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Tropical Cyclone GRANT : JTWC Advisories
Season 2011-2012 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone GRANT Track Map and Data

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.//

Tropical cyclone tracks developed by Michael Bath using operational warnings and advisories.


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Document: tropical_cyclone_grant_jtwc_advisories.htm Updated: 2 May 2017