WDPN31 PGTW 100900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 038//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.9N 126.9E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 280 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE
TYPHOON (TY) STRUGGLING TO MAINTAIN A COHERENT INNER-CORE
STRUCTURE. A CONCENTRIC RING MEASURING 170 NM IN DIAMETER IS UNABLE
TO CLOSE OFF ON THE NORTHWEST SIDE. THIS PERSISTENT OPENING IS
ENABLING CENTRAL CONVECTION TO FLARE UP AND SUSTAIN THE PARTIAL
INNER CORE, INDICATING THAT THE EYEWALL REPLACEMENT CYCLE (ERC) IS
STALLED AND IS UNLIKELY TO COMPLETE IN THE NEAR TERM. THE OUTFLOW
PATTERN IS UNUSUAL NEAR THE CENTER. WHILE LOW VERTICAL WIND SHEAR
(VWS) IS SUPPORTING HEALTHY RADIAL OUTFLOW, CIRRUS CLOUDS ON THE
INNER EDGE OF THE CONCENTRIC RING ARE OBSERVED FLOWING INWARD AND
DISSIPATING. THIS INWARD FLOW STRONGLY INDICATES SUBSIDENCE
OCCURRING WITHIN THE MOAT REGION BETWEEN THE INNER CORE AND THE
PARTIAL OUTER EYEWALL. TROPOSPHERIC CONDITIONS REMAIN SUPPORTIVE OF
THE BROAD SYSTEM, CHARACTERIZED BY LOW VWS AND ABUNDANT DEEP-LAYER
MOISTURE. THE OCEAN ENVIRONMENT IS MORE CHALLENGING TO EVALUATE
BECAUSE THE EXTENSIVE CLOUD SHIELD AND PRECIPITATION HINDER
ACCURATE SATELLITE-DERIVED MEASUREMENTS OF SEA SURFACE TEMPERATURE
(SST) AND OCEAN HEAT CONTENT (OHC). HOWEVER, IT IS PROBABLE THAT
THE COMBINATION OF COOL WATER UPWELLING AND THE ENERGY-DISPERSIVE
NATURE OF THE PROLONGED ERC HAS PREVENTED THE TYPHOON FROM
INTENSIFYING. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE SPIRAL CONVECTIVE BANDING AND THE TIGHT GROUPING OF
AGENCY SATELLITE FIXES. THE INITIAL INTENSITY IS HELD AT 75 KTS
WITH MEDIUM CONFIDENCE ON A BLEND OF THE SUBJECTIVE DVORAK
ESTIMATES RANGING FROM T4.0 TO T5.0 AND D-PRINT. THE SYSTEM
FEATURES A MASSIVE WIND FIELD, WITH GALE-FORCE WINDS EXTENDING
BEYOND 300 NM FROM THE CENTER AND STORM-FORCE WINDS UP TO 200 NM
OUT. THE OUTER CONVECTIVE RING ROUGHLY DEMARCATES THE LATERAL
EXTENT OF SUSTAINED STORM-FORCE WINDS. GROUND OBSERVATIONS FROM THE
SOUTHERN JAPANESE ISLANDS OF SHIMOJISHIMA AND OKINAWA REPORT WIND
GUSTS APPROACHING 50 KTS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
STR SOUTH OF HONSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 71 KTS AT 100020Z
   CIMSS ADT: 53 KTS AT 100600Z
   CIMSS AIDT: 52 KTS AT 100600Z
   CIMSS D-MINT: 78 KTS AT 092302Z
   CIMSS D-PRINT: 78 KTS AT 100600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-29 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 BEING STEERED TOWARDS THE NORTHWEST
BY A STR POSITIONED SOUTH OF HONSHU, EXHIBITING SOME SHORT-TERM
TRACK WOBBLING. THIS TRAJECTORY WILL PERSIST THROUGH LANDFALL OVER
CENTRAL CHINA AND SUBSEQUENT DISSIPATION OVER OR JUST EAST OF THE
YANGTZE RIVER DELTA BY TAU 72. FOR THE NEXT 24-36 HOURS, THE
SURROUNDING ATMOSPHERIC CONDITIONS WILL BE FAVORABLE DUE TO LOW VWS
AND RICH, DEEP-LAYER MOISTURE. DESPITE THESE SUPPORTIVE CONDITIONS,
THE EXCEPTIONALLY BROAD AND EXPANSIVE NATURE OF THE CIRCULATION
WILL PRECLUDE ANY SUBSTANTIAL INTENSIFICATION, COMPOUNDED BY THE
ONGOING UPWELLING OF COOLER SUBSURFACE OCEAN WATERS AND THE STALLED
ERC. EVEN IF THE OUTER EYEWALL MANAGES TO CONSOLIDATE AND COMPLETE
THE ERC WITHIN THE NEXT 24 HOURS, THE SYSTEM WILL HAVE A VERY
LIMITED, 12-HOUR WINDOW OF OPPORTUNITY TO TIGHTEN UP AND INTENSIFY
PRIOR TO LANDFALL. THEREFORE, THE FORECAST CALLS FOR A STEADY
INTENSITY TO BE MAINTAINED UP UNTIL LANDFALL. ONCE INLAND, RAPID
WEAKENING WILL OCCUR AS THE SYSTEM IS CUT OFF FROM ITS HEAT SOURCE
AND EXPERIENCES FRICTIONAL AND DRYING EFFECTS OVER THE TERRAIN OF
CENTRAL CHINA. HOWEVER, BECAUSE THE CIRCULATION IS SO MASSIVE, A
BROAD FETCH OF ELEVATED WINDS WILL PUSH NORTHWARD OVER THE OFFSHORE
WATERS OF CHINA AND INTO THE YELLOW SEA WELL AFTER THE CIRCULATION
HAS DISSIPATED.

MODEL DISCUSSION: THE FORECAST TRACK HAS BEEN ADJUSTED POLEWARD BY
20 NM TO ACCOUNT FOR A NORTHWARD JOG OBSERVED OVER THE PAST 6
HOURS. MODELS ARE IN TIGHT AGREEMENT THROUGHOUT THE ENTIRETY OF THE
FORECAST PERIOD, WITH THE AI TRACKERS ENCOMPASSING THE POLEWARD
SIDE OF THE GUIDANCE ENVELOPE. THE JTWC FORECAST TRACK HEDGES
SLIGHTLY POLEWARD OF THE MULTI-MODEL CONSENSUS. NEARLY ALL RELIABLE
INTENSITY AIDS PREDICT ZERO TO SLIGHT INTENSIFICATION THROUGH TAU
24, FOLLOWED BY RAPID WEAKENING THEREAFTER. THE JTWC INTENSITY
FORECAST REFLECTS THE CONSENSUS PROFILE, CLOSELY ALIGNING WITH THE
HAFS-A, HWRF, AND THE EXPERIMENTAL DEEPMIND SOLUTIONS.

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