WDPN31 PGTW 030900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.9N 154.2E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 545 NM EAST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 39 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TY 09W HAS CONTINUED TO RAPIDLY INTENSIFY, INCREASING FROM 85 KTS
TO 105 KTS OVER THE PAST 6 HOURS. ANIMATED MULTISPECTRAL IMAGERY
(MSI) DEPICTS CONTINUALLY IMPROVING SYMMETRY, WITH A WELL-DEFINED
EYEWALL IN THE VISIBLE CHANNEL. THE DVORAK-ENHANCED INFRARED CHANNEL 
SHOWS A SYMMETRIC CENTRAL DENSE OVERCAST COMPLETELY SURROUNDING THE 
EYE AND WARMING TEMPERATURES WITHIN THE EYE. ANIMATED WATER VAPOR 
IMAGERY REVEALS ROBUST RADIAL OUTFLOW, UNINHIBITED IN THE CURRENT LOW 
SHEAR ENVIRONMENT. THE INITIAL POSITION IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON THE WELL-DEFINED EYE FEATURE IN MSI. THE INITIAL 
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SPREAD OF 
AGENCY DVORAK FIXES AND CIMSS OBJECTIVE INTENSITY AIDS. THE 
ENVIRONMENT IS CHARACTERIZED AS HIGHLY FAVORABLE FOR CONTINUED RAPID 
INTENSIFICATION, WITH LOW (5-10 KTS) DEEP-LAYER VERTICAL WIND SHEAR 
(VWS), VERY WARM (29-30C) SEA SURFACE TEMPERATURES, HIGH OCEAN HEAT 
CONTENT (OHC) EXCEEDING 110 KJ PER CM3, AND STRONG RADIAL OUTFLOW 
ALOFT.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) EXTENDING FROM SOUTH OF KYUSHU EASTWARD
INTO THE NORTHERN PACIFIC

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 98 KTS AT 030530Z
   CIMSS ADT: 102 KTS AT 030600Z
   CIMSS AIDT: 105 KTS AT 030600Z
   CIMSS D-MINT: 97 KTS AT 030329Z
   CIMSS D-PRINT: 109 KTS AT 030600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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: TYPHOON (TY) 09W (BAVI) HAS CONTINUED ON A
NEARLY WESTWARD TRACK UNDER THE STEERING INFLUENCE OF AN EXTENSION
OF THE STR CENTERED TO THE NORTHWEST. A BRIEF PERIOD OF WEAKENING
IN THE STEERING RIDGE AS A LONGWAVE TROUGH TRANSITS EASTWARD WELL
TO THE NORTH OF TY 09W IS EXPECTED TO SLOW THE SYSTEM'S SPEED OF
ADVANCE OVER THE NEXT 36 HOURS. THE CPA TO SAIPAN AND ROTA REMAINS
LITTLE CHANGED FROM THE PREVIOUS FORECAST, EXPECTED AROUND 052200Z.
THE ORIENTATION OF THE STR CURRENTLY ANCHORED SOUTH OF KYUSHU AND
ITS SLOW WESTWARD MIGRATION OVER THE NEXT 120 HOURS WILL RESULT IN
A PRIMARILY WESTWARD COMPONENT TO THE TRACK THROUGH TAU 36. AFTER
TAU 36 THE TRACK TURNS WEST-NORTHWESTWARD THROUGH THE REMAINDER OF
THE FORECAST PERIOD. RAPID INTENSIFICATION IF FORECAST TO CONTINUE
THROUGH TAU 36 TO A PEAK OF 150 KTS. AFTER TAU 36, VWS IS EXPECTED
TO STEADILY INCREASE TO 20 KTS AT TAU 60 AND 30-35 KNOTS BY TAU
120, STIFLING FURTHER INTENSIFICATION. THE PROBABILITY OF AN EYEWALL 
REPLACEMENT CYCLE (ERC) REMAINS HIGH, AS SUGGESTED BY HAFS-A, WHICH 
INTRODUCES SOME UNCERTAINTY IN THE TIMING AND MAGNITUDE OF THE PEAK 
INTENSITY. IN THE EVENT OF AN ERC, THE WIND FIELD IS EXPECTED TO 
EXPAND AND FURTHER LIMIT INTENSIFICATION.

MODEL DISCUSSION: MODEL TRACK GUIDANCE REMAINS IN A TIGHT ENVELOPE
THROUGH TAU 72, WITH THE EXCEPTION OF NAVGEM WHICH SUGGESTS A TRACK
SOUTH OF ROTA. THE REMAINDER OF GUIDANCE HAS A CROSS-TRACK SPREAD
OF 60 NM AT TAU 72 AND 75 NM AT TAU 120. TRACK SPEED IS SLIGHTLY
LESS CERTAIN IN THE LATER TAUS WITH AN ALONG-TRACK SPREAD OF 140 NM
AT TAU 120. THE JTWC TRACK FORECAST IS PLACED NEAR THE MULTI-MODEL
CONSENSUS WITH HIGH CONFIDENCE THROUGH TAU 72 AND MEDIUM CONFIDENCE
THEREAFTER. THERE IS LITTLE DEVIATION FROM THE PREVIOUS FORECAST
TRACK AS TY 09W APPROACHES THE NORTHERN MARIANA ISLANDS. MODEL 
INTENSITY GUIDANCE CONTINUES TO STRONGLY FAVOR RAPID INTENSIFICATION 
THROUGH TAU 36, THEN VARYING DEGREES OF GRADUAL WEAKENING THROUGH THE 
REMAINDER OF THE FORECAST PERIOD, OWING TO THE UNCERTAINTY ABOUT A 
POTENTIAL ERC. THE JTWC INTENSITY FORECAST IS PLACED ON THE HIGHER 
END OF THE GUIDANCE ENVELOPE WITH MEDIUM CONFIDENCE THROUGHOUT THE 
FORECAST PERIOD IN ANTICIPATION OF CONTINUED RAPID INTENSIFICATION.

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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