WTPS21 PHNC 050230
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
130 NM EITHER SIDE OF A LINE FROM 17.8S 176.0W TO 22.4S 175.0W
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 25 TO 30 KNOTS. METSAT IMAGERY AT
050200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 18.4S
176.0W. THE SYSTEM IS MOVING SOUTHWARD AT 09 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 17.6S
175.3W, IS NOW LOCATED NEAR 18.4S 176.0W, APPROXIMATELY 390 NM
SOUTHWEST OF PAGO PAGO, AMERICAN SAMOA. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS A PERSISTENT AREA OF DEEP CONVECTION
OBSCURING A PARTIALLY-EXPOSED, LOW-LEVEL CIRCULATION CENTER (LLCC).
A 042135Z METOP-B 89 GHZ MICROWAVE IMAGE REVEALS A SLOWLY-
CONSOLIDATING SYSTEM WITH CURVED BANDING WRAPPING INTO THE LLCC. A
042040Z ASCAT IMAGE DEPICTS A WELL-DEFINED CIRCULATION WITH 25 TO 30
KNOT WINDS OVER THE NORTHERN SEMI-CIRCLE AND 15 TO 20 KNOT WINDS
OVER THE SOUTHERN SEMICIRCLE. UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (10 TO 15
KNOTS) VERTICAL WIND SHEAR AND FAIR OUTFLOW. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1000 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
060230Z.//