Tropical Storm CHOI-WAN Advisory Sat Jun 05

SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (CHOI-WAN)
WARNING NR 023//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 04W (CHOI-WAN), LOCATED APPROXIMATELY 267 NM
SOUTH-SOUTHWEST OF TAIPEI, TAIWAN, HAS TRACKED NORTHEASTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS A BROAD AREA OF CONVECTION ASSOCIATED WITH TS
04W IS NOW TOTALLY OFFSET TO THE SOUTHWEST FROM A FULLY EXPOSED LOW-
LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE USING THE MSI LOOP, EXTRAPOLATION FROM A 040221Z
METOP-B ASCAT IMAGE, AND THE PGTW SATELLITE FIX. THE INITIAL
INTENSITY OF 30KTS IS SET WITH GOOD CONFIDENCE BASED ON THE OVERALL
ASSESSMENT OF MULTIPLE AGENCY DVORAK ESTIMATES OF T1.5/25KTS FROM
PGTW, RJTD, ADT, AND SATELLITE CONSENSUS (SATCON) OF 38KTS,
REFLECTING THE WEAKENING STATE OF THE CYCLONE. THE SYSTEM RESIDES IN
A FAVORABLE ENVIRONMENT WITH GOOD WESTWARD AND EQUATORWARD OUTFLOW,
VERY WARM (30-31C) SEA SURFACE TEMPERATURES, AND LOW (05-10KTS)
VERTICAL WIND SHEAR (VWS) FROM THE NORTHEAST. THE CYCLONE IS
TRACKING ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR)
TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 04W WILL CONTINUE MOVING TO THE NORTHEAST ALONG THE
AFOREMENTIONED STR AND INTERACT SLIGHTLY WITH THE SOUTHERN PORTION
OF THE CHUNGYANG MOUNTAIN RANGE IN TAIWAN. BY TAU 24, THE SYSTEM
WILL BEGIN DISSIPATING AS IT INTERACTS WITH THE MEI-YU FRONTAL
BOUNDARY APPROACHING FROM THE WEST AND REACH FULL DISSIPATION BY TAU
36, OR POSSIBLY SOONER. NUMERICAL MODELS ARE IN TIGHT AGREEMENT FROM
24NM AT TAU 12 TO A MERE 74NM BY TAU 36, LENDING HIGH CONFIDENCE TO
THE JTWC TRACK FORECAST.//
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