WDPN32 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (BOLAVEN) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.2N 153.2E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 422 NM NORTH OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 29 KTS
   SIGNIFICANT WAVE HEIGHT: 55 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
RAPIDLY DETERIORATING SYSTEM, WITH SOUTHWESTERLY SHEAR NOW
BEGINNING TO TAKE ITS TOLL. 15W (BOLAVEN) IS STILL CHARACTERIZED AS
A TYPHOON BASED ON THE LATEST PHASE CLASSIFICATION DATA, BUT IS
CLEARLY BEGINNING THE EARLY PHASES OF EXTRATROPICAL TRANSITION
(ETT) AS IT RACES OFF TO THE NORTHEAST. A 131826Z SSMIS 36GHZ
MICROWAVE IMAGE REVEALS THAT THE LOW-LEVEL CIRCULATION CENTER
(LLCC) IS STILL VERY WELL-DEFINED, WITH A MICROWAVE EYE FEATURE
STILL EVIDENT, THOUGH THIS FEATURE IS BEGINNING TO ELONGATE INTO A
MORE OBLONG SHAPE. HOWEVER, THE 89GHZ IMAGERY INDICATES THAT THE
UPPER-LEVEL CIRCULATION HAS COMPLETELY SHEARED APART. THE INITIAL
POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE MICROWAVE
EYE FEATURE DESCRIBED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON AN EXTRAPOLATION OF AN EARLIER
SENTINEL-1 SAR PASS COMBINED WITH THE MOST RECENT OBJECTIVE AND
SUBJECTIVE FIX ESTIMATES. AS WOULD BE EXPECTED AT THIS LATITUDE,
THE ENVIRONMENT IS NOT SUPPORTIVE OF TROPICAL CYCLONE DEVELOPMENT,
WITH SHEAR NOW ESTIMATED AT NEAR 45 KNOTS, AND SSTS ARE RAPIDLY
DROPPING OFF AS THE SYSTEM APPROACHES THE 26C ISOTHERM, WHILE
UPPER-LEVEL OUTFLOW CONTINUES TO BE EXTREMELY STRONG.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   CIMSS SATCON: 86 KTS AT 131606Z
   CIMSS ADT: 63 KTS AT 131730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 40-45 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON BOLAVEN CONTINUES TO VERY RAPIDLY
TRANSLATE TO THE NORTHEAST ALONG THE TIGHT GRADIENT FLOW ON THE
NORTHWEST SIDE OF A DEEP-LAYER STR CENTERED TO THE EAST-SOUTHEAST.
NO MAJOR CHANGES ARE EXPECTED IN THE STEERING FLOW AND THE SYSTEM
IS FORECAST TO TRACK NORTHEAST AT ABOUT 40 KNOTS THROUGH THE SHORT
DURATION OF THE FORECAST PERIOD. THE SYSTEM HAS ALREADY STARTED THE
EXTRATROPICAL TRANSITION (ETT) PHASE, AND IS EXPECTED TO COMPLETE
TRANSITION TO A TYPHOON STRENGTH, WARM-CORE SECLUSION TYPE,
EXTRATROPICAL LOW WITHIN THE NEXT 24 HOURS. THE INTENSITY, HAVING
DROPPED PRECIPITOUSLY OVER THE LAST 24 HOURS, WILL DROP OFF MORE
SLOWLY OVER THE NEXT 24 HOURS, AS THE SYSTEM STARTS TO TAP INTO
STRONG BAROCLINIC FORCING, WITH THE INTENSITY EXPECTED TO 70 KNOTS
AT THE END OF THE FORECAST PERIOD.  

MODEL DISCUSSION: TRACK GUIDANCE IS IN EXTREMELY TIGHT AGREEMENT,
BOTH IN TERMS OF THE ALONG-TRACK AND CROSS-TRACK SPREAD, PROVIDING
HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. INTENSITY GUIDANCE IS
ALSO IN GOOD AGREEMENT, THOUGH WITH MORE UNCERTAINTY IN THE PACE OF
WEAKENING. THE JTWC FORECAST IS ON THE HIGHER END OF THE GUIDANCE
PACKAGE, WITH MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
NNNN