WDPN32 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (BOLAVEN) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.0N 148.5E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 234 NM EAST-SOUTHEAST OF ANDERSEN AFB,
GUAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS MAINTAINED DEEP FLARING CENTRAL CONVECTION WITH FORMATIVE BANDS
INTERSECTING TOWARD AN OBSCURED LOW LEVEL CIRCULATION CENTER
(LLCC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
A 091114Z PARTIAL ASCAT PASS AND CORROBORATED BY A DOPPLER RADAR FIX
FROM NWS WFO GUAM. THE INITIAL INTENSITY IS ALSO PLACED WITH HIGH
CONFIDENCE BASED ON THE ASCAT IMAGE AND A RECENT SAR PASS AND
SUPPORTED BY AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE
OVERALL 6-HR SUSTAINED CONVECTIVE STRUCTURE.

INITIAL WIND RADII BASIS: SAR DATA.

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE NORTH AND NORTHEAST.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 53 KTS AT 091130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 15W WILL TRACK NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF AN EXTENSION THE STR TO THE NORTHEAST AND
WILL COME TO WITHIN 62NM OF ANDERSEN AFB AROUND 100700Z AS IT
TRACKS NORTHEAST OF GUAM. AFTER TAU 36, THE STR TO THE NORTH WILL
RECEDE EASTWARD, ASSUME STEERING AND DRIVE THE SYSTEM NORTHWARD
TOWARD IWO TO. THE FAVORABLE ENVIRONMENT WILL FUEL A STEADY THEN
RAPID INTENSIFICATION AS THE CYCLONE ROUNDS THE STR AXIS, FUELED BY
INCREASING POLEWARD OUTFLOW AHEAD OF A MID-LATITUDE TROUGH
APPROACHING FROM THE NORTHWEST, AND BY TAU 72 WILL PEAK AT 125KTS.
AFTERWARD, INCREASING VWS AND COOLING SST WILL RAPIDLY ERODE THE
SYSTEM DOWN TO 90KTS BY TAU 120. ALSO, AROUND TAU 96, BOLAVEN WILL
BEGIN EXTRA-TROPICAL TRANSITION, AND BY TAU 120, WILL TRANSFORM
INTO A HURRICANE-FORCE COLD-CORE LOW. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT WITH
A GRADUAL AND EVEN SPREAD TO A MERE 135NM BY TAU 72 THEN TO 165NM
BY TAU 120, LENDING HIGH CONFIDENCE TO THE JTWC TRACK. THERE IS ONLY 
MEDIUM CONFIDENCE IN THE INTENSITY FORECAST DUE TO UNCERTAINTIES 
RELATED TO RAPID INTENSIFICATION.


FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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