WDPN31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (PRAPIROON) WARNING 
NR 45//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 22W (PRAPIROON), LOCATED APPROXIMATELY 325 NM
SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN, HAS ACCELERATED NORTHEASTWARD AT
33 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
(EIR) SHOWS DEEP CENTRAL CONVECTION HAS UNRAVELED AND SHEARED NORTH
OF THE LOW LEVEL CIRCULATION CENTER. THIS IS ALSO EVIDENT ON A
181010Z SSMI-S MICROWAVE IMAGE. THE INITIAL POSITION IS BASED ON THE
EIR LOOP AND FROM THE SSMI-S IMAGE WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY IS BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND
RJTD. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS NOW EMBEDDED DEEP
IN THE BAROCLINIC ZONE NORTH OF THE RIDGE AXIS IN AN AREA OF STRONG
VERTICAL WIND SHEAR (VWS). THE CYCLONE IS TRACKING ALONG THE
NORTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE SOUTHEAST.  
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING BULLETIN.
   B. TS PRAPIROON HAS BEGUN EXTRA-TROPICAL TRANSITION AND WILL
CONTINUE TO ACCELERATE NORTHEASTWARD BECOMING A COLD CORE LOW BY TAU
24. CONVECTION WILL STEADILY DIMINISH WITH INCREASING VWS AND COOLING
SEA SURFACE TEMPERATURES. ADDITIONALLY, DRY MID-LEVEL AIR HAS BEGUN
TO ADVECT FROM THE NORTHWEST. MODEL GUIDANCE REMAINS TIGHT, LENDING
HIGH CONFIDENCE IN THE TRACK FORECAST.    //
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