WDPN32 PGTW 271500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W WARNING NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM 15W (TALAS), LOCATED APPROXIMATELY 760 NM
SOUTH OF TOKYO, JAPAN, HAS TRACKED NORTHWARD AT 02 KNOTS OVER THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY (IR) DEPICTS
A BROAD LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED CONVECTIVE
BANDING WRAPPING FROM THE SOUTHWEST INTO THE NORTHEAST QUADRANT.
UPPER-LEVEL ANALYSIS INDICATES GOOD OUTFLOW ALTHOUGH A SMALL CYCLONE 
IS EVIDENT OVER THE CENTER; THIS CYCLONE IS LIKELY INHIBITING THE 
FORMATION OF CENTRAL CONVECTION. THERE IS FAIR CONFIDENCE IN THE 
CURRENT POSITION BASED ON THE 271011Z SSMIS 37 GHZ IMAGE AND THE 
271140Z ASCAT IMAGE. THE CURRENT INTENSITY IS BASED ON DVORAK
ESTIMATES OF 45 KNOTS FROM ALL AGENCIES AND THE ASCAT DATA WHICH 
SHOWED 40-45 KNOT WINDS. 
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.
   B. TS 15W IS SITUATED BETWEEN THE SUBTROPICAL RIDGE (STR) OVER 
JAPAN AND THE NEAR-EQUATORIAL RIDGE, LOCATED SOUTH OF THE CENTER. AS 
A RESULT, TRACK MOTION HAS BEEN NEAR QUASI-STATIONARY OVER THE PAST 
12 HOURS. THE SYSTEM IS EXPECTED TO TRACK SLOWLY NORTHWWARD THROUGH 
THE PERIOD. TS 15W IS EXPECTED TO STRENGTHEN INTO A TYPHOON BY TAU 
48 UNDER IMPROVING UPPER-LEVEL CONDITIONS. AVAILABLE MODEL GUIDANCE 
IS IN FAIR AGREEMENT WITH THE EXCEPTION OF THE UKMO MODEL, WHICH 
SHOWS AN ERRONEOUS WESTWARD MOTION THROUGH TAU 72 ASSOCIATED WITH 
EXCESSIVE INTERACTION WITH TY 14W. THIS FORECAST IS POSITIONED EAST 
OF THE CONSENSUS TO OFFSET THE UKMO MODEL.
   C. IN THE EXTENDED TAUS, EVEN EXCLUDING THE UKMO SOLUTION, THERE 
IS STILL A WIDE DISPARITY IN THE MODEL GUIDANCE WITH A 330 NM SPREAD 
AT TAU 120, HOWEVER, MODEL GUIDANCE IS CONSISTENT IN INCREASING 
TRACK SPEEDS AFTER TAU 72 AS AN UPPER-LEVEL SHORT-WAVE TROUGH DIGS 
INTO JAPAN AND WEAKENS THE MID-LEVEL SUBTROPICAL RIDGE. TS 15W IS 
FORECAST TO INTENSIFY TO A PEAK OF 75-80 KNOTS AS POLEWARD OUTFLOW 
IMPROVES AHEAD OF THE UPPER-LEVEL TROUGH.//
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