Tropical Storm KROVANH Advisory mié, 23-12

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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