WDPN31 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (KROVANH) 
WARNING NR 010//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 26W (KROVANH), LOCATED APPROXIMATELY
287 NM SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST-
SOUTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS WEAK, FRAGMENTED, AND 
FLARING CONVECTION SHEARED APPROXIMATELY 100NM NORTHWEST OF A RAGGED 
AND FULLY EXPOSED LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS 
PLACED WITH FAIR CONFIDENCE BASED ON THE LLC IN THE MSI LOOP. THE 
INITIAL INTENSITY OF 25KTS, CLASSIFIED AS TOO WEAK BY PGTW, IS BASED ON 
SURFACE WIND OBSERVATIONS FROM HUYEN TRAN ISLAND, 20NM TO THE NORTH. 
RECENT SCATTEROMETER DATA INDICATE A NARROW SWATH OF ELEVATED 30-35KT 
WINDS TO THE NORTHWEST ASSOCIATED WITH CONVERGENCE INDUCED BY A WIND 
SURGE IN THE SOUTH CHINA SEA AND COMPRESSED ALONG THE VIETNAMESE COAST. 
UPPER-LEVEL ANALYSIS REVEALS A MARGINAL ENVIRONMENT WITH MODERATE 
(15-20KT) VERTICAL WIND SHEAR (VWS) OFFSET BY STRONG POLEWARD OUTFLOW. 
SST VALUES (27-28C) REMAIN CONDUCIVE. THE SYSTEM IS TRACKING WEST-
SOUTHWESTWARD ALONG THE SOUTHEAST PERIPHERY OF A LOW-LEVEL 
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHWEST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TD KROVANH IS EXPECTED TO TRACK WESTWARD ALONG THE SOUTHERN 
PERIPHERY OF THE LOW-LEVEL STR THROUGH TAU 24. THE SYSTEM IS FORECAST 
TO HOLD ITS CURRENT INTENSITY UNDER THE MARGINAL CONDITIONS FOR 12HRS 
THEN WEAKEN STEADILY AS IT TRACKS INTO INCREASING VWS AND DIMINISHING 
UPPER LEVEL OUTFLOW. THE SYSTEM IS FORECAST TO DISSIPATE SOUTH OF 
VIETNAM BY TAU 24. NUMERICAL MODELS ARE IN GOOD AGREEMENT LENDING FAIR 
CONFIDENCE IN THE JTWC TRACK FORECAST.//
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