WDPN31 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (HALONG) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
     TROPICAL STORM 24W (HALONG), LOCATED APPROXIMATELY 768 NM NORTH-NORTHWEST OF WAKE ISLAND, HAS TRACKED EASTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY-EXPOSED LOW LEVEL CIRCULATION CENTER WITH THE LIMITED REMAINING CONVECTION SHEARED TO THE SOUTHEAST. ADDITIONALLY, BASED ON SHALLOW BANDING SEEN IN A 090522Z SSMIS 37GHZ MICROWAVE IMAGE, THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS BASED ON A 090610Z ADVANCED DVORAK TECHNIQUE ESTIMATE OF 39 KNOTS. ENVIRONMENTAL ANALYSIS SHOWS THAT TS 24W EXISTS IN A REGION OF VERY HIGH (30-40 KTS) VERTICAL WIND SHEAR (VWS) AND LOW (LESS THAN 25 CELSIUS) SEA SURFACE TEMPERATURES (SST). ADDITIONALLY, THE POLEWARD OUTFLOW HAS NOW CUTOFF UPPER LEVEL SUPPORT FOR TS 24W. TS 24W IS TRACKING WITHIN THE MID-LATITUDE WESTERLY FLOW. TS 24W IS ASSESSED TO BE TRANSITIONING FROM A TROPICAL TO AN EXTRATROPICAL SYSTEM 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 WILL TRACK EAST-NORTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. AS THE SYSTEM TRANSITS, IT WILL RAPIDLY WEAKEN AS IT COMPLETES EXTRATROPICAL TRANSITION (ETT) AND INTERACTS WITH THE BAROCLINIC ZONE. ETT IS EXPECTED TO BE COMPLETE BY TAU 24. THE NUMERICAL MODELS ARE IN TIGHT AGREEMENT, SUPPORTING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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