Tropical Cyclone Formation Alert WTPN21 Issued at 14/1000Z
WTPN21 PGTW 141000
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
170 NM EITHER SIDE OF A LINE FROM 6.2N 149.4E TO 6.4N 136.1E
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 15 TO 20 KNOTS. METSAT
IMAGERY AT 140900Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 6.4N 148.5E. THE SYSTEM IS MOVING WESTWARD AT 12 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 95W) PREVIOUSLY LOCATED
NEAR 6.0N 151.2E, IS NOW LOCATED NEAR 6.4N 148.5E, APPROXIMATELY 475
NM SOUTH-SOUTHEAST OF NAVAL BASE GUAM. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY AND A 140759Z WINDSAT 37GHZ MICROWAVE IMAGE DEPICT
A SLIGHTLY ELONGATED LLCC BELOW PERSISTENT CONVECTION WITH
FRAGMENTARY, FORMATIVE BANDING WRAPPING IN FROM THE NORTH. 95W IS
CURRENTLY UNDER LOW TO MODERATE (15-20KT) VERTICAL WIND SHEAR AND
STRONG DIVERGENCE DUE TO STRONG SOUTHEASTERLY UPPER LEVEL FLOW. SSTS
ARE FAVORABLE (28-30C) FOR FURTHER TROPICAL DEVELOPMENT. GLOBAL
MODELS ARE IN STRONG AGREEMENT THAT THE SYSTEM WILL TRACK TO THE
WEST BUT VARY ON TIMING AND INTENSITY. THERE IS SOME UNCERTAINTY IN
THIS ASSESSMENT DUE TO MODEL SPATIAL RESOLUTION AND THE SMALL SIZE
OF THE DISTURBANCE. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT
15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR
1007 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
151000Z.//
NNNN
(1) AN AREA OF CONVECTION (INVEST 95W) HAS PERSISTED NEAR 5.4N
155.3E, APPROXIMATELY 234 NM EAST-SOUTHEAST OF CHUUK ISLAND.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 130239Z AMSR2 89GHZ
PARTIAL MICROWAVE IMAGE DEPICT A CONSOLIDATING LLC BELOW A BROAD
REGION OF FLARING CONVECTION WITH FRAGMENTARY, FORMATIVE BANDING
WRAPPING IN FROM THE NORTHEAST. A 122233Z DIRECT ASCAT PASS SHOWS A
DEFINED AND TIGHT CIRCULATION WITH A FEW 20KT WIND BARBS IN THE CORE
AND ISOLATED 25KT WINDS TO THE NORTH AND WEST UNDER THE FRAGMENTED
BANDING. 95W IS CURRENTLY UNDER MODERATE (15-25KT) VERTICAL WIND
SHEAR WITH STRONG ASSOCIATED DIVERGENCE DUE TO ROBUST SOUTHEASTERLY
UPPER LEVEL FLOW. SSTS ARE FAVORABLE (28-30C) FOR FURTHER TROPICAL
DEVELOPMENT. GLOBAL MODELS ARE IN STRONG AGREEMENT ON A STRAIGHT
WESTWARD TRACK BUT VARY ON INTENSITY, WITH GFS AND NAVGEM PREDICTING
POSSIBLE FORMATION AS A WEAK TROPICAL STORM AND THE ECMWF AND UKMO
BELOW TROPICAL DEPRESSION STRENGTH. THERE IS SOME UNCERTAINTY IN THIS
ASSESSMENT DUE TO MODEL SPATIAL RESOLUTION AND THE SMALL SIZE OF THE
DISTURBANCE. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO
20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1010 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS MEDIUM.
