WDPN31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 043//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.6N 121.8E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 327 NM WEST-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 52 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON 09W (BAVI) RETAINS A LARGE OUTER CONVECTIVE BAND WRAPPING
INTO THE CENTER, WHERE A SMALL EYE, VISIBLE ON ANIMATED ENHANCED
INFRARED (EIR) SATELLITE, IS STRUGGLING TO PERSIST. NOTABLY, A DRY
SLOT HAS BECOME APPARENT WITHIN THE GAP BETWEEN THE OUTER BAND AND
THE INNER CORE, INDICATING THAT DRIER AIR IS WRAPPING INTO THE
CIRCULATION FROM THE SOUTHWEST. THE SYSTEM IS RAPIDLY APPROACHING
MAINLAND CHINA WITH A FORWARD MOTION OF 16 KTS. WHILE THE IMMEDIATE
ATMOSPHERIC AND OCEANIC ENVIRONMENT REMAINS FAVORABLE,
CHARACTERIZED BY LOW VERTICAL WIND SHEAR (VWS) AND WARM SEA SURFACE
TEMPERATURE (SST), THE WINDOW OF OPPORTUNITY FOR THE STORM TO TAP
INTO THESE SUPPORTIVE CONDITIONS IS CLOSING. THE CIRCULATION CENTER
WILL IMMINENTLY CROSS THE COASTLINE BETWEEN THE NEIGHBORING CITIES
OF WENZHOU AND TAIZHOU. SURFACE OBSERVATIONS ALONG THE SOUTHERN
RYUKYU ISLANDS INDICATE THAT THE SUSTAINED GALE-FORCE WINDS HAVE
BECOME LESS WIDESPREAD, ESPECIALLY OVER SHIMOJISHIMA, AS THE SYSTEM
CONTINUES TO TRAVEL DOWNSTREAM. AN 110947Z RCM-1 SAR PASS REVEALED
MAXIMUM WINDS OF 80-85 KTS WITHIN THE NORTHEAST QUADRANT. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EYE
FEATURE OBSERVED IN EIR IMAGERY. THE INITIAL INTENSITY IS HELD AT
80 KTS WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE DVORAK
ESTIMATES OF T4.5-5.0 AND THE AFOREMENTIONED SAR PASS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED SOUTH OF HONSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 84 KTS AT 110750Z
   CIMSS ADT: 53 KTS AT 111200Z
   CIMSS AIDT: 59 KTS AT 111200Z
   CIMSS D-MINT: 88 KTS AT 110632Z
   CIMSS D-PRINT: 70 KTS AT 111200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 26-28 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: LAND INTERACTION

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 09W IS BEING STEERED NORTHWESTWARD BY A STR
TO THE EAST, A MOTION THAT WILL CONTINUE THROUGH TAU 36.
SUBSEQUENTLY, THE LOWER-LEVEL CIRCULATION (LLC) WILL CROSS THE
RIDGE AXIS AND BEGIN TO TURN POLEWARD. THE SYSTEM IS JUST ABOUT OUT
OF TIME OVER WATER AND WILL SHORTLY MAKE LANDFALL. RAPID WEAKENING
WILL OCCUR AS THE SYSTEM TRAVERSES OVER LAND NEAR THE YANGTZE RIVER
DELTA UNTIL DISSIPATION OCCURS AT TAU 48. DUE TO THE MASSIVE
SPATIAL EXTENT OF THE WIND FIELD, A BROAD FETCH OF ELEVATED WINDS
WILL PERSIST OFF THE CHINESE COASTLINE, PUSHING NORTHWARD INTO THE
YELLOW SEA. AN ALTERNATE SCENARIO EXISTS WHERE THE LLC SURVIVES ITS
JOURNEY OVER LAND AND EMERGES OVER THE WATERS OF THE YELLOW SEA
BEYOND TAU 48. SHOULD THIS OCCUR, THE SYSTEM WILL ACQUIRE
BAROCLINIC CHARACTERISTICS AS IT INTERACTS WITH A JET STREAM TO THE
NORTH, UNDERGOING EXTRATROPICAL TRANSITION AS IT CROSSES OVER THE
YELLOW SEA AND THE KOREAN PENINSULA.

MODEL DISCUSSION: THE MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH
TAU 24. BEYOND THIS PERIOD, THE CROSS-TRACK AND ALONG-TRACK SPREAD
INCREASE AT TAU 36 AND TAU 48 AS MODELS STRUGGLE TO HANDLE THE
TIMING OF THE SYSTEM'S INTERACTION WITH THE SYNOPTIC-SCALE FEATURES
OF THE MID-LATITUDES. WITH THE AI TRACKERS INTERMIXED WITH THE
PHYSICS-BASED MODELS, THE JTWC FORECAST TRACK STRICTLY FOLLOWS THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE THROUGH TAU 48. ALL
RELIABLE INTENSITY AIDS, INCLUDING HAFS-A, COAMPS-TC, GFS, AND
DEEPMIND, DEPICT RAPID WEAKENING UPON LANDFALL. THE JTWC INTENSITY
FORECAST CONCURS WITH THIS PHILOSOPHY, SHOWING A SHARP DECAY TO
DISSIPATION BY TAU 48.

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