WDPN31 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (BAVI) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.7N 159.0E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 834 NM EAST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A STEADILY
CONSOLIDATING VORTEX WITH PERSISTENT CONVECTIVE BANDING WRAPPING
INTO THE CORE, ESPECIALLY ON THE WESTERN FLANK. ANIMATED WATER
VAPOR IMAGERY REVEALS ROBUST POLEWARD OUTFLOW ALOFT AIDED BY A TUTT
CELL TO THE NORTHEAST OF 09W, IN ADDITION TO GOOD EQUATORWARD
OUTFLOW THAT HAS IMPROVED OVER THE PAST 6 HOURS. A 020305Z AMSR-2
89 GHZ MICROWAVE IMAGE CONFIRMS THE IMPROVING CONSOLIDATION OF
CONVECTION AROUND THE CORE IN ALL BUT THE NORTHEASTER QUADRANT. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
ANIMATED MSI AND EXTRAPOLATION FROM THE AMSR-2 MICROWAVE IMAGERY. A
020127Z OCEANSAT-3 OSCAT IMAGE SHOWS ASYMMETRY IN THE WIND FIELD
AROUND THE VORTEX, WITH THE STRONGEST WINDS IN THE NORTHERN
SEMICIRCLE. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE OSCAT IMAGE AND THE SPREAD OF AGENCY DVORAK
FIXES, BALANCED BY THE SLIGHTLY LOWER CIMSS OBJECTIVE INTENSITY
ESTIMATES. THE ENVIRONMENT IS CHARACTERIZED AS HIGHLY FAVORABLE
WITH VERY WARM SEA SURFACE TEMPERATURES, HIGH OCEAN HEAT CONTENT,
AND STRONG OUTFLOW ALOFT. THE ONLY LIMITING ENVIRONMENTAL FACTOR IN
THE SHORT TERM IS MODERATE VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T1.5 - 25 KTS
   PHFO: T1.5 - 25 KTS
   CIMSS SATCON: 49 KTS AT 020400Z
   CIMSS ADT: 55 KTS AT 020550Z
   CIMSS AIDT: 47 KTS AT 020550Z
   CIMSS D-MINT: 37 KTS AT 020253Z
   CIMSS D-PRINT: 41 KTS AT 020550Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: 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 EAST. THE
SYSTEM IS EXPECTED TO ASSUME A WESTWARD TRAJECTORY THROUGH TAU 60
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 60 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 JUST SOUTH OF TINIAN AROUND 052200Z.
INTENSIFICATION IN THE NEXT 12 HOURS IS EXPECTED TO BE SLOW BUT
STEADY BEFORE THE EASTERLY VWS REDUCES AND AS THE SYSTEM CONTINUES
TO CONSOLIDATE. 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 AFTER TAU 72 AND CONTINUING THROUGH PASSAGE TROUGH THE
NORTHERN MARIANAS, RESULTING IN THE INTENSITY LEVELING OFF AT A
PEAK OF 135 KTS FROM TAU 72 THROUGH THE REMAINDER OF THE FORECAST
PERIOD. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE CONTINUES TO HAVE A MODEST
SPREAD, WITH A CROSS-TRACK SPREAD OF 140 NM AT TAU 72 INCREASING TO
180 NM AT TAU 120. ALL CONSENSUS MEMBERS LIE ON A TRACK ENVELOPE
THAT PASSES WITHIN ABOUT 70 NM TO THE NORTH AND SOUTH OF TINIAN
WITH ONLY A FEW OUTLIERS. THE JTWC TRACK FORECAST IS PLACED CLOSE
TO THE MULTI-MODEL CONSENSUS 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
(EXCLUDING DECAY SHIPS) 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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