WDPN32 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (BOLAVEN) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.4N 146.9E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 273 NM EAST-SOUTHEAST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) HAS RAPIDLY WEAKENED AS REVEALED IN ANIMATED ENHANCED
INFRARED (EIR) SATELLITE IMAGERY, WHICH SHOWS A HIGHLY ASYMMETRIC
CONVECTIVE CORE WITH THE BULK OF THE DEEP CONVECTION NOW DISPLACED
OVER THE NORTHEAST QUADRANT AND A CLOUD-FILLED EYE. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A MICROWAVE EYE
FEATURE IN THE 122246Z GMI 89 GHZ MICROWAVE IMAGE. ALTHOUGH TY 15W
IS GOING THROUGH AN EYEWALL REPLACEMENT CYCLE (ERC) WITH CONCENTRIC
EYEWALLS EVIDENT IN THE GMI IMAGE, INCREASING MIDLATITUDE WESTERLIES 
AND HIGH (25 KNOTS) VERTICAL WIND SHEAR (VWS) ARE TEARING THE SYSTEM 
APART SO ERC WILL NOT COMPLETE. SUBJECTIVE DVORAK FINAL-T ESTIMATES 
HAVE DECREASED AS LOW AS T5.5 (102 KTS) WITH DVORAK CURRENT INTENSITY
VALUES RANGING FROM 6.5 TO 7.5 (127-155 KTS). THE INITIAL INTENSITY
IS ASSESSED AT 125 KNOTS WITH MEDIUM CONFIDENCE BASED ON A 122009Z 
RCM2 SAR PASS INDICATING MAXIMUM WINDS OF 125 KNOTS, WHICH IS
CONSISTENT WITH THE RAPIDLY ERODING CONVECTIVE STRUCTURE AND THE PGTW,
KNES CURRENT INTENSITY ESTIMATES OF 127 KNOTS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST AND SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T7.5 - 155 KTS
   KNES: T6.5 - 127 KTS
   CIMSS ADT: 107 KTS AT 122330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINING INTO THE WESTERN SEMICIRCLE. 

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: TY 15W IS ACCELERATING NORTHEASTWARD ALONG THE
NORTHWESTERN PERIPHERY OF THE STR AND IS EXPECTED TO CONTINUE ON A
NORTHEASTWARD TRAJECTORY THROUGH THE FORECAST PERIOD WITH STEADY
WEAKENING DUE TO INCREASING VWS AND DRY AIR ENTRAINMENT. TY 15W
WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY TAU 12 AS IT BEGINS
TO INTERACT WITH THE BAROCLINIC ZONE. AFTER TAU 24, TY 15W WILL
WEAKEN RAPIDLY DUE TO STRONG VWS (40-60 KTS). TY 15W WILL COMPLETE
ETT BY TAU 48 AS IT GAINS FRONTAL CHARACTERISTICS AND TRACKS UNDER
THE JET WITH VWS IN EXCESS OF 70 KNOTS. THE SYSTEM IS FORECAST TO
REMAIN A HURRICANE FORCE EXTRA-TROPICAL LOW AS IT TRACKS SOUTH OF
THE ALEUTIAN ISLANDS.     

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN
EXCEPTIONALLY TIGHT AGREEMENT WITH AN 80 NM CROSS-TRACK SPREAD AND A 
105 NM ALONG-TRACK SPREAD AT TAU 48. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT AS WELL WITH RAPID WEAKENING INDICATED IN BOTH THE GLOBAL 
AND MESOSCALE MODELS.  

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