WDPN31 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (BAVI) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.3N 158.0E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 770 NM EAST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS PERSISTENT 
CONVECTIVE BANDING WRAPPING INTO THE CONSOLIDATING CENTRAL CORE OF TS 
09W. ALTHOUGH THE LOW-LEVEL CIRCULATION CENTER IS FULLY OBSCURED, THE 
SLACKENING VERTICAL WIND SHEAR (VWS) OVER THE PAST 6 HOURS SUGGESTS 
THAT THE VORTEX HAS BECOME BETTER ALIGNED VERTICALLY. ROBUST POLEWARD 
AND EQUATORWARD OUTFLOW IS EVIDENT IN ANIMATED WATER VAPOR IMAGERY, 
ALONG WITH IMPROVING RADIAL OUTFLOW OVER THE PAST FEW HOURS. A 020704Z 
WSFM 37 GHZ MICROWAVE IMAGE REVEALED A NASCENT MICROWAVE EYE WITH 
IMPROVED SYMMETRY OF THE CONVECTIVE BANDING SURROUNDING THE CENTRAL 
CORE. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON 
THE CENTER OF ROTATION IN ANIMATED EIR AND EXTRAPOLATION FROM THE 
EARLIER MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED 
WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE AGENCY DVORAK FIXES AND 
CIMSS OBJECTIVE INTENSITY ESTIMATES. THE ENVIRONMENT IS CHARACTERIZED 
AS HIGHLY FAVORABLE WITH VERY WARM (29-30 C) SEA SURFACE TEMPERATURES, 
HIGH OCEAN HEAT CONTENT, AND STRONG OUTFLOW ALOFT. THE ONLY LIMITING 
ENVIRONMENTAL FACTOR IN THE SHORT TERM IS THE 10-15 KTS OF EASTERLY 
VWS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SOUTHWESTERN FLANK OF AN EXTENSION OF
THE SUBTROPICAL RIDGE (STR) SITUATED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 55 KTS AT 021030Z
   CIMSS ADT: 59 KTS AT 021200Z
   CIMSS AIDT: 49 KTS AT 021200Z
   CIMSS D-MINT: 52 KTS AT 020840Z
   CIMSS D-PRINT: 57 KTS AT 021200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TROPICAL STORM (TS) 09W (BAVI) HAS CONTINUED
ON A NORTHWESTWARD TRACK OVER THE PAST 6 HOURS UNDER THE STEERING
INFLUENCE OF AN EXTENSION OF THE STR POSITIONED TO THE NORTHEAST.
THE SYSTEM IS EXPECTED TO ASSUME A WESTWARD TRAJECTORY THROUGH TAU
48 AS A STR CENTERED NEAR KYUSHU BUILDS IN FROM THE WEST AND TAKES
OVER AS THE PRIMARY STEERING MECHANISM. THE TRACK SPEED IS EXPECTED
TO SLOW BETWEEN TAU 24 AND TAU 72 UNDER THIS STEERING INFLUENCE AS
A LONGWAVE TROUGH PROPAGATES EASTWARD TO THE NORTH, TEMPORARILY
WEAKENING THE STEERING GRADIENT. AFTER TAU 60, TS 09W RETURNS TO A
WEST-NORTHWESTWARD TRACK AS IT APPROACHES THE NORTHERN MARIANA 
ISLANDS, WITH A CPA TO SAIPAN AROUND 052300Z. INTENSIFICATION OVER
THE NEXT 12 HOURS IS EXPECTED TO REMAIN STEADY AS THE SYSTEM 
CONSOLIDATES AND MOVES INTO A LOWER SHEAR ENVIRONMENT. AFTER TAU 12, 
ENVIRONMENTAL CONDITIONS FAVOR AN EXTENDED PERIOD OF RAPID 
INTENSIFICATION (RI) THROUGH TAU 60. HAFS-A CONTINUES TO DEPICT AN
EYEWALL REPLACEMENT CYCLE (EWRC) STARTING BETWEEN TAU 48 AND 60,
CONTINUING THROUGH PASSAGE TROUGH THE NORTHERN MARIANAS. AS A RESULT, 
THE INTENSITY IS FORECAST TO LEVEL OFF AT A PEAK OF 135 KTS FROM TAU 
72 THROUGH THE REMAINDER OF THE FORECAST PERIOD. 

MODEL DISCUSSION: WITH THE EXCEPTION OF THE UKMET ENSEMBLE MEAN AS
A SOUTHERN OUTLIER AND EC-AIFS AS THE NORTHERN OUTLIER, MODEL GUIDANCE 
HAS COME INTO CLOSER AGREEMENT WITH THE LATEST MODEL RUN, SHOWING A 
CROSS-TRACK SPREAD OF 50 NM AT TAU 72. OVERALL, THE GUIDANCE AGREES ON 
THE WEST-NORTHWESTWARD TRACK WITHOUT MUCH FURTHER SPREAD THROUGH THE 
END OF THE FORECAST PERIOD. THE JTWC TRACK FORECAST IS PLACED NEAR A 
MODIFIED MULTI-MODEL CONSENSUS THAT ACCOUNTS FOR THE OUTLIERS WITH 
HIGH CONFIDENCE THROUGHOUT THE FORECAST PERIOD. MODEL INTENSITY 
GUIDANCE STRONGLY FAVORS THE RAPID INTENSIFICATION SCENARIO WITH ALL 
MODEL SOLUTIONS DEPICTING VARYING DEGREES OF RI WITH THE EXCEPTION OF 
DECAY SHIPS. THE JTWC INTENSITY FORECAST IS PLACED ALONG THE MEAN OF 
THE REMAINING MODEL GUIDANCE THROUGH TAU 48, THEN ON THE HIGHER END OF 
GUIDANCE IN THE LATER TAUS, WITH MEDIUM CONFIDENCE THROUGHOUT.

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