WDPN32 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (TRAMI) WARNING NR 
13//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 12W (TRAMI), LOCATED APPROXIMATELY 279 NM
SOUTHWARD OF KADENA AB, HAS TRACKED NORTHWARD AT 10 KNOTS OVER
THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY 
SHOWS A BAND OF DEEP CONVECTION PERSISTING ALONG THE SOUTHERN 
PERIPHERY OF THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE CURRENT 
POSITION IS BASED, WITH MODERATE CONFIDENCE, ON A 192121Z SSMIS 
IMAGE AND RECENT POSITION FIXES FROM PGTW AND RJTD, AND THE CURRENT 
INTENSITY OF 55 KNOTS IS CONSISTENT WITH RECENT DVORAK INTENSITY 
ESTIMATES FROM PGTW, RJTD, AND KNES. TS 12W IS MAKING A POLEWARD-TO-
WESTWARD TURN AS THE PRIMARY STEERING INFLUENCES SWITCHES FROM A 
STEERING RIDGE POSITIONED EAST OF THE SYSTEM A SUBTROPICAL RIDGE 
POSITIONED ACROSS THE EAST CHINA SEA AND WESTERN JAPAN.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE 
PREVIOUS PROGNOSTIC REASONING BULLETIN. 
   B. TS 12W IS EXPECTED TO TURN WESTWARD AS THE PRIMARY STEERING 
MECHANISM SWITCHES TO THE SUBTROPICAL RIDGE TO THE NORTH OVER THE 
NEXT 12 TO 24 HOURS. DYNAMIC MODEL GUIDANCE REMAINS IN GENERALLY 
GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD, ALTHOUGH THE JGSM, 
COAMPS-TC, GFDN, AND JAPANESE ENSEMBLE DEPICT A WESTWARD TRACK THAT 
LIES SLIGHTLY TO THE NORTH OF A GFS/NAVGEM/ECMWF/UKMET MODEL 
GROUPING. GIVEN THE ORIENTATION OF THE STEERING RIDGE AND STRONG 
EASTERLY STEERING FLOW TO THE NORTH, THIS FORECAST FAVORS THE 
SOUTHERN MODEL GROUPING AND LIES JUST SOUTH AND AHEAD OF THE MULTI-
MODEL CONSENSUS. GIVEN GOOD AGREEMENT BETWEEN THE CURRENT FORECAST, 
THE CURRENT MULTI-MODEL CONSENSUS, AND PREVIOUS FORECASTS, THERE IS 
HIGH CONFIDENCE IN THE FORECAST TRACK THROUGH TAU 72. TS 12W IS 
FORECAST TO SLOWLY INTENSIFY AS STRONG WESTWARD OUTFLOW ALOFT AND 
PASSAGE OVER WARM WATER OFFSET PERSISTENT EASTERLY VERTICAL WIND 
SHEAR OVER THE NEXT 36 HOURS. PASSAGE OVER LAND AFTER TAU 36 WILL 
HALT THE INTENSIFICATION TREND AND RESULT IN DISSIPATION AFTER THE 
SYSTEM MAKES LANDFALL IN CHINA.//
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