WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 
027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.8N 136.7E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 764 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SUPER
TYPHOON 09W (BAVI) WITH AN EXPANSIVE RING OF COLD CLOUD TOPS
SURROUNDING A 30 NM EYE. ON THE BD CURVE IR SATELLITE LOOP, THE
BLACK SHADE NOW MEASURES A THICKNESS OF GREATER THAN 100 NM IN ALL
DIRECTIONS, SHOWING HOW LARGE THE SYSTEM HAS BECOME. OVERALL, THE
CENTRAL DENSE OVERCAST HAS SIGNIFICANTLY COOLED AND IS NOW MUCH
LARGER COMPARED TO 6 HOURS AGO. HOWEVER, THE EYE ITSELF HAS
SIMULTANEOUSLY BECOME A BIT MORE CLOUD-FILLED. THERE ALSO APPEARS
TO BE SOME PRESSURE ON THE SYSTEM FROM THE NORTHEAST, EVIDENT BY
THE UPPER-LEVEL CLOUD ELEMENTS AND ASSOCIATED OUTFLOW BEING
RESTRICTED IN THAT QUADRANT. THE INITIAL INTENSITY OF 130 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED PRIMARILY ON THE AGENCY
DVORAK CI ESTIMATES OF T6.5-T7.0. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE EYE IN ANIMATED EIR IMAGERY.
ENVIRONMENTAL ANALYSIS INDICATES THAT 09W IS IN A MARGINALLY
FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG OUTFLOW ALOFT AND
WARM (29-30 C) SEA SURFACE TEMPERATURES OFFSET BY THE MODERATE TO
HIGH (20-25 KTS) NORTHEASTERLY VERTICAL WIND SHEAR.

INITIAL WIND RADII BASIS: 071112Z METOP-B ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: A COMBINED STEERING INFLUENCE FROM THE
WESTERN EXTENSION OF A SUBTROPICAL RIDGE (STR) POSITIONED FAR TO
THE EAST-NORTHEAST AND A SEPARATE STR CENTERED OVER OKINAWA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T7.0 - 140 KTS 
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 123 KTS AT 071100Z
   CIMSS ADT: 127 KTS AT 071200Z
   CIMSS AIDT: 113 KTS AT 071200Z
   CIMSS D-PRINT: 110 KTS AT 071200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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: SUPER TYPHOON 09W IS FORECAST TO CONTINUE
TRACKING WEST-NORTHWESTWARD THROUGH TAU 24. AFTER TAU 24, THE STR
THAT IS CURRENTLY CENTERED OVER OKINAWA IS EXPECTED TO PROPAGATE
EASTWARD AND MERGE WITH THE STEERING COMPLEX THAT IS CURRENTLY
SITUATED TO THE EAST-NORTHEAST OF 09W. THE RESULTING STR WILL GUIDE
09W IN A MORE NORTHWESTWARD DIRECTION THROUGH THE REMAINDER OF THE
FORECAST PERIOD. A TRACK VERY CLOSE TO ISHIGAKIJIMA IS FORECAST TO
OCCUR JUST AFTER TAU 72 AS THE SYSTEM HEADS TOWARD THE EASTERN
COAST OF CHINA. A FINAL LANDFALL IS CURRENTLY FORECAST TO TAKE
PLACE WELL SOUTH OF SHANGHAI RIGHT AROUND TAU 96. IN TERMS OF
INTENSITY, 09W IS FORECAST TO SLIGHTLY INTENSIFY OVER THE NEXT 12
HOURS AS THE SYSTEM FENDS OFF THE ELEVATED NORTHEASTERLY SHEAR AND
RECOVERS FROM THE EYEWALL REPLACEMENT CYCLE THAT CONCLUDED SOME
10-12 HOURS AGO. AFTER TAU 12, THE SHEAR IS EXPECTED TO BEGIN
GRADUALLY DEGRADING THE VORTEX THROUGH TAU 36. AFTER TAU 36, THE
OCEAN HEAT CONTENT (OHC) WILL BEGIN TO MARKEDLY DROP, FURTHER
SUPPORTING A WEAKENING TREND. BY TAU 72, THE OHC WILL DROP TO
UNFAVORABLE LEVELS, CAUSING 09W TO WEAKEN AS IT APPROACHES THE
EASTERN COAST OF CHINA. AFTER LANDFALL, TERRAIN INTERACTION WILL
CAUSE THE SYSTEM TO RAPIDLY WEAKEN THROUGH THE REMAINDER OF THE
FORECAST PERIOD. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGHOUT THE FORECAST PERIOD WITH NO SIGNIFICANT
OUTLIERS THIS MODEL RUN. CROSS-TRACK SPREAD AT TAU 72 IS ABOUT 105
NM, WHICH INCREASES TO 205 NM AT TAU 120. THE ECMWF DETERMINISTIC
AND NAVGEM CONTINUE TO BE THE SOUTHERNMOST MODELS, SHOWING THE
VORTEX CLIPPING THE NORTHERN COAST OF TAIWAN. THE JTWC TRACK
FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS THROUGHOUT
THE FORECAST PERIOD WITH HIGH CONFIDENCE. INTENSITY GUIDANCE
GENERALLY AGREES ON A STEADY INTENSITY THROUGH TAU 24 FOLLOWED BY
GRADUAL WEAKENING THROUGH TAU 72. AFTER TAU 72, MODELS CONTINUE TO
AGREE ON A MORE RAPID RATE OF WEAKENING THROUGH TAU 120. THE
PRIMARY OUTLIER IS THE DECAY SHIPS, WHICH SHOWS A SIGNIFICANTLY
FASTER RATE OF WEAKENING OVER THE FIRST 72 HOURS. THE JTWC
INTENSITY FORECAST IS PLACED NEAR THE HAFS-A AND HWRF MODELS WITH
OVERALL MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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