WDPN31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.5N 138.4E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 842 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 09W
(BAVI) WITH IMPROVING SYMMETRY IN THE CENTRAL DENSE OVERCAST THAT
IS SURROUNDING THE EYEWALL COMPARED TO 6 HOURS AGO. THE EYE HAS
ALSO NOTABLY EXPANDED WITH STEADILY IMPROVING DEFINITION AFTER
RECOVERING FROM AN EYEWALL REPLACEMENT CYCLE (ERC). THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE DEFINED EYE IN
ANIMATED MSI. THE INITIAL INTENSITY OF 125 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND CIMSS INTENSITY
ESTIMATES LISTED BELOW. ENVIRONMENTAL ANALYSIS INDICATES THAT 09W
IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE RADIAL
OUTFLOW ALOFT, LOW TO MODERATE (15-20 KTS) NORTHEASTERLY SHEAR, AND
WARM (29-30 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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: T6.0 - 115 KTS
   CIMSS SATCON: 137 KTS AT 070500Z
   CIMSS ADT: 124 KTS AT 070600Z
   CIMSS AIDT: 115 KTS AT 070600Z
   CIMSS D-MINT: 125 KTS AT 070356Z
   CIMSS D-PRINT: 120 KTS AT 070600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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 09W IS FORECAST TO CONTINUE TRACKING
WEST-NORTHWESTWARD UNDER THE INFLUENCE OF A SIMILAR STEERING
MECHANISM THROUGH TAU 24. AFTER TAU 24, THE STR THAT IS CURRENTLY
CENTERED OVER OKINAWA IS EXPECTED TO SLIDE EASTWARD AND MERGE WITH
ANOTHER RIDGE THAT IS CURRENTLY POSITIONED TO THE EAST-NORTHEAST OF
09W. THIS RESULTING STR WILL GUIDE 09W MORE NORTHWESTWARD AS THE
SYSTEM TRACKS ALONG THE WESTERN EXTENT OF IT. THE SYSTEM IS
FORECAST TO TRACK VERY CLOSE TO ISHIGAKIJIMA NEAR TAU 84 AS IT
HEADS TOWARD THE EASTERN COAST OF CHINA. A FINAL LANDFALL IS
CURRENTLY FORECAST TO OCCUR BETWEEN TAUS 96 AND 120, WELL SOUTH OF
SHANGHAI. IN TERMS OF INTENSITY, 09W IS FORECAST TO SLIGHTLY
INTENSIFY OVER THE NEXT 12 HOURS AS THE SYSTEM RECOVERS FROM THE
ERC AND THE ENVIRONMENT REMAINS FAVORABLE. AFTER TAU 12,
NORTHEASTERLY SHEAR IS EXPECTED TO INCREASE TO 20-30 KTS THROUGH
TAU 48, CAUSING THE SYSTEM TO GRADUALLY WEAKEN. ONCE THE SYSTEM
TRACKS EAST AND NORTH OF TAIWAN, SEA SURFACE TEMPERATURES WILL
SLIGHTLY COOL AND OCEAN HEAT CONTENT WILL CONSIDERABLY LOWER,
FURTHER SUPPORTING A WEAKENING TREND AS 09W APPROACHES THE 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 WITH THE EXCEPTION OF NAVGEM, WHICH TRACKS THE SYSTEM
FURTHER TO THE SOUTH THAN THE REMAINDER OF GUIDANCE. DISREGARDING
NAVGEM, THERE IS A 90 NM CROSS-TRACK SPREAD AT TAU 72, WHICH OPENS
UP TO 205 NM AT TAU 120. THE VARIOUS AI MODELS COMPRISE THE
NORTHERNMOST MODELS, WHILE THE ECMWF DETERMINISTIC IS THE
SOUTHERNMOST MODEL, AND ACTUALLY CLIPS THE NORTHERN COAST OF
TAIWAN. THE JTWC TRACK FORECAST IS PLACED A TOUCH TO THE NORTH OF
THE CONSENSUS WITH OVERALL HIGH CONFIDENCE. INTENSITY GUIDANCE
GENERALLY AGREES ON A STEADY INTENSITY THROUGH TAU 24 FOLLOWED BY
GRADUAL WEAKENING THROUGH TAU 96. THE PRIMARY OUTLIER IS THE DECAY
SHIPS, WHICH SHOWS A SIGNIFICANTLY FASTER RATE OF WEAKENING. THE
JTWC INTENSITY FORECAST IS PLACED NEAR THE CONSENSUS WITH 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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