Tropical Storm HALONG Advisory 11月9日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (HALONG) WARNING NR
026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (HALONG), LOCATED APPROXIMATELY 503 NM
NORTHEAST OF MINAMI TORI SHIMA, HAS TRACKED NORTHEASTWARD AT 12 KNOTS
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER WITH THE
MAJORITY OF CONVECTION SHEARED TO THE SOUTHEAST. THE CONVECTIVE
SIGNATURE OBSERVED IN A 081731Z SSMI 37 GHZ MICROWAVE IMAGE COVERING THE
WESTERN SEMI-CIRCLE LENDS GOOD CONFIDENCE TO THE INITIAL POSITION. THE
INITIAL INTENSITY OF 55 KTS IS PLACED BETWEEN A 081521Z SATCON ESTIMATE
OF 60 KTS AND DVORAK CURRENT INTENSITY ESTIMATES OF T2.5-3.0 (35-45 KTS)
FROM PGTW AND RJTD BASED ON A SLIGHTLY WEAKENING CONVECTION IN THE PAST
SIX HOURS. ADDITIONALLY, A 081910Z ADVANCED DVORAK TECHNIQUE ESTIMATE
ASSESSES THE INTENSITY AT 51 KTS, PLACING GOOD CONFIDENCE IN THE
OFFICIAL JTWC INITIAL INTENSITY. UPPER-LEVEL ANALYSIS REVEALS AN
UNFAVORABLE ENVIRONMENT WITH HIGH (30-40 KTS) WESTERLY VERTICAL WIND
SHEAR (VWS). HOWEVER, THIS IS OFFSET BY CONTINUED, GOOD POLEWARD OUTFLOW
FROM THE SYSTEM. SEA SURFACE TEMPERATURES ARE UNFAVORABLE AS THEY ARE
BELOW 26 DEGREES CELSIUS. TS 24W IS TRACKING WITHIN THE MIDLATITUDE
WESTERLY FLOW ALONG THE NORTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR). DESPITE THE SHEARED CONVECTION AND DEGRADING STRUCTURE, THE
SYSTEM IS ASSESSED AS TROPICAL AT THIS TIME.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 24W IS EXPECTED TO SHIFT TO AN EAST-NORTHEASTWARD TRACK AND
MAINTAIN THIS COURSE THROUGH THE REMAINDER OF THE FORECAST PERIOD. AS IT
TRANSITS, THE ENVIRONMENT WILL BECOME MORE UNFAVORABLE AS INCREASING VWS
AND COOLING SSTS BEGIN TO RAPIDLY WEAKEN THE SYSTEM. EXTRATROPICAL
TRANSITION (ETT) WILL BEGIN AROUND TAU 12 AS TS 24W BEGINS TO INTERACT
WITH THE BAROCLINIC ZONE. TS 24W IS EXPECTED TO WEAKEN TO 35 KTS BY TAU
24 AND COMPLETE ETT BY TAU 36. THE NUMERICAL MODELS ARE IN TIGHT
AGREEMENT, SUPPORTING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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