HAVE BEEN AROUND 20 KNOTS OVER THE PAST SIX HOURS, SUPPORTING THE WEAKENING TREND OF THE LLCC. UPPER LEVEL ANALYSIS INDICATES INCREASING VERTICAL WIND SHEAR (VWS), CURRENTLY AT HIGH LEVELS (GREATER THAN 30 KNOTS), HAS BEEN DIRECTLY IMPACTING THE SYSTEM. IN ASSOCIATION WITH MARGINAL SEA SURFACE TEMPERATURES (SST), THE VWS HAS LED TC 21S TO RAPIDLY WEAKEN FROM THE PREVIOUS FORECAST. MODEL GUIDANCE INDICATES THE VWS AND SST VALUES WILL REMAIN UNFAVORABLE UNTIL THE SYSTEM COMPLETELY DISSIPATES. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 160600Z IS 21 FEET.//
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Document: tropical_cyclone_imelda.htm | Updated: 2 May 2013 |