WTPN21 PHNC 181830
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90E)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 12.7N 98.1W TO 15.4N 100.9W
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 23 TO 28 KNOTS. METSAT
IMAGERY AT 181200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 13.1N 98.3W. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 11
KNOTS.
2. REMARKS: AN AREA OF CONVECTION HAS PERSISTED NEAR 13.1N 98.3W, 
APPROXIMATELY 1568 NM SOUTHEAST OF SAN DIEGO, CA. ANIMATED MULTISPECTRAL 
SATELLITE IMAGERY SHOWS DEEP CONVECTION WITH SHALLOW RAIN BANDS WRAPPING 
INTO A PARTIALLY EXPOSED LOW LEVEL CIRCULATION. AN 181628Z ASCAT B PASS 
REVEALS A SMALL PATCH OF 25-30 KT WINDS IN THE EASTERN QUADRANT OF THE 
AREA. ENVIRONMENTAL ANALYSIS DEMONSTRATES THAT THE INVEST IS IN A 
FAVORABLE ENVIRONMENT FOR DEVELOPMENT. THERE IS ROBUST POLEWARD OUTFLOW 
ALOFT, WARM (29-30C) SEA SURFACE TEMPERATURES AND LOW (10-15KTS) VERTICAL 
WIND SHEAR. MODEL GUIDANCE IS IN GENERAL AGREEMENT THAT 90E WILL TRACK 
NORTHWEST OVER THE NEXT 24 HOURS THEN NORTH TOWARDS MEXICO. MAXIMUM 
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 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 
191830Z.
//
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