WDPN31 PGTW 101500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 039//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.7N 126.0E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 248 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE
EMERGENCE OF DEEP, OVERSHOOTING CLOUD TOPS WRAPPING INTO THE
LOW-LEVEL CIRCULATION CENTER. THE DEVELOPING CORE IS FLANKED BY A
MASSIVE OUTER CONVECTIVE BAND THAT STRETCHES 330 NM FROM END TO
END. THE SYSTEM EXHIBITS EXCELLENT RADIAL OUTFLOW, WHICH HAS
RECENTLY EXPANDED FURTHER ALONG THE POLEWARD SIDE. A 100929Z WSF-M
MWI 37 GHZ MICROWAVE IMAGE REVEALS A CLOSED LOW-LEVEL RING
SURROUNDING THE INNER CORE, BUT THE 89 GHZ CHANNEL SHOWS THIS SAME
FEATURE OPEN ON ITS SOUTH SIDE. WITH THE INNER CORE NOW
CONSOLIDATING ON EIR IMAGERY, IT HAS BECOME CLEAR THAT THE SYSTEM
DID NOT UNDERGO A FULL, TRADITIONAL EYEWALL REPLACEMENT CYCLE
(ERC). INSTEAD, THE CONVECTIVE STRUCTURE NOW RESEMBLES A BANDING
EYE FORMATION, CHARACTERIZED BY A PROMINENT SPIRAL BAND CONVERGING
INWARD TOWARD A FORMATIVE EYE. THE SYSTEM IS IN A FAVORABLE
ENVIRONMENT OF VERY LOW VERTICAL WIND SHEAR (VWS) AND WARMER SEA
SURFACE TEMPERATURES (SST). DATA FROM AN RCM-1 SAR PASS AT 100938Z
AND AN ASCAT-B PASS AT 101152Z CONFIRM THAT THE STRONGEST WINDS ARE
STILL LOCATED WITHIN THE OUTER BAND, ROUGHLY 60 NM FROM THE CENTER,
THOUGH THE OVERALL WIND FIELD HAS BECOME SIGNIFICANTLY LESS
SYMMETRIC. THE CIRCULATION REMAINS MASSIVE, WITH GALE-FORCE WINDS
EXTENDING BEYOND 300 NM FROM THE CENTER AND STORM-FORCE WINDS OUT
TO AS FAR AS 230 NM. PEAK OBSERVED WIND GUSTS HAVE CLIMBED TO OVER
60 KTS IN SOME PARTS OF THE SOUTHERN RYUKYU ISLANDS. THE INITIAL
POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE ASCAT-B
IMAGE. THE IMPROVED CONVECTIVE SIGNATURE, RISING SUBJECTIVE DVORAK
ESTIMATES RANGING FROM T4.5 TO T5.0, AND SAR DATA JUSTIFY RAISING
THE INITIAL INTENSITY TO 80 KT WITH MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   CIMSS ADT: 49 KTS AT 101050Z
   CIMSS AIDT: 48 KTS AT 101050Z
   CIMSS D-MINT: 82 KTS AT 100847Z
   CIMSS D-PRINT: 66 KTS AT 101050Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 27-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: AFTER A BRIEF NORTHWARD JOG, TY BAVI HAS
RESUMED ITS EXPECTED NORTHWESTWARD TRAJECTORY. STEERED BY A
DEEP-LAYER STR POSITIONED SOUTH OF HONSHU, THE SYSTEM WILL MAINTAIN
THIS MOTION, PASSING VERY NEAR OR DIRECTLY OVER THE SOUTHERN
JAPANESE ISLAND OF ISHIGAKI BEFORE MAKING LANDFALL OVER WENZHOU,
CHINA. A FINAL TURN TOWARDS THE NORTH WILL OCCUR AT TAU 60 AS THE
CIRCULATION CROSSES THE LOW- TO MID-LEVEL RIDGE AXIS. THE
SUPPORTIVE CONDITIONS OF LOW VWS AND WARM SST WILL PREVAIL OVER THE
NEXT 24 HOURS, HELPING THE SYSTEM TO MAINTAIN ITS INTENSITY THROUGH
LANDFALL. POTENTIAL PARTIAL ERC EVENTS MAY CAUSE FLUCTUATIONS IN
TRACK AND INTENSITY ON FINAL APPROACH TO MAINLAND CHINA. RAPID
WEAKENING WILL COMMENCE ONCE THE SYSTEM MOVES INLAND, WITH
DISSIPATION PREDICTED BY TAU 60. EVEN AFTER THE CENTER OF THE
SYSTEM MOVES FAR INLAND, THE MASSIVE SCALE OF THE CIRCULATION MEANS
A BROAD FETCH OF ELEVATED WINDS WILL TRAVEL NORTHWARD OVER THE
OFFSHORE WATERS OF CHINA AND PUSH INTO THE YELLOW SEA.

MODEL DISCUSSION: MODELS PRESENT A TIGHT GUIDANCE ENVELOPE THROUGH
TAU 60, WITH THE AI TRACKERS COMPRISING THE POLEWARD SIDE OF THE
ENVELOPE. THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE
SLIGHTLY POLEWARD OF THE CONSENSUS, SLIGHTLY HEDGED TOWARDS THE
AVERAGE OF THE AI TRACKERS. THE GFS, HAFS-A, AND THE EXPERIMENTAL
DEEPMIND SOLUTIONS DEPICT A RELATIVELY FLAT INTENSITY TREND THROUGH
TAU 12-24, FOLLOWED BY RAPID WEAKENING THEREAFTER. THE JTWC
INTENSITY FORECAST AGREES WITH THIS PHILOSOPHY AND TRACKS CLOSELY
WITH THESE SOLUTIONS THROUGH TAU 60.

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