WDPN32 PGTW 281500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W WARNING NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM 15W (TALAS), LOCATED APPROXIMATELY 745 NM SOUTH 
OF TOKYO, JAPAN, HAS TRACKED NORTH-NORTHEASTWARD AT 02 KNOTS OVER THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND A 281117Z 
METOP-A IMAGE INDICATE A SLOWLY CONSOLIDATING LOW-LEVEL CIRCULATION 
CENTER (LLCC) WITH DEEP CONVECTIVE BANDING WRAPPING FROM THE 
SOUTHWEST QUADRANT INTO THE NORTHEAST QUADRANT. A 281117Z PARTIAL
ASCAT IMAGE DEPICTS A STRONGER, MORE TIGHTLY-WRAPPED WIND FIELD WITH 
NUMEROUS 45 KNOT WIND VECTORS AROUND THE CENTER. THE CURRENT POSITION
IS BASED ON THE RECENT ASCAT IMAGERY WITH FAIR CONFIDENCE. THE 
CURRENT INTENSITY IS ASSESSED SLIGHTLY HIGHER THAN THE DVORAK 
ESTIMATES OF 45 KNOTS.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.
   B. TS 15W REMAINS EMBEDDED WITHIN A COMPETING STEERING 
ENVIRONMENT BETWEEN THE SUBTROPICAL RIDGE (STR) POSITIONED OVER 
JAPAN AND THE NEAR-EQUATORIAL RIDGE POSITIONED TO THE SOUTH. AS TS 
15W STRENGTHENS OVER THE NEXT 24-48 HOURS, THE PERIPHERAL RIDGE IS 
FORECAST TO BUILD PROVIDING A STRONGER POLEWARD STEERING INFLUENCE 
THROUGH TAU 72. ALL AVAILABLE DYNAMIC MODEL GUIDANCE SUPPORTS THIS 
SCENARIO WITH SIMILAR TRACK SPEEDS AMONG THE DIFFERENT MODEL 
SOLUTIONS. THERE IS STILL A MARKED DISPARITY IN THE TRACK WITH A 175 
NM SPREAD AT TAU 72. THE DIFFERENCE IS PRIMARILY DUE TO THE TIMING 
OF THE TURN NORTH-NORTHWESTWARD. THE JGSM, GFS AND NOGAPS MODELS 
INDICATE A CONTINUED SLOW TRACK NORTHEASTWARD THROUGH TAU 24 WHILE 
UKMO, ECMWF, GFDN AND WBAR INDICATE A SHARPER, EARLIER TURN. UPPER-
LEVEL ANALYSIS AND WATER VAPOR IMAGERY SHOW GOOD POLEWARD AND 
EQUATORWARD OUTFLOW AND ALSO INDICATE THAT THE UPPER-LEVEL CYCLONE 
THAT HAD PERSISTED OVER THE LLCC, HINDERING CONVECTIVE DEVELOPMENT, 
IS WEAKENING ALLOWING FOR IMPROVED ORGANIZATION OVER THE PAST 12 
HOURS. THEREFORE, TS 15W IS FORECAST TO INTENSIFY TO A PEAK 
INTENSITY OF 75-80 KNOTS BY TAU 72. 
    C. THE STR OVER JAPAN IS FORECAST TO WEAKEN AFTER TAU 72 
ALLOWING THE SYSTEM TO ACCELERATE NORTHWARD AHEAD OF AN UPPER-LEVEL 
TROUGH. DYNAMIC MODEL GUIDANCE AND ENSEMBLE GUIDANCE INDICATES A 
HIGH PROBABILITY THAT THE SYSTEM CENTER WILL MAKE LANDFALL OVER 
CENTRAL JAPAN AFTER TAU 120. BASED ON MICROWAVE IMAGERY AND ASCAT, 
TS 15W IS A 250-300 NM RADIUS SYSTEM WITH EXTENSIVE GALE FORCE WINDS 
EXTENDING OUT TO 180 NM. TS 15W IS FORECAST TO WEAKEN SLIGHTLY AS IT 
APPROACHES JAPAN DUE TO INCREASING (MODERATE) VERTICAL WIND SHEAR.//
NNNN