WTPN21 PHNC 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/222051Z JUL 12//
AMPN/REF IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 10.3N 112.4W TO 12.1N 120.1W
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 18 TO 23 KNOTS. METSAT IMAGERY AT
231800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 10.4N
113.0W. THE SYSTEM IS MOVING WESTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.0N
110.2W IS NOW LOCATED NEAR 10.4N 113.0W, APPROXIMATELY 760 NM
SOUTHWEST OF PUERTO VALLARTA, MEXICO. RECENT ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS AN AREA OF PERSISTENT DEEP CONVECTION OVER
THE NORTHERN PERIPHERY OF AN ELONGATED LOW LEVEL CIRCULATION CENTER
(LLCC). A 231636Z 89H METOP-A MICROWAVE IMAGE SHOWS A CONSOLIDATING
LLCC WITH A CURVED BAND OF DEEP CONVECTION ALONG THE NORTHERN
PERIPHERY OF THE SYSTEM. A 231636Z PARTIAL ASCAT IMAGE INDICATES 20
TO 25 KNOT WINDS CONVERGING INTO THE SYSTEM ALONG THE EASTERN
QUADRANTS. UPPER-LEVEL ANALYSIS INDICATES THAT THE SYSTEM LIES JUST
TO THE SOUTH OF THE RIDGE AXIS, IN AN AREA OF MODERATE DIVERGENCE
WITH AN UPPER LEVEL TROUGH TO THE NORTHWEST ENHANCING POLEWARD
OUTFLOW. UPPER LEVEL ANALYSIS ALSO SHOWS WEAK VERTICAL WIND SHEAR
(10 TO 15 KNOTS). SEA SURFACE TEMPERATURES IN THE REGION ARE
ESTIMATED AT 26-29 DEGREES CELSIUS AND WILL REMAIN FAVORABLE FOR
DEVELOPMENT AS THE SYSTEM CONTINUES TO TRACK WEST-NORTHWESTWARD OVER
THE NEXT 12 TO 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1005 MB. DUE TO SLOWLY IMPROVING ORGANIZATION AND
FAVORABLE UPPER-LEVEL CONDITIONS, THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH. THIS
SUPERSEDES REF A (WTPN21 PHNC 222100).
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
242100Z.//
