WDPN32 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (PULASAN) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.7N 128.5E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 61 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 21 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
BROADLY CIRCULATING MONSOON DEPRESSION WITH SUBSIDENT DRY AIR
DESCENDING OVER THE CENTER, FULLY EXPOSING THE LOW-LEVEL
CIRCULATION CENTER (LLCC). THE SYSTEM IS POSITIONED FARTHER NORTH
THAN EXPECTED IN THE LAST WARNING. AS A RESULT, OKINAWA IS IN A MORE
FAVORABLE POSITION AWAY FROM THE MAXIMUM WIND BAND SPANNING 120NM TO 
255NM FROM CENTER. THE SYSTEM CONTINUES TO MAINTAIN THE 
CHARACTERISTICS OF A MONSOON DEPRESSION WITH DRY SUBSIDENT AIR IN THE 
CENTER, A BAND OF CONVECTION WRAPPING FROM THE EASTERN PERIPHERY, AND 
BROAD WIND RADII. THE INITIAL POSITION IS PLACED WITH MEDIUM 
CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED EIR REVEALING THE MID- 
AND UPPER-LEVEL CIRCULATION ON THE LEADING EDGE OF THE MONSOON 
DEPRESSION.  THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH LOW 
CONFIDENCE BASED ON PERSISTENCE AS THE DVORAK METHOD USED BY THE 
AGENCY FIXES LISTED BELOW STRUGGLES TO ACCURATELY ANALYZE MONSOON 
DEPRESSIONS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: AS THE LEADING EDGE OF THE MONSOON
DEPRESSION HAS PASSED, A SECONDARY FLOW ON THE BACKSIDE OF THE
BROAD CIRCULATION IS EXPECTED TO IMPACT OKINAWA WITHIN THE NEXT 12
HOURS.

FORECAST DISCUSSION: TROPICAL STORM (TS) 15W WILL CONTINUE TO TRACK
NORTHWESTWARD WHILE DRIVEN BY THE STR TO THE NORTH. THE STRONG
SOUTHWESTERLY FLOW SUPPORTING THE DRY CENTRAL CIRCULATION WILL
CONTINUE TO SUPPORT THE STRUCTURE OF THE MONSOON DEPRESSION
THROUGHOUT THE FORECAST PERIOD. AFTER PASSING SOUTH OF OKINAWA, THE
SYSTEM WILL MAKE LANDFALL QUICKLY FOLLOWING TAU 24. A SECONDARY
ENHANCED SOUTHERLY FLOW ON THE EASTERN PERIPHERY OF THE BROAD
CIRCULATION IS EXPECTED TO IMPACT OKINAWA WITHIN THE FIRST 12 HOURS
OF THE FORECAST. THE INTENSITY OF THE MONSOON DEPRESSION WILL
WEAKEN GRADUALLY AS THE SYSTEM MOVES AWAY FROM THE DEEP-LAYER
RIDGE, DECREASING THE SURFACE PRESSURE GRADIENT. SUBSIDENT
CONTINENTAL DRY AIR FED FROM THE WEST WILL CONTINUE TO ERODE THE
INTENSITY UNTIL THE SYSTEM MAKES LANDFALL AFTER TAU 24 AND RAPIDLY
DECLINES.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGHOUT THE FORECAST PERIOD THAT THE SYSTEM WILL TRACK
NORTHWESTWARD BY THE NORTHERN STR. AS THE SYSTEM SHALLOWS AFTER
LANDFALL IT WILL BE ABSORBED BY CLIMATOLOGICAL SOUTHWESTERLY FLOW
AFTER DISSIPATION. THE JTWC INTENSITY GUIDANCE IS IN STRONG
AGREEMENT REGARDING THE WEAKENING TREND THROUGHOUT THE FORECAST
PERIOD WITH THE EXCEPTION OF HWRF, WHICH INDICATED INTENSIFICATION
ABOVE 55KTS WITHIN THE NEXT 24 HOURS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: LOW//
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