WDPN32 PGTW 220300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (BEBINCA) WARNING 
NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 05W (BEBINCA), LOCATED APPROXIMATELY 229 NM
SOUTHWESTWARD OF HONG KONG, HAS TRACKED WESTWARD AT 14 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) 
DEPICTS AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH AN AREA 
OF PERSISTENT DEEP CONVECTION DISPLACED OVER THE SOUTHWEST QUADRANT 
OF THE LLCC. A 212213Z SSMIS MICROWAVE IMAGE DEPICTS THE ISOLATED 
AREA OF DEEP CONVECTION SHEARED TO THE SOUTHWEST. THERE IS GOOD 
CONFIDENCE IN THE INITIAL POSITION BASED ON THE MSI ANIMATION AND 
SSMIS IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON 
RECENT PGTW AND KNES DVORAK INTENSITY ESTIMATES. UPPER LEVEL 
ANALYSIS INDICATES GOOD RADIAL OUTFLOW OFFSET BY STRONG (25 TO 30 
KNOT) NORTHEASTERLY VERTICAL WIND SHEAR (VWS). TS 05W IS TRACKING 
QUICKLY ALONG THE SOUTHERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE 
(STR) POSITIONED OVER SOUTHEAST CHINA.
3. FORECAST REASONING.
   A. THE FORECAST TRACK BETWEEN, TAU 24 AND TAU 48, HAS BEEN 
ALTERED FROM THE PREVIOUS FORECAST PHILOSOPHY AS THE MAJORITY OF THE 
DYNAMIC MODEL GUIDANCE INDICATES A STRONG NORTH-NORTHWEST TURN DUE 
TO A WEAKNESS IN THE DEEP STR. PREVIOUS FORECAST TRACKS WERE LAID IN 
CLOSE AGREEMENT WITH THE ECMWF SOLUTION, WHICH REMAINED VERY 
CONSISTENT AND SHOWED A NORTHWEST TRACK INTO NORTHERN VIETNAM UNDER 
A EAST-WEST ORIENTED STR. DUE TO THE WEAKNESS IDENTIFIED IN OTHER 
MULTIMODEL CONSENSUS (CONW) MEMBERS, THE CURRENT JTWC FORECAST TRACK 
IS LAID IN TIGHTER AGREEMENT WITH CONW AND THE GFS SOLUTION WITH A 
NORTH-NORTHWEST TURN AFTER TAU 24.
   B. TS 05W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD 
THROUGH TAU 12, ACROSS HAINAN, AND THEN GRADUALLY TURN NORTH-
NORTHWESTWARD AS IT TRACKS INTO A WEAK AREA OF THE STR. DYNAMIC 
MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 12, BUT THEN 
SPREADS SIGNIFICANTLY AS THE SYSTEM PASSES ACROSS NORTH HAINAN. THIS 
DISAGREEMENT AMONGST THE DYNAMIC MODELS APPEARS TO BE DUE TO THEIR 
REPRESENTATION OF A WEAKNESS IN THE STR. AS PREVIOUSLY DISCUSSED, 
THE CURRENT JTWC FORECAST TRACK IS LAID IN TIGHTER AGREEMENT WITH 
CONW AND THE GFS SOLUTION. TS 05W IS EXPECTED TO WEAKEN AFTER TAU 12 
DUE TO LAND INTERACTION AND THE CONTINUED STRONG VWS, REDEVELOP TO 
APPROXIMATELY 35 KNOTS ONCE BACK OVER WATER, AND THEN BEGIN 
DISSIPATING ONCE OVER LAND. THE SYSTEM SHOULD DISSIPATE OVER 
NORTHEAST VIETNAM BY TAU 48. OVERALL, THERE IS LOW CONFIDENCE IN THE 
JTWC FORECAST TRACK.//
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