WDPN32 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (TALIM) WARNING NR 
10//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 06W (TALIM), LOCATED APPROXIMATELY 240 NM 
SOUTHWEST OF TAIPEI, TAIWAN, HAS TRACKED NORTHEASTWARD AT 12 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY SHOWS THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BEEN 
SEPARATED FROM DEEP CONVECTION BY OVER 60 NM FOR THE MAJORITY OF THE 
PAST SIX HOURS. RECENTLY, A REGION OF DEEP CONVECTION HAS BEEN 
BUILDING TO THE EAST OF THE LLCC. THE UPPER LEVEL SUBTROPICAL RIDGE 
(STR), LOCATED OVER SOUTHEASTERN CHINA, CREATING THE VERTICAL WIND 
SHEAR (VWS) OVER TS 06W HAS SLOWLY STARTED TO SHIFT TO THE 
SOUTHWEST. THE VWS IS BEGINNING TO WEAKEN ALLOWING THE DEEP 
CONVECTION TO SLOWLY BUILD ALONG THE SOUTHERN PERIPHERY. THE OVERALL 
STEERING ENVIRONMENT WILL CONTINUE TO TRACK THE LLCC TO THE 
NORTHEAST, TOWARDS THE TAIWAN STRAIT, AROUND THE NORTHWESTERN 
QUADRANT OF A DEEP LAYERED STR. THE INITIAL POSITION IS BASED ON THE 
EIR IMAGERY SHOWING THE FULLY EXPOSED LLCC. THE INITIAL INTENSITY 
HAS BEEN MAINTAINED AT 45 KNOTS BASED ON THE NOTED SHEARING OF DEEP 
CONVECTION WEAKENING AND THE CONVECTION BUILDING BACK TOWARDS THE 
LLCC. 
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 06W WILL STRUGGLE OVER THE NEXT 12 HOURS TO MAINTAIN 
INTENSITY AS VWS REMAINS AT MODERATE LEVELS (20 KNOTS). AS TS 06W 
MOVES TOWARDS THE TAIWAN STRAIT, IT IS EXPECTED TO MOVE OUT FROM 
UNDER THE STRONG NORTHEASTERLY FLOW AROUND THE STR AND INTO A REGION 
OF WEAKER UPPER LEVEL WINDS. DURING THIS TRANSITION PERIOD, 
SOUTHWESTERLY FLOW AROUND A STATIONARY UPPER LEVEL TROUGH IS 
EXPECTED TO INCREASE THE POLEWARD OUTFLOW CHANNEL BETWEEN TAU 12 AND 
24. THE SEA SURFACE TEMPERATURES WILL REMAIN FAVORABLE THROUGH TAU 
24 (26 TO 28 CELSIUS), WHEN COMBINED WITH THE BRIEF IMPROVEMENT IN 
THE POLEWARD OUTFLOW, WILL HELP TS 06W TO INTENSIFY. BEYOND TAU 36, 
THE MID-LATITUDE FLOW WILL CAUSE AN INCREASE IN COLD AIR ADVECTION 
WITHIN THE LOW- TO MID-LEVELS OF TS 06W, LEADING TO THE START OF THE 
EXTRA-TROPICAL TRANSITION (ETT) PROCESS. THE STEERING STR WILL BUILD 
CAUSING AN INCREASE IN TRACK SPEEDS OVER THE NEXT 24 HOURS, WITH 
INCREASING SPEEDS AS THE LLCC IS ABSORBED INTO THE BAROCLINIC ZONE 
ALONG THE EASTERN COAST OF JAPAN. FULL ETT TRANSITION IS EXPECTED BY 
TAU 48. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THE 
CURRENT FORECAST AS THE CONSENSUS HAS SHIFTED SOUTH IN LINE WITH THE 
CURRENT FORECAST REASONING.//
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