Tropical Cyclones [Index]

Tropical Cyclone 201219 Southern Hemisphere Summary

WTXS21 PGTW 20120506 17:30z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
A 170 NM RADIUS OF 5.4S 127.1E WITHIN THE NEXT 12 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 25 TO 30 KNOTS. METSAT IMAGERY AT 061700Z INDICATES THAT A
CIRCULATION CENTER IS LOCATED NEAR 5.4S 127.1E. THE SYSTEM IS
MOVING EAST-SOUTHEASTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 4.5S
126.2E, IS NOW LOCATED NEAR 5.4S 127.1E, APPROXIMATELY 470 NM NORTH-
NORTHWEST OF DARWIN, AUSTRALIA. ANIMATED MULTISPECTRAL AND INFRARED
SATELLITE IMAGERY OVER THE PAST 18 HOURS HAS SHOWN THE LOW-LEVEL
CIRCULATION CENTER (LLCC) TRANSITION FROM BEING FULLY-EXPOSED INTO
MORE RECENT CENTRAL CLOUD COVER FROM BANDING OVER THE EASTERN SEMI-
CIRCLE OF THE LLCC. A 061239Z ASCAT PASS INDICATES 30 KNOT WINDS
OVER THE NORTH-NORTHWESTERN QUADRANT, APPROXIMATELY 25 NM FROM THE
LLCC. ADDITIONALLY, STRONG (30-40 KNOT) SOUTHERLY WINDS FROM SEVERAL
DEGREES SOUTH OF THE LLCC CAN BE SEEN FEEDING INTO THE CIRCULATION.
UPPER-LEVEL ANALYSIS INDICATES THE LLCC TO BE APPROXIMATELY 13
DEGREES WEST OF A POINT SOURCE OF DIFFLUENCE AND 7 DEGREES
EQUATORWARD OF THE SUBTROPICAL RIDGE AXIS. IT SEEMS THAT THE LLCC
HAS INCREASED ITS DISTANCE FROM THE EASTERLY VERTICAL WIND SHEAR
(VWS), WHICH HAS BEEN PROVIDED BY THE POINT SOURCE OF DIFFLUENCE
LOCATED TO THE EAST, OVER THE PAST 12 HOURS. THUS, VWS HAS SLIGHTLY
RELAXED ALLOWING FOR THE BANDING TO REFORM OVER THE LLCC. ANIMATED
WATER VAPOR IMAGERY SHOWS GOOD EQUATORWARD OUTFLOW BUT POLEWARD
OUTFLOW REMAINS SUBDUED AND MOSTLY STRAIGHT-LINE TO THE WEST. EARLY
MODEL GUIDANCE SUGGESTS A GENERALLY POLEWARD TRACK IN A
SOUTHWESTWARDS DIRECTION. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 25-30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO
BE NEAR 1000 MB. DUE TO THE RECENT DECREASE IN VWS, GENERAL TRACK
MOTION INTO CONTINUED WEAK VWS, AND CONSOLIDATION OF BANDING, 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
071730Z.//
=========================================================================
WTXS31 PGTW 20120507 09:00z AMD
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 19S (NINETEEN) WARNING NR 001A AMENDED//
RMKS/
1. TROPICAL CYCLONE 19S (NINETEEN) WARNING NR 001A AMENDED
   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 6.9S 129.3E
     MOVEMENT PAST SIX HOURS - 115 DEGREES AT 11 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: 6.9S 129.3E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   071800Z --- 7.6S 129.3E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   VECTOR TO 24 HR POSIT: 215 DEG/ 05 KTS
    ---
   24 HRS, VALID AT:
   080600Z --- 8.4S 128.7E
   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
                            040 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 215 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   081800Z --- 9.7S 127.7E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 220 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   090600Z --- 10.8S 126.7E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 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
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 230 DEG/ 06 KTS
    ---
   72 HRS, VALID AT:
   100600Z --- 12.3S 124.9E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 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
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 260 DEG/ 05 KTS
    ---
   LONG RANGE OUTLOOK:
    ---
   96 HRS, VALID AT:
   110600Z --- 12.7S 122.7E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   VECTOR TO 120 HR POSIT: 260 DEG/ 06 KTS
    ---
   120 HRS, VALID AT:
   120600Z --- 13.0S 120.4E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
REMARKS:
070900Z POSITION NEAR 7.1S 129.3E.
TROPICAL CYCLONE (TC) 19S, LOCATED APPROXIMATELY 345 NM NORTH-
NORTHWEST OF DARWIN, AUSTRALIA, HAS TRACKED EAST-SOUTHEASTWARD AT
11 KNOTS DURING THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS A BROAD, EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC) WITH DEEP CONVECTION SHEARED TO THE WEST-SOUTHWEST. THE
INITIAL POSITION WAS BASED ON THE MSI. THE INITIAL INTENSITY WAS
BASED ON PGTW AND KNES DVORAK ESTIMATES RANGING FROM 30 TO 45 KNOTS.
A 070120Z ASCAT PASS DEPICTS AN ELONGATED LLCC WITH 30 KNOT WINDS
WRAPPING AROUND THE OUTER PERIPHERY. UPPER LEVEL ANALYSIS INDICATES
THE SYSTEM IS LOCATED NORTH OF THE SUBTROPICAL RIDGE AXIS IN AN AREA
OF MODERATE VERTICAL WIND SHEAR AND MODERATE DIVERGENCE ALOFT. TC
19S IS EXPECTED TO INITIALLY TURN POLEWARD AS A SUBTROPICAL STEERING
RIDGE CENTERED OVER THE TOP END OF AUSTRALIA STRENGTHENS. THE SYSTEM
SHOULD TRACK GENERALLY SOUTHWESTWARD THROUGHOUT THE FORECAST PERIOD
UNDER THIS STEERING INFLUENCE. TC 19S IS EXPECTED TO GRADUALLY
INTENSIFY AS IT TRACKS INTO A MORE FAVORABLE UPPER LEVEL
ENVIRONMENT, CLOSER TO THE UPPER LEVEL RIDGE AXIS. HOWEVER, AFTER
TAU 72, VERTICAL WIND SHEAR SHOULD INCREASE AND CAUSE THE SYSTEM TO
WEAKEN. NUMERICAL MODEL GUIDANCE IS INITIALLY IN GOOD AGREEMENT
UNTIL AFTER TAU 36, WHEN THE MODELS DIVERGE. BOTH GFDN AND GFS
MAINTAIN A MORE POLEWARD TRACK, WHERE UKMO AND NOGAPS MAINTAIN A
MORE WESTWARD TRACK WITH A STRONGER STEERING RIDGE. THIS FORECAST
FAVORS A MORE POLEWARD TRACK AND IS SLIGHTLY SOUTH OF MODEL
CONSENSUS AT THE END OF THE FORECAST. JUSTIFICATION FOR AMENDMENT:
NEW MSI SHOWED THE LLCC TRACKED FARTHER SOUTHEASTWARD BEFORE THE
TURN POLEWARD THAN PREVIOUSLY EXPECTED. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 070600Z IS 10 FEET.//
=========================================================================
WTXS31 PGTW 20120507 15:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 19S (NINETEEN) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 19S (NINETEEN) 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:
   071200Z --- NEAR 8.1S 129.8E
     MOVEMENT PAST SIX HOURS - 160 DEGREES AT 13 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   REPEAT POSIT: 8.1S 129.8E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   080000Z --- 8.9S 129.7E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   VECTOR TO 24 HR POSIT: 210 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   081200Z --- 10.0S 129.0E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
REMARKS:
071500Z POSITION NEAR 8.3S 129.8E.
TROPICAL CYCLONE (TC) 19S, LOCATED APPROXIMATELY 270 NM NORTH-
NORTHWEST OF DARWIN, AUSTRALIA, HAS TRACKED SOUTH-SOUTHEASTWARD AT
13 KNOTS DURING THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE
IMAGERY SHOWS TC 19S HAS WEAKENED SIGNIFICANTLY IN THE PAST 12 HOURS
AND NOW HAS MINIMAL ASSOCIATED DEEP CONVECTION. ADDITIONALLY, A
071110Z SSMIS DEPICTS A VERY WEAK, FULLY EXPOSED LOW LEVEL
CIRCULATION CENTER, FROM WHICH THE INITIAL POSITION WAS BASED. THE
INITIAL INTENSITY WAS ON THE LOWER SIDE OF THE KNES AND PGTW 25 TO
35 KNOT DVORAK ESTIMATES BECAUSE OF THE WEAK CONVECTIVE SIGNATURE IN
MICROWAVE IMAGERY. TC 19S IS EXPECTED TO CONTINUE TO WEAKEN UNDER
HIGH VERTICAL WIND SHEAR, BUT COULD POTENTIALLY REDEVELOP AS IT
TRACKS UNDER THE SUBTROPICAL RIDGE AXIS TO THE SOUTH. THIS IS THE
FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WARNING CENTER.
THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 071200Z IS 10 FEET.//
=========================================================================
WTXS21 PGTW 20120508 20:30z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
110 NM EITHER SIDE OF A LINE FROM 8.6S 129.6E TO 11.6S 126.0E WITHIN
THE NEXT 12 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 32 KNOTS. METSAT IMAGERY AT 081732Z
INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 9.4S 128.9E. THE
SYSTEM IS MOVING SOUTHWESTWARD AT 05 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (REMNANTS OF TC 19S) PREVIOUSLY
LOCATED NEAR 9.0S 129.2E IS NOW LOCATED NEAR 9.4S 128.9E,
APPROXIMATELY 215 NM NORTH-NORTHWEST OF DARWIN, AUSTRALIA. ANIMATED
INFRARED SATELLITE IMAGERY REVEALS BANDING CONVECTION PERSISTING
OVER THE PAST 12 HOURS, WITH A DEVELOPING LOW LEVEL CIRCULATION
CENTER (LLCC). A 081540Z OSCAT PASS INDICATED WINDS BETWEEN 20 TO 25
KNOTS ALONG THE SOUTHERN PERIPHERY WITH STRONGER WINDS (30 KNOTS)
FURTHER TO THE SOUTH. UPPER LEVEL ANALYSIS INDICATES THE LLCC
REMAINS EQUATORWARD OF A SUBTROPICAL RIDGE AXIS WITH LOW TO MODERATE
LEVELS OF VERTICAL WIND SHEAR (VWS) (10 TO 15 KNOTS) ENHANCING
POLEWARD VENTILATION. AS THE LLCC APPROACHES THE RIDGE AXIS,
DECREASING VWS AND INCREASING VENTILATION WILL LIKELY CAUSE THE
REMNANTS OF TC 19S TO REGENERATE WITHIN THE NEXT 24 HOURS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 32 KNOTS, BASED ON AN
IMPROVING CONVECTIVE SIGNATURE IN THE ANIMATED INFRARED IMAGERY.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. BASED ON
THE DEEP BANDING CONVECTION PERSISTING, GOOD POLEWARD OUTFLOW AND
FAVORABLE SURFACE CONDITIONS, 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
092030Z.//
=========================================================================
WTXS21 PGTW 20120509 14:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT CANCELLATION//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/082021Z MAY 12//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 082030)//
RMKS/
1. REMARKS: THIS CANCELS REF A. THE AREA OF CONVECTION (REMNANTS OF
TC 19S) PREVIOUSLY LOCATED NEAR 9.4S 128.9E IS NOW LOCATED NEAR
10.0S 126.9E, APPROXIMATELY 270 NM WEST-NORTHWEST OF DARWIN,
AUSTRALIA. RECENT ANIMATED ENHANCED INFRARED IMAGERY (EIR) SHOWS A
SUBSTANTIAL DEGRADATION OF THE LOW LEVEL CIRCULATION CENTER (LLCC)
AND ASSOCIATED CONVECTION OVER THE PAST 12 HOURS. THE SYSTEM HAS
STRUGGLED TO ORGANIZE, LIKELY DO TO SURFACE INTERACTION WITH ISLANDS
IN THE AREA. ADDITIONALLY, AN ANIMATED TOTAL PRECIPITABLE WATER LOOP
SHOWS THAT A RIBBON OF DRIER AIR HAS WRAPPED AROUND THE NORTHERN AND
EASTERN PERIPHERIES OF THE LLCC, WHICH IS CONSISTENT WITH THE EIR.
THE LATEST WIND SPEED ESTIMATES FROM PGTW AND KNES ARE 25 KNOTS OR
LESS. RECENT SCATTEROMETRY PASSES HAVE ONLY HAD PARTIAL COVERAGE,
HOWEVER THIS LIMITED DATA SUPPORTS THE DVORAK ESTIMATES ABOVE.
DESPITE THE POOR ORGANIZATION, THIS SYSTEM MAINTAINS A STRONG
VORTICITY SIGNATURE, MODERATE VERTICAL WIND SHEAR (VWS) OF 15-20
KTS, FAVORABLE SST (28 DEGREES C), AND FAIR UPPER-LEVEL DIVERGENCE.
NUMERICAL MODEL GUIDANCE CONTINUES TO SUGGEST REGENERATION IS
POSSIBLE. DUE TO THE LACK OF ORGANIZATION AND THE LOSS OF CENTRAL
DEEP CONVECTION, THE POTENTIAL FOR DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO MEDIUM.//