WTIO21 PGTW 081000
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90B)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 6.2N 84.7E TO 9.4N 81.7E 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 27 TO 32 KNOTS. METSAT IMAGERY AT
080600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 6.4N
84.5E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 12 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 90B) PREVIOUSLY LOCATED
NEAR 5.2N 86.5E IS NOW LOCATED NEAR 6.4N 84.5E, APPROXIMATELY 
279 NM EAST OF COLOMBO, SRI LANKA. RECENT ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY DEPICT A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER 
(LLCC) OBSCURED BY PERSISTENT CONVECTION. FURTHERMORE, A 080421Z METOP-C 
ASCAT PASS DEPICTS A PATCH OF 30KT WINDS ALONG THE WESTERN PERIPHERY AND 
25KT WINDS ALONG THE NORTHERN PERIPHERY OF THE SYSTEM. THE ENVIRONMENT 
IS FAVORABLE FOR DEVELOPMENT MOVING FORWARD, WITH A STRONG POLEWARD 
OUTFLOW CHANNEL AND WARM (28-29C) SEA SURFACE TEMPERATURES. THE MAIN 
HINDRANCE BEING THE MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR 
THAT COULD LIMIT INTENSIFICATION BY TILTING THE STRUCTURE OF THE SYSTEM 
AND DISRUPTING DEEP CONVECTION. BOTH DETERMINISTIC AND ENSEMBLE MODELS 
AGREE ON A NORTHWEST TRACK TOWARD SRI LANKA OVER THE NEXT 48 HOURS, WITH 
THE ECMWF ENSEMBLE ESPECIALLY, PREDICTING QUICKER AND MORE INTENSE 
DEVELOPMENT OF 90B. DETERMINISTIC MODELS REMAIN RELUCTANT TO INTENSIFY 
THE SYSTEM BEYOND 35 KNOTS. MAXIMUM SUSTAINED SURFACE WINDS ARE 
ESTIMATED AT 27 TO 32 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 HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
091000Z.//
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