WDPN31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (HAGUPIT) WARNING 
NR 41//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 22W (HAGUPIT), LOCATED APPROXIMATELY 408 NM 
EAST-NORTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST-
SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SMALL CONVECTIVE 
CELL OVER A NEARLY FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER 
(LLCC), WITH THE REMAINING DEEP CONVECTION NOW DISPLACED 
SIGNIFICANTLY EASTWARD. A 102101Z SSMIS 85 GHZ IMAGE INDICATES THIS 
DISPLACEMENT OF DEEP CONVECTION TO BE APPROXIMATELY 80 NM. THE 
CURRENT POSITION IS BASED ON THE LLCC IN MSI AND THE PGTW FIX WITH 
GOOD CONFIDENCE. THE INITIAL INTENSITY WAS MAINTAINED AT 35 KNOTS AS 
THE SYSTEM GRADUALLY WINDS DOWN. UPPER-LEVEL ANALYSIS INDICATES TS 
22W STILL HAS FAVORABLE POLEWARD OUTFLOW, HOWEVER, IT IS NOT 
SUFFICIENT TO OVERCOME UPPER LEVEL SUBSIDENCE IN THE SOUTHEASTERN 
QUADRANT AND INCREASING VERTICAL WIND SHEAR (VWS) AS LOW LEVEL 
NORTHEASTERLY WINDS ARE NOW COMPLETELY OUT OF PHASE WITH THE UPPER 
LEVEL. TS 22W IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY 
OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS HAGUPIT IS FORECAST TO TRACK WEST-SOUTHWESTWARD THROUGH THE 
FORECAST PERIOD UNDER THE INFLUENCE OF LOW-LEVEL NORTHEASTERLY FLOW. 
THE SYSTEM WILL CONTINUE TO WEAKEN IN RESPONSE TO MORE STABLE AIR 
AND CONTINUED VWS ASSOCIATED WITH THE NORTHEASTERLY SURGE. TS 22W IS 
EXPECTED TO MAKE LANDFALL OVER SOUTHERN VIETNAM BEFORE TAU 24 AND 
SHOULD DISSIPATE OVER LAND BY TAU 36. DYNAMIC MODEL GUIDANCE REMAINS 
IN TIGHT AGREEMENT WITH LANDFALL AND DISSIPATION, EXCEPT FOR HWRF 
WHICH CALLS FOR A MORE SOUTHERLY, OVER-WATER TRACK. THE GFS ENSEMBLE 
MEAN SOLUTION DENOTES LANDFALL, HOWEVER THE SPREAD OF THE MEMBERS 
REFLECTS THE POSSIBILITY THAT TS 22W COULD SKIRT THE VIETNAMESE 
COAST. GIVEN THE OVERALL GOOD MODEL AGREEMENT, THERE IS HIGH 
CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED CLOSE TO 
THE MULTI-MODEL CONSENSUS AND THE PRIOR FORECAST.//
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