Tropical Storm KAI-TAK Advisory Wed Dec 20

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 32W (KAI-TAK)
WARNING NR 26//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 32W (KAI-TAK), LOCATED APPROXIMATELY 388 NM
EAST-SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED
SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY-EXPOSED
LOW-LEVEL CIRCULATION CENTER POSITIONED ALONG THE SOUTHEAST EDGE OF
AN AREA OF INTENSE CENTRAL CONVECTION, WHICH PROVIDES FAIR
CONFIDENCE IN THE INITIAL POSITION. MSI ALSO CONTINUES TO SHOW
STRONG NORTHERLY TO NORTH-NORTHEASTERLY LOW-LEVEL SURGE FLOW
ADVECTING STRATOCUMULUS ALONG THE WEST AND SOUTHWEST QUADRANTS OF
THE SYSTEM. A 200138Z ASCAT IMAGE AND SURFACE OBSERVATIONS INDICATE
35 TO 40 KNOT WINDS ASSOCIATED WITH THIS SURGE FLOW. THE INITIAL
INTENSITY REMAINS ASSESSED AT 35 KNOTS BASED ON THIS ASCAT DATA.
UPPER-LEVEL CONDITIONS REMAIN MARGINALLY FAVORABLE WITH LOW TO
MODERATE VERTICAL WIND SHEAR AND BROAD DIFFLUENCE. ADDITIONALLY, SST
VALUES REMAIN FAVORABLE AT 27 TO 28C. TS 32W IS TRACKING
SOUTHWESTWARD ALONG THE SOUTHEAST EDGE OF THE SURGE FLOW.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THE 34-KNOT WIND RADII ARE BASED ON A
DETAILED ANALYSIS OF THE AFOREMENTIONED ASCAT IMAGE.
   B. TS 32W IS FORECAST TO GRADUALLY TURN WEST-SOUTHWESTWARD WITHIN
THE NEXT 12 HOURS AS THE NORTHEAST SURGE BEGINS TO WEAKEN AND THE
EAST-WEST ORIENTED, LOW- TO MID-LEVEL SUBTROPICAL RIDGE ASSUMES THE
PRIMARY STEERING INFLUENCE. WITH THE EXCEPTION OF EGRR AND AFUM, THE
BULK OF THE DYNAMIC MODEL TRACKERS ARE IN GOOD AGREEMENT THROUGH TAU
72 AND SUPPORT THE JTWC FORECAST TRACK WITH GOOD CONFIDENCE. TS 32W
IS FORECAST TO MAINTAIN INTENSITY AT 35 KNOTS THROUGH TAU 24 UNDER
MARGINALLY-FAVORABLE ENVIRONMENTAL CONDITIONS. AFTER TAU 24, THE
SYSTEM SHOULD WEAKEN GRADUALLY AS NORTHEAST SURGE FLOW WEAKENS AND
EASTERLY VERTICAL WIND SHEAR HINDERS DEVELOPMENT. TS KAI-TAK WILL
DISSIPATE BY TAU 72 AS IT TRACKS OVER THE MALAY PENINSULA. OVERALL,
THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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