WTPN21 PGTW 251700
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 3.0N 158.2E TO 4.5N 155.0E 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 251630Z
INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 3.1N 157.8E. THE
SYSTEM IS MOVING WESTWARD AT 05 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 2.6N
158.5E IS NOW LOCATED NEAR 3.1N 157.8E, APPROXIMATELY 220 NM SOUTH
OF POHNPEI. ANIMATED INFRARED SATELLITE IMAGERY INDICATES A
CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED
CONVECTIVE BANDING. A 251424Z AMSU IMAGE DEPICTS DEEP CONVECTIVE
BANDING OVER THE SOUTHERN SEMI-CIRCLE WRAPPING INTO THE SOUTHEAST
QUADRANT OF AN ELONGATED LLCC. A 251058Z PARTIAL ASCAT IMAGE SHOWS
15 TO 20 KNOT WINDS OVER THE EASTERN SEMI-CIRCLE, INDICATIVE OF THE
RECENT CONSOLIDATION OF THE LLCC. UPPER-LEVEL ANALYSIS INDICATES
THAT THE LLCC IS LOCATED UNDER A DEVELOPING ANTICYCLONE, WHICH IS
PROVIDING AMPLE RADIAL OUTFLOW. OVER THE PAST 12 HOURS, VERTICAL
WIND SHEAR HAS BECOME MORE FAVORABLE AND IS NOW WEAK (10 TO 15
KNOTS). 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
261700Z.//
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