Tropical
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![]() Tropical Cyclone GRANT Southern Hemisphere Summary |
WTXS21 PGTW 20111224 02:30z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE FORMATION ALERT// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN A 100 NM RADIUS OF 11.0S 131.4E WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CY- CLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IMAGERY, SYNOPTIC DATA AND RADAR DATA AT 232330Z INDICATE THAT A CIRCULATION CENTER IS LOCATED NEAR 11.0S 131.4E. THE SYSTEM IS QUASI-STATIONARY AT 00 KNOTS. 2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.1S 130.6E, IS NOW LOCATED NEAR 11.0S 131.4E, APPROXIMATELY 95 NM NORTH-NORTHEAST OF DARWIN, AUSTRALIA. ANIMATED INFRARED SATELLITE IMAGERY SHOWS SCATTERED POCKETS OF DEEP AND PERSISTENT CONVECTION SURROUNDING A BROAD LOW LEVEL CIRCULATION CENTER (LLCC) EMBEDDED IN THE MONSOON TROUGH. TOTAL PRECIPITABLE WATER LOOPS REVEAL ABUNDANT DEEP MOISTURE FLOWING INTO AND CONSOLIDATING AROUND THE LLCC. THE SYSTEM HAS BEEN MEANDERING JUST OFF-SHORE OF THE TOP END UNDER A WEAK STEERING ENVIRONMENT AND DEVELOPING VERY SLOWLY. THE SCATTERED POCKETS OF CONVECTION APPEAR TO BE SLOWING DEVELOPMENT. HOWEVER, 24 HOUR PRESSURE FALLS FROM SURFACE STATIONS ALONG THE TOP END AND AN OVERALL INCREASE IN THE AMOUNT OF CONVECTION DURING THE PAST 24 HOURS DO INDICATE THAT THE SYSTEM IS DEEPENING. STREAMLINE ANALYSIS REVEALS A SINGULAR POINT AND HIGHLY DIFFLUENT FLOW JUST EAST OF THE SYSTEM. VERTICAL WIND SHEAR IS LESS THAN 10 KNOTS AND SEA SURFACE TEMPERATES ARE 30 TO 32 DEGREES. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 999 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 250230Z. ========================================================================= WTXS31 PGTW 20111225 03:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 03S (GRANT) WARNING NR 001// REF/A/NAVMARFCSTCEN PEARL HARBOR HI/240221ZDEC2011// AMPN/TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. TROPICAL CYCLONE 03S (GRANT) WARNING NR 001 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 250000Z --- NEAR 10.7S 132.7E MOVEMENT PAST SIX HOURS - 060 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, RADAR AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT REPEAT POSIT: 10.7S 132.7E --- FORECASTS: 12 HRS, VALID AT: 251200Z --- 11.4S 132.6E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 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 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 04 KTS --- 24 HRS, VALID AT: 260000Z --- 12.2S 132.8E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 165 DEG/ 04 KTS --- 36 HRS, VALID AT: 261200Z --- 12.9S 133.0E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 110 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 270000Z --- 13.2S 133.8E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 100 DEG/ 05 KTS --- 72 HRS, VALID AT: 280000Z --- 13.5S 136.0E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 090 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 290000Z --- 13.5S 138.7E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 100 DEG/ 07 KTS --- 120 HRS, VALID AT: 300000Z --- 14.0S 141.6E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 250300Z POSITION NEAR 10.9S 132.7E. TROPICAL CYCLONE (TC) 03S (GRANT), LOCATED APPROXIMATELY 150 NM NORTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED NORTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY OVER THE PAST 12 HOURS REVEALS SUBSTANTIAL CONSOLIDATION OF THE CONVECTION AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). THE DAY'S FIRST FRAMES OF ANIMATED MULTISPECTRAL IMAGERY SHOW NUMEROUS OVER-SHOOTING TOPS WITH DEEP, VIGOROUS CONVECTION MASSING NEAR THE SYSTEM CORE. THE LATEST AMSU-B RADIAL CROSS SECTION VERIFIES THE DEVELOPMENT OF A WARM MID- LEVEL ANOMALY OVER THE TOP OF THE SYSTEM. THE CURRENT INTENSITY IS BASED ON A COMBINATION OF DVORAK ASSESSMENTS OF 45 KNOTS FROM PGTW, 35 KNOTS FROM ADRM, 30 KNOTS FROM KNES, AND SURFACE REPORTS FROM MCCLUER ISLAND AND BLACK POINT. DESPITE THE VARIATION IN ASSESSMENTS, OBSERVATIONS ALONG THE TOP END DURING THE PAST 12 HOURS CONFIRM THAT TC 03S IS REALLY RAMPING UP. ANIMATED WATER VAPOR IMAGERY SHOWS EXCELLENT ZONAL OUTFLOW AS WELL AS SOME MINOR IMPINGEMENT OVER THE FAR SOUTHWESTERN QUADRANT. THE 241200Z PGTW STREAMLINE ANALYSIS REVEALS A POINT SOURCE DIRECTLY OVER THE SYSTEM, SO OUTFLOW IS MORE THAN ADEQUATE. VERTICAL WIND SHEAR IS LESS THAN 10 KNOTS AND SEA SURFACE TEMPERATURE IN THE REGION IS 31 TO 32 DEGREES. IN THE AGGREGATE, CONDITIONS FOR FURTHER DEVELOPMENT ARE HIGHLY FAVORABLE AND THE ONLY IMPEDIMENT TO FURTHER DEVELOPMENT IS LAND. THE STEERING ENVIRONMENT REMAINS WEAK AND FICKLE. WITH EACH SUCCESSIVE RUN, HOWEVER, MODEL GUIDANCE HAS GAINED A BETTER HANDLE ON THE PATTERN AND HAS GRADUALLY CAME INTO BETTER ALIGNMENT. THERE ARE STILL OUTLIERS, HOWEVER, WHICH ARE SKEWING CONSENSUS. TC GRANT IS MEANDERING BETWEEN A MID-LEVEL RIDGE OVER THE CONTINENT AND THE WESTERLIES ASSOCIATED WITH THE MONSOON TROUGH ON THE EQUATORWARD SIDE. A WEST-WIND BURST ASSOCIATED WITH THE MADDEN-JULIAN OSCILLATION IS INTENSIFYING THE WESTERLIES, ADDING TO THE BOUNDARY LAYER VORTICITY. ANIMATED WATER VAPOR IMAGERY REVEALS SOME SUBTLE WEAKENING IN THE CONTINENTAL RIDGE AS A WEAK MID-LATITUDE SHORT-WAVE TROUGH MOVES INTO ITS SOUTHWESTERN FLANK. THE RIDGE IS ANCHORED IN AN ANTICYCLONE OVER THE NORTHWEST BASIN, WHICH WILL WEAKEN AND PULL SEAWARD AS THE SHORT WAVE WASHES OVER IT. AS THE RIDGE RETRACTS, IT WILL OPEN A GAP TOWARDS THE SOUTHEAST. TC GRANT WILL TRACK ALONG THAT PATH OF LEAST RESISTANCE, MOVING INLAND NEAR TAU 15, AND THEN WEAKEN AS IT TRACKS ACROSS THE TOP END. DESPITE THE OVERLAND TRACK, HIGH ATMOSPHERIC MOISTURE CONTENT OVER THE TOP END WILL ALLOW THE LLCC TO REMAIN INTACT UNTIL IT EJECTS INTO THE GULF OF CARPENTARIA. ALTHOUGH THE AMBIGUITY IN THE STEERING ENVIRONMENT AND THE OVER-LAND TRACK MAKE FOR CONSIDERABLE UNCERTAINTY IN THE MID-RANGE, IT IS CERTAIN THAT ONCE THE LLCC ENTERS THE GULF OF CARPENTARIA, IT WILL ENCOUNTER VERY FERTILE GROUNDS FOR RE-INTENSIFICATION. BECAUSE CONSENSUS IS BEING SLOWED AND PULLED POLEWARD BY THE ERRONEOUS INFLUENCES OF GFDN AND WBAR, THE TRACK FORECAST STAYS CLOSER TO ECMWF THAN CONSENSUS, ALTHOUGH IT DOES STAY BETWEEN THE TWO. INTENSITY GUIDANCE HAS ALSO COME INTO BETTER ALIGNMENT, INDICATING AN INTENSITY NEAR 50 KNOTS PRIOR TO LANDFALL.MAXIMUM SIGNIFICANT WAVE HEIGHT AT 250000Z IS 12 FEET. NEXT WARNINGS AT 251500Z AND 260300Z. THIS WARNING SUPERSEDES AND CANCELS REF A, NAVMARFCSTCEN 240221Z DEC 11 TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 240230).// ========================================================================= WTXS31 PGTW 20111225 15:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 03S (GRANT) WARNING NR 002// RMKS/ 1. TROPICAL CYCLONE 03S (GRANT) 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: 251200Z --- NEAR 11.5S 132.8E MOVEMENT PAST SIX HOURS - 165 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 11.5S 132.8E --- FORECASTS: 12 HRS, VALID AT: 260000Z --- 12.2S 133.0E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 150 DEG/ 04 KTS --- 24 HRS, VALID AT: 261200Z --- 12.9S 133.4E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 130 DEG/ 04 KTS --- 36 HRS, VALID AT: 270000Z --- 13.4S 134.0E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 100 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 271200Z --- 13.6S 135.0E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 095 DEG/ 05 KTS --- 72 HRS, VALID AT: 281200Z --- 13.7S 137.2E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 96 HR POSIT: 090 DEG/ 08 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 291200Z --- 13.8S 140.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 095 DEG/ 10 KTS --- 120 HRS, VALID AT: 301200Z --- 14.1S 144.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 251500Z POSITION NEAR 11.7S 132.8E. TROPICAL CYCLONE (TC) 03S (GRANT), LOCATED APPROXIMATELY 125 NM EAST-NORTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED SOUTH-SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS JUST MADE LANDFALL NEAR THE BASE OF COBOURG PENINSULA. THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION AND FROM A 251113Z SSMIS MICROWAVE IMAGE SHOWING A DISTINCT CONCAVE BAND AROUND THE LOW LEVEL CIRCULATION CENTER. THIS POSITION WAS ALSO SUPPORTED BY RADAR REFLECTIVITY LOOP FROM DARWIN. THE INITIAL INTENSITY WAS BASED ON THE DVORAK ESTIMATE FROM PGTW AND EXTRAPOLATED FROM NEARBY SURFACE OBSERVATIONS. UPPER LEVEL ANALYSIS INDICATES TC 03S IS UNDERNEATH A RIDGE AXIS IN AN AREA OF LIGHT (05- 10 KNOT) VERTICAL WIND SHEAR. THE SYSTEM IS BEING STEERED BY A LOW- TO MID-LAYERED NEAR-EQUATORIAL RIDGE TO THE NORTHEAST AND IS EXPECTED TO WEAKEN AS IT TRACKS OVER LAND DURING THE NEXT 48 HOURS. HOWEVER, WARM MOIST AIR FROM THE ARAFURA SEA WILL KEEP IT FROM TOTALLY DISSIPATING. THE STEERING RIDGE IS EXPECTED TO BUILD AND EXTEND WESTWARD CAUSING THE CYCLONE TO TRACK ON A MORE EASTWARD TRAJECTORY AFTER TAU 36, EMERGING AND REINTENSIFYING IN THE GULF OF CARPENTARIA BY TAU 72. THE AVAILABLE NUMERICAL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THE EXCEPTION OF GFDN THAT TAKES THE VORTEX ON A SOUTHWEST TRACK. THIS FORECAST IS WITH THE REMAINDER OF THE TRACK ENVELOPE BUT JUST TO THE LEFT OF CONSENSUS TO OFFSET GFDN. NEXT WARNINGS AT 260300Z AND 261500Z.// ========================================================================= WTXS31 PGTW 20111226 03:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 03S (GRANT) WARNING NR 003// RMKS/ 1. TROPICAL CYCLONE 03S (GRANT) 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: 260000Z --- NEAR 13.1S 132.7E MOVEMENT PAST SIX HOURS - 180 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, RADAR AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 13.1S 132.7E --- FORECASTS: 12 HRS, VALID AT: 261200Z --- 14.0S 133.0E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 125 DEG/ 04 KTS --- 24 HRS, VALID AT: 270000Z --- 14.5S 133.7E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 095 DEG/ 07 KTS --- 36 HRS, VALID AT: 271200Z --- 14.6S 135.2E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 095 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 280000Z --- 14.7S 136.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 095 DEG/ 10 KTS --- 72 HRS, VALID AT: 290000Z --- 14.9S 140.9E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 090 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 300000Z --- 14.8S 143.7E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 100 DEG/ 07 KTS --- 120 HRS, VALID AT: 310000Z --- 15.2S 146.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 260300Z POSITION NEAR 13.3S 132.8E. TROPICAL CYCLONE (TC) 03S (GRANT), LOCATED APPROXIMATELY 105 NM EAST-SOUTHEAST OF DARWIN, AUSTRALIA, HAD TRACKED SOUTHWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS WANING CONVECTION OVER THE LOW-LEVEL CIRCULATION CENTER (LLCC) AS IT CONTINUES TO TRACK OVERLAND. THE CURRENT POSITION IS BASED ON A CONGLOMERATE OF RADAR CENTER FIXES, A 252226Z TRMM 85 GHZ IMAGE, A 260033Z AMSU 89 GHZ IMAGE, AND SYNOPTIC OBSERVATIONS FROM THE AREA, WITH GOOD CONFIDENCE. THE CURRENT INTENSITY IS BASED ON THE SYNOPTIC OBSERVATIONS AND INTERPOLATION OF THE MICROWAVE DATA. UPPER-LEVEL ANALYSIS INDICATES THAT TC 03S IS UNDER CONVERGENT WESTERLY FLOW WHICH IS HINDERING THE DIVERGENCE. TC GRANT IS CURRENTLY BEING STEERED BY THE LOW-LEVEL NORTHWEST MONSOON FLOW AND SHOULD CONTINUE GENERALLY EASTWARDS TOWARDS THE GULF OF CARPENTARIA. BY TAU 48 TC GRANT SHOULD EMERGE OVER THE GULF AND BEGIN TO RE-INTENSIFY TO 45 KNOTS BY TAU 72 WHERE IT WILL ONCE AGAIN MAKE LANDFALL OVER THE CAPE YORK PENINSULA. AFTER A BRIEF WEAKENING DUE TO FRICTIONAL FORCES THE SYSTEM SHOULD TRACK OUT OVER THE CORAL SEA AND BEGIN TO RE-INTENSIFY. FROM TAU 24 ONWARDS A NEAR EQUATORIAL RIDGE SHOULD BUILD NORTH OF THE LLCC AND PROVIDE A WESTWARD STEERING INFLUENCE FOR THE REMAINDER OF THE FORECAST. THE AVAILABLE NUMERICAL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THE EXCEPTION OF GFDN THAT TAKES THE VORTEX ON A SOUTHWEST TRACK. THIS FORECAST IS WITH THE REMAINDER OF THE TRACK ENVELOPE BUT JUST TO THE LEFT OF CONSENSUS TO OFFSET GFDN. ADDITIONALLY, DURING THE EXTENDED FORECAST FROM TAUS 96-120, THE OFFICIAL FORECAST IS SLOWER THAN CONSENSUS TO OFFSET THE VERY FAST TRACK SPEEDS OF THE GFS. NEXT WARNINGS AT 261500Z AND 270300Z.// ========================================================================= WTXS31 PGTW 20111226 15:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 03S (GRANT) WARNING NR 004// RMKS/ 1. TROPICAL CYCLONE 03S (GRANT) 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: 261200Z --- NEAR 14.3S 133.0E MOVEMENT PAST SIX HOURS - 155 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 14.3S 133.0E --- FORECASTS: 12 HRS, VALID AT: 270000Z --- 14.8S 133.5E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 100 DEG/ 05 KTS --- 24 HRS, VALID AT: 271200Z --- 15.0S 134.6E MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 090 DEG/ 10 KTS --- 36 HRS, VALID AT: 280000Z --- 15.0S 136.6E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 095 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 281200Z --- 15.1S 138.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 095 DEG/ 09 KTS --- 72 HRS, VALID AT: 291200Z --- 15.4S 142.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 96 HR POSIT: 090 DEG/ 05 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 301200Z --- 15.4S 144.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 095 DEG/ 07 KTS --- 120 HRS, VALID AT: 311200Z --- 15.7S 147.5E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 261500Z POSITION NEAR 14.4S 133.1E. TROPICAL CYCLONE (TC) 03S (GRANT), LOCATED APPROXIMATELY 755 NM WEST OF CAIRNS, AUSTRALIA, HAS TRACKED SOUTH-SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS LOST SOME CONVECTION ALTHOUGH THE LOW LEVEL CIRCULATION REMAINED INTACT AS IT CONTINUED TO TRACK OVER LAND. THE INITIAL POSITION WAS BASED ON A REFLECTIVITY RADAR LOOP FROM DARWIN. THE INITIAL INTENSITY WAS EXTRAPOLATED FROM NEARBY SURFACE OBSERVATIONS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS DIRECTLY UNDER THE RIDGE AXIS IN AN AREA OF LOW (05-10 KNOT) VERTICAL WIND SHEAR. IT IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A NEAR- EQUATORIAL RIDGE TO THE NORTHEAST. THE CYCLONE IS EXPECTED TO BEGIN TRACKING MORE EASTWARD AS THE STEERING RIDGE BUILDS AND EXTENDS FURTHER WESTWARD. IT IS EXPECTED TO REINTENSIFY AS IT EMERGES IN THE GULF OF CARPENTARIA AFTER TAU 24. THE AVAILABLE NUMERICAL GUIDANCE IS IN FAIR AGREEMENT WITH THIS TRACK FORECAST WHICH IS IN THE MIDDLE OF THE ENVELOPE AND ALONGSIDE JTWC CONSENSUS. NEXT WARNINGS AT 270300Z AND 271500Z.// ========================================================================= WTXS31 PGTW 20111227 03:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 03S (GRANT) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 03S (GRANT) 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: 270000Z --- NEAR 14.1S 132.9E MOVEMENT PAST SIX HOURS - 135 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, RADAR AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND REPEAT POSIT: 14.1S 132.9E --- FORECASTS: 12 HRS, VALID AT: 271200Z --- 14.2S 133.2E MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 270300Z POSITION NEAR 14.1S 133.0E. TROPICAL CYCLONE (TC) 03S (GRANT), LOCATED APPROXIMATELY 155 NM SOUTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES THAT THE SYSTEM HAS TRACKED WELL INLAND. CONVECTION ASSOCIATED WITH THIS SYSTEM HAS BECOME SHALLOW AND DISORGANIZED OVER THE PAST 12 HOURS. THE INITIAL POSITION IS BASED ON THE INFRARED SATELLITE ANIMATION AND A 270012Z 89H AMSU-B METOPA MICROWAVE SATELLITE IMAGE SHOWING A SINGLE FRAGMENTED BAND ON THE SOUTHERN PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER. THIS POSITION WAS ALSO SUPPORTED BY A 512 KM COMPOSITE RADAR REFLECTIVITY LOOP CENTERED ON KATHERINE, AUSTRALIA. THE INITIAL INTENSITY IS ESTIMATED FROM NEARBY SURFACE OBSERVATIONS. UPPER LEVEL ANALYSIS INDICATES TC 03S IS UNDERNEATH A RIDGE AXIS IN AN AREA OF LIGHT TO MODERATE (10 TO 20 KNOT) VERTICAL WIND SHEAR (VWS). THE SYSTEM IS EXPECTED TO CONTINUE WEAKENING AS IT DRIFTS OVER LAND DURING THE NEXT 48 HOURS. A NEAR-EQUATORIAL STEERING RIDGE TO THE NORTHEAST IS EXPECTED TO EXTEND WESTWARD AND STEER THE REMNANTS OF THE CYCLONE EASTWARD TOWARD THE GULF OF CARPENTARIA, WHERE REDEVELOPMENT IS POSSIBLE IN A FEW DAYS. THIS FORECAST FOLLOWS THE NUMERICAL MODEL CONSENSUS. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WARNING CENTER. THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.// ========================================================================= WTXS21 PGTW 201227 21:30z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE FORMATION ALERT// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 110 NM EITHER SIDE OF A LINE FROM 14.4S 135.4E TO 15.1S 140.7E 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 20 TO 25 KNOTS. METSAT IMAGERY AT 272100Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 14.5S 135.7E. THE SYSTEM IS MOVING EASTWARD AT 06 KNOTS. 2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.2S 134.2E IS NOW LOCATED NEAR 14.5S 135.8E, APPROXIMATELY 595 NM WEST- NORTHWEST OF CAIRNS, AUSTRALIA. RECENT ANIMATED INFRARED SATELLITE IMAGERY INDICATES THAT ALTHOUGH THE OVERALL CIRCULATION IS BROAD, CONVECTION IS BEGINNING TO CONSOLIDATE AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). THE SYSTEM HAS MOVED INTO THE WARM WATERS OF THE GULF OF CARPENTARIA AND IS RE-INTENSIFYING. RECENT SURFACE OBSERVATIONS FROM GOVE INDICATE A 2 MB PRESSURE FALL OVER THE PAST 24 HOURS. A 271244Z AMSU-B METOPA MICROWAVE IMAGE SHOWS SOME CURVED, FRAGMENTED BANDING WRAPPING INTO THE LLCC. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS SOUTH OF THE RIDGE AXIS, IN A DIFFLUENT REGION WITH 20 TO 25 KNOTS OF VERTICAL WIND SHEAR. THE SYSTEM HAS AN EXCELLENT POLEWARD OUTFLOW CHANNEL, AND EQUATORWARD OUTFLOW WILL IMPROVE AS A THE NEAR-EQUATORIAL RIDGE EXTENDING OVER NORTHEASTERN AUSTRALIA MOVES WESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 282130Z.// ========================================================================= WTXS21 PGTW 20111228 21:30z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE FORMATION ALERT CANCELLATION// REF/A/MSG/NAVMARFCSTCEN PEARL HARBOR HI/272121Z DEC 11// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. REMARKS: THIS CANCELS REF A (WTXS21 PGTW 272130). THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.1S 135.5E IS NOW LOCATED NEAR 14.3S 137.9E, APPROXIMATELY 485 NM WEST-NORTHWEST OF CAIRNS, AUSTRALIA. RECENT ANIMATED WATER VAPOR SATELLITE IMAGERY SHOWS DEEP CONVECTION CONFINED TO A BAND ALONG THE FAR EASTERN PERIPHERY OF AN ELONGATED LOW LEVEL CIRCULATION CENTER (LLCC) EVIDENT IN A 281958Z SSMIS IMAGE. THE DISTURBANCE LIES IN AN AREA OF MODERATE VERTICAL WIND SHEAR AND SUBSIDENCE ALOFT ASSOCIATED WITH AN UPPER LEVEL TROUGH ENCROACHING ON THE CYCLONE FROM THE SOUTHWEST. THOUGH VERY WARM WATER IN THE GULF OF CARPENTARIA MAY SUPPORT FURTHER DEVELOPMENT, THE DISTURBANCE IS NO LONGER EXPECTED TO CONSOLIDATE INTO A TROPICAL CYCLONE THAT REACHES THE WARNING INTENSITY THRESHOLD OF 35 KNOTS WITHIN THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 22 TO 27 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 MB. DUE TO THE UNFAVORABLE UPPER-LEVEL CONDITIONS AND ELONGATED LLCC, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO MEDIUM.//
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Document: tropical_cyclone_grant.htm | Updated: 8 January 2012 |