ABPW10 PGTW 211300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS REISSUED/211300Z-220600ZSEP2021//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/211221SEP2021//
NARR/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED 
NEAR 10.3N 154.6E IS NOW LOCATED NEAR 11.2N 151.5E, APPROXIMATELY 
420 NM EAST-SOUTHEAST OF GUAM. A 211052Z METOP-B PASS SHOWS THAT A 
DISCREET LOW-LEVEL CIRCULATION CENTER (LLCC) HAS CONSOLIDATED OVER 
THE PAST 12 HOURS, WITH A SMALL BUT WELL-DEFINED CIRCULATION 
SURROUNDED BY 12-17 KNOT WINDS. A BAND OF 20-25 KNOT WINDS EXTENDS 
FROM SOUTH TO SOUTHEAST OF THE CENTER. ANIMATED ENHANCED INFRARED 
IMAGERY AND A 210811Z SSMIS 91GHZ IMAGE DEPICTS FLARING DISORGANIZED 
CONVECTION PRIMARILY ON THE SOUTH AND EAST SIDE OF THE ROTATION. 
ENVIRONMENTAL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT FOR 
DEVELOPMENT WITH A COMBINATION OF STRONG OUTFLOW ALOFT WITH A POINT 
SOURCE OR ANTICYCLONE ALOFT DIRECTION OVERHEAD THE LLCC, LOW (10 KT) 
VERTICAL WIND SHEAR (VWS) AND VERY WARM (30-31C) SEA SURFACE 
TEMPERATURES (SST). GLOBAL MODELS ARE GOOD IN AGREEMENT THAT INVEST 
99W WILL CONTINUE TRACKING NORTHWESTWARD OVER THE NEXT 24-48 HOURS 
HOWEVER, THEY ARE SPLIT ON THE DEGREE OF DEVELOPMENT. GFS, ITS 
ENSEMBLE, AND NAVGEM ARE THE MOST AGGRESSIVE, INDICATING FAIRLY 
RAPID CONSOLIDATION AND INTENSIFICATION, REACHING TROPICAL 
DEPRESSION STRENGTH WITHIN THE NEXT 24 HOURS AND TROPICAL STORM 
STRENGTH WITHIN THE NEXT 48 HOURS OR LESS, PRIOR TO PASSAGE THROUGH 
THE MARIANAS ISLAND CHAIN. ECMWF AND ITS ENSEMBLE ARE MUCH MORE 
RESERVED, INDICATING LITTLE TO NO DEVELOPMENT UNTIL AFTER TAU 
48, WELL TO THE WEST OF THE MARIANAS. OF NOTE, THE ASCAT PASS 
VERIFIED THE 1200Z GFS MODEL FORECAST POSITION AND WIND FIELD WITH 
HIGH CONFIDENCE, LENDING INCREASED CONFIDENCE TO THE GFS FORECAST. 
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. 
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE 
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE 
WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH. SEE REF A (WTPN21 PGTW 
211230) 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.
3. JUSTIFICATION FOR REISSUE: UPGRADED AREA IN PARA 1.B.(1). TO 
HIGH.//
NNNN