WTPN21 PGTW 250600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 9.6N 138.3E TO 13.4N 131.4E 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 20 TO 25 KNOTS. METSAT IMAGERY AT 250530Z
INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 10.0N 138.0E.
THE SYSTEM IS MOVING NORTHWESTWARD AT 11 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED
NEAR 7.9N 139.5E, IS NOW LOCATED NEAR 10.0N 138.0E, APPROXIMATELY 30
NM NORTH-NORTHWEST OF YAP. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND A 242353Z MHS 89GHZ MICROWAVE IMAGE DEPICT A BROAD LOW LEVEL
CIRCULATION WITH FLARING CONVECTION OVER THE WESTERN SEMICIRCLE. A
250035Z PARTIAL ASCAT-C IMAGE SHOWS 20-25 KNOT WINDS OVER THE
EASTERN SEMICIRCLE. UPPER LEVEL ANALYSIS REVEALS A MARGINALLY
FAVORABLE ENVIRONMENT WITH MODERATE TO HIGH (20-25 KNOTS) VERTICAL
WIND SHEAR OFFSET BY STRONG DIFFLUENCE ALOFT. GLOBAL MODELS ARE IN
GOOD AGREEMENT SHOWING 99W TRACKING WEST-NORTHWESTWARD TOWARD LUZON
WITH SLOW CONSOLIDATION OVER THE NEXT TWO DAYS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1004 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
260600Z.//
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