WDPN31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR
029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.9N 134.1E
   INITIAL INTENSITY: 135 KTS
   GEOGRAPHIC REFERENCE: 674 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 52 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPANDING
AND CLEARING EYE THAT HAS BECOME MORE SYMMETRIC WITH A BETTER
DEFINED EYEWALL OVER THE PAST FEW HOURS. ENHANCED INFRARED IMAGERY
ALSO REVEALS WARMING TEMPERATURES WITHIN THE EYE. EARLIER, ANIMATED
HIGH-RESOLUTION HIMAWARI-9 VISIBLE IMAGERY SHOWED TWO MESOVORTICES
ORBITING ABOUT THE INNER EYEWALL, GENERATING A WAVENUMBER-2
ASYMMETRY. THE CENTRAL DENSE OVERCAST (CDO) SURROUNDING THE LARGE
EYE FEATURE REMAINS EXPANSIVE, WITH IMPROVED SYMMETRY OVER THE PAST
6 HOURS. A 072342 METOP-B ASCAT PASS REVEALED AN IMPRESSIVE
GALE-FORCE WIND FIELD IN EXCESS OF 500 NM DIAMETER AND FURTHER
HIGHLIGHTS THE SYMMETRY OF THE SYSTEM. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE CENTER OF THE EYE IN THE
MSI. THE INITIAL INTENSITY OF 135 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED PRIMARILY ON THE AGENCY DVORAK FIXES, SUPPORTED BY
THE CIMSS OBJECTIVE INTENSITY ESTIMATES. THE ENVIRONMENT IS
CHARACTERIZED AS FAVORABLE WITH HIGH SEA SURFACE TEMPERATURES
(29-30 C) AND ROBUST EQUATORWARD OUTFLOW ARE BEING OFFSET BY THE
PERSISTENT 20-25 KTS OF VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: SCATTEROMETER DATA AND OBJECTIVE BEST
TRACK

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

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T7.0 - 140 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T7.0 - 140 KTS
   KNES: T7.0 - 140 KTS
   CIMSS ADT: 134 KTS AT 080000Z
   CIMSS AIDT: 130 KTS AT 080000Z
   CIMSS D-MINT: 132 KTS AT 072135Z
   CIMSS D-PRINT: 135 KTS AT 080000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 25-30 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 (STY) 09W (BAVI) CONTINUED ON A
PRIMARILY WESTWARD TRACK OVER THE PAST 6 HOURS WITH A TRACK SPEED
OF 12 KTS. THE STR NOW CENTERED OVER KYUSHU THAT HAD PREVIOUSLY
BEEN THE PRIMARY STEERING INFLUENCE IS EXPECTED TO CONTINUE
MIGRATING EASTWARD AND MERGE WITH THE STR CENTERED TO THE NORTHEAST
OVER THE NEXT 36 HOURS. UNDER THIS STEERING REGIME, STY 09W IS
FORECAST TO MAINTAIN A WEST-NORTHWESTWARD TRAJECTORY OVER THE NEXT
12-18 HOURS BEFORE TURNING NORTHWESTWARD. THE FORECAST TRACK TAKES
THE CENTER OF THE SYSTEM JUST NORTHEAST OF TAIWAN AROUND 110600Z
BEFORE MAKING LANDFALL IN EASTERN CHINA. 09W IS EXPECTED TO RETAIN
AN EXPANSIVE (AROUND 500 NM DIAMETER) GALE-FORCE WIND FIELD UNTIL
IT MAKES LANDFALL. THE SYSTEM IS EXPECTED TO REMAIN SUPER TYPHOON
INTENSITY FOR THE NEXT 24 HOURS UNDER MOSTLY FAVORABLE
ENVIRONMENTAL CONDITIONS, WITH WARM SEA SURFACE TEMPERATURES, HIGH
OCEAN HEAT CONTENT, AND VERY GOOD OUTFLOW ALOFT. THE ONLY
ENVIRONMENTAL FACTOR RESTRAINING FURTHER INTENSIFICATION IN THE
NEAR TERM IS THE 20-25 KTS OF VWS. AFTER TAU 24, A MORE MODERATE
10-15 KTS OF VWS PERSISTS AND AIDS IN GRADUAL WEAKENING OF THE
SYSTEM, ESPECIALLY IN LIGHT OF THE GRADUAL LOWERING OF SSTS AND
LIKELY ADDITIONAL EYEWALL REPLACEMENT CYCLES (ERC). MORE RAPID
WEAKENING IS FORECAST BEGINNING AROUND TAU 72 AS THE SYSTEM
INTERACTS WITH THE ISLAND OF TAIWAN AND MAKES ITS EVENTUAL LANDFALL
OVER EASTERN CHINA.

MODEL DISCUSSION: MODEL TRACK GUIDANCE REMAINS IN GOOD AGREEMENT
ABOUT THE TURNING NORTHWESTWARD TRACK TURN, WITH A CROSS-TRACK
SPREAD OF 80 NM AT TAU 72 AS 09W BRUSHES PAST TAIWAN. THE
CROSS-TRACK SPREAD INCREASES TO 240 NM AT TAU 120 WHEN 09W WILL BE
WELL INLAND. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE THROUGH TAU 72 AND
MEDIUM CONFIDENCE THEREAFTER DUE TO THE UNCERTAINTY INTRODUCED BY
LAND INTERACTION. THE LATEST INTENSITY GUIDANCE REMAINS IN VERY
GOOD AGREEMENT ABOUT THE OVERALL WEAKENING TREND, WITH THE
EXCEPTION OF DECAY SHIPS WHICH SUGGESTS A MUCH FASTER WEAKENING
TREND. THE REMAINING GUIDANCE LIES WITHIN A 15 KT ENVELOPE AND THE
JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE MULTI-MODEL
CONSENSUS WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST PERIOD.

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