WTPN21 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 4.9N 143.2E TO 7.4N 137.6E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 210000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 4.9N 142.7E. THE SYSTEM IS MOVING WESTWARD AT 11 KNOTS.
2. REMARKS: AN AREA OF CONVECTION (INVEST 98W), PREVIOUSLY LOCATED 
NEAR 4.8N 148.7E IS NOW LOCATED NEAR 4.9N 142.7E, APPROXIMATELY 384 
NM SOUTHEAST OF YAP, FSM. ANIMATED MULTISPECTRAL IMAGERY DEPICTS 
CONVECTIVE BANDING WRAPPING INTO A LOW LEVEL CICULATION CENTER 
EVIDENT IN A 202314 METOP-A 89GHZ MICROWAVE IMAGE. A 210030Z METOP-B 
ASCAT PASS DEPICTS 25 KNOT WINDS WRAPPING AROUND THE NORTHERN AND 
WESTERN PERIPHERY OF THE SYSTEM WITH SOME 30 KNOT WINDS TO THE 
NORTH. HOWEVER, WINDS TO THE SOUTH AND EAST REMAIN WEAK (10 TO 15 
KNOTS), BUT ONLY A SLIGHT IMPROVEMENT IN THE STRUCTURE OF THE SYSTEM 
WILL ENABLE IT TO REACH WARNING CRITERIA. WARM (30-31C) SEA SURFACE 
TEMPERATURES AND POLEWARD OUTFLOW ALOFT ARE CONDUCIVE FOR SOME 
FURTHER DEVELOPMENT. HOWEVER, THESE FAVORABLE CONDITIONS ARE OFFSET 
BY MODERATE (15-25 KTS) VERTICAL WIND SHEAR, WHICH WILL BE A 
SIGNIFICANT LIMITING FACTOR IN THE NEAR TERM, SO ANY FURTHER 
DEVELOPMENT IS EXPECTED TO BE GRADUAL. GLOBAL MODELS SUGGEST A TRACK 
TOWARD THE WEST-NORTHWEST AS 98W SLOWLY INTENSIFIES. MAXIMUM 
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 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 
220300Z.
//
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