Tropical Storm KAI-TAK Advisory 12月21日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 32W (KAI-TAK)
WARNING NR 28//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 32W (KAI-TAK), LOCATED APPROXIMATELY 384
NM SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED SOUTHWESTWARD
AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS PERSISTENT BUT WARMING DEEP CONVECTION
DISPLACED TO THE WESTERN SEMI-CIRCLE OF A BROAD LOW-LEVEL
CIRCULATION. THE INITIAL POSITION IS BASED ON THE EIR LOOP WITH FAIR
CONFIDENCE. THE INITIAL INTENSITY OF 30 KNOTS IS BASED ON AN OVERALL
ASSESSMENT OF MULTI-AGENCY DVORAK ESTIMATES, SUPPORTED BY SURFACE
OBSERVATIONS, AND REFLECTS THE WEAKENED STATE OF THE CYCLONE.
UPPER-LEVEL CONDITIONS REMAIN MARGINALLY FAVORABLE WITH MODERATE
EASTERLY VERTICAL WIND SHEAR AND BROAD DIFFLUENCE. SST VALUES REMAIN
FAVORABLE AT 27 TO 28C. TD 32W IS TRACKING ALONG THE SOUTHEAST
PERIPHERY OF THE SUBTROPICAL RIDGE TO THE NORTHWEST AND IN-STREAM
WITH THE NORTHEASTERLY WIND SURGE IN THE SOUTH CHINA SEA.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 32W IS FORECAST TO GRADUALLY TURN WEST-SOUTHWESTWARD WITHIN
THE NEXT 12 HOURS AS THE NORTHEAST SURGE AND THE STR WEAKEN. THE
SYSTEM WILL MAINTAIN INTENSITY AT 30 KNOTS THROUGH TAU 12 UNDER
MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS. AFTERWARD, THE SYSTEM
SHOULD WEAKEN GRADUALLY AS NORTHEAST SURGE FLOW WEAKENS AND EASTERLY
VERTICAL WIND SHEAR INCREASES. TD KAI-TAK IS FORECAST TO DISSIPATE
OVER WATER BY TAU 36. DYNAMIC MODEL TRACKERS ARE IN GOOD AGREEMENT,
LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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