ABPW10 PGTW 250600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS/250600Z-260600ZOCT2021//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/250151ZOCT2021//
REF/B/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/250521ZOCT2021//
NARR/REF A IS A TROPICAL CYCLONE WARNING. REF B IS A TROPICAL
/CYCLONE FORMATION ALERT.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY:
      (1) AT 25OCT21 0000Z, TROPICAL STORM 25W (MALOU) WAS LOCATED 
NEAR 16.1N 138.4E, APPROXIMATELY 379 NM NORTH OF ULITHI, AND HAD 
TRACKED NORTH-NORTHWESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. 
MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 35 KNOTS GUSTING 
TO 45 KNOTS. SEE REF A (WTPN31 PGTW 250300) FOR FURTHER DETAILS.
      (2) NO OTHER TROPICAL CYCLONES.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED 
NEAR 10.5N 117.8E IS NOW LOCATED NEAR 11.2N 113.7E, APPROXIMATELY 
311 NM WEST-NORTHWEST OF PUERTO PRINCESA, PHILIPPINES. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CURVED DEEP CONVECTIVE 
BANDING THAT APPEARS TO BE WRAPPING INTO A PARTIALLY-EXPOSED LLC. 
THIS BANDING CAN ALSO BE SEEN IN A 242334Z 91GHZ SSMIS IMAGE, BUT A 
250008Z ASCAT-A IMAGE INDICATES THAT THE BROAD AREA OF 20-25 KT 
WINDS UNDER THE BANDING IS PART OF THE COLD SURGE EVENT TO THE NORTH 
AND NOT ASSOCIATED WITH THE BROAD CIRCULATION. ENVIRONMENTAL 
ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT, WITH 
MODERATE EQUATORWARD OUTFLOW, LOW (10-15 KTS) VERTICAL WIND SHEAR 
(VWS) AND WARM (29-30 C) SEA SURFACE TEMPERATURES (SST). GLOBAL 
NUMERICAL MODELS ARE IN GOOD AGREEMENT THAT INVEST 99W WILL TRACK 
WEST-NORTHWESTWARD AND MAKE LANDFALL OVER VIETNAM WITHIN THE NEXT 36 
HOURS. THE MODELS INDICATE THE POSSIBILITY OF A WEAK TROPICAL 
DEPRESSION BEFORE LANDFALL, BUT THE CURRENT TRACK SPEED OF INVEST 
99W, WHICH IS FASTER THAN IN MODEL GUIDANCE, INDICATES THE SYSTEM 
MAY MAKE LANDFALL SOONER WITH LESS TIME OVER WATER TO REACH WARNING 
CRITERIA. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1009 MB. 
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE 
WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH. SEE REF B (WTPN21 PGTW 
250530) FOR FURTHER DETAILS.
      (2) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
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