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WTPN21 PHNC 061900

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//

SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99E)//

RMKS/

1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN

100 NM EITHER SIDE OF A LINE FROM 16.7N 103.4W TO 19.3N 107.1W

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 061800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED

NEAR 16.9N 103.7W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 06

KNOTS.

2. REMARKS: AN AREA OF CONVECTION (INVEST 99E) IS LOCATED NEAR 16.9N

103.7W, APPROXIMATELY 130NM SOUTH-SOUTHEAST OF MANZANILLO, MEXICO.

ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP CONVECTION

BUILDING NEAR THE LOW LEVEL CIRCULATION CENTER (LLCC). A 061630Z

ASCAT-B SCATTEROMETERY PASS REVEALS ISOLATED BANDS OF 20-25 KNOT WINDS

WRAPPING INTO THE LLCC. ENVIRONMENTAL ANALYSIS INDICATES THAT 99E IS

IN AN OVERALL FAVORABLE AREA FOR DEVELOPMENT WITH WARM (28-29C) SEA

SURFACE TEMPERATURES, GOOD OUTFLOW ALOFT, AND LOW TO MODERATE (15-20

KNOTS) VERTICAL WIND SHEAR. NUMERICAL MODELS ARE IN AGREEMENT THAT 99E

WILL CONTINUE TO TRACK NORTH-NORTHWESTWARD AND INTENSIFY OVER THE NEXT

24-36 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28

KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 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

071900Z.//

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