WDIO32 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03B (THREE)      
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.8N 91.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 151 NM SOUTH OF CHITTAGONG
   MOVEMENT PAST 6 HOURS: EASTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY-
EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION WITH DISORGANIZED
CONVECTION FLARING OVER THE WESTERN SEMICIRCLE. HOWEVER, A 090355Z
ASCAT-B BULLSEYE IMAGE REVEALS A SYMMETRIC CIRCULATION WITH A SWATH
OF 35 TO 40 KNOT WINDS OVER THE SOUTHERN SEMICIRCLE, WHICH SUPPORTS
THE INITIAL INTENSITY ASSESSMENT OF 40 KNOTS. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI, WHICH INDICATES A
SLOW EASTWARD TRACK MOTION. ENVIRONMENTAL ANALYSIS INDICATES A
MARGINALLY UNFAVORABLE ENVIRONMENT WITH HIGH (25-30 KNOTS) EASTERLY
VERTICAL WIND SHEAR AND BROAD DIFFLUENCE FLOW ALOFT.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: LOW-LEVEL STEERING RIDGE POSITIONED TO
THE SOUTHEAST WITH FLOW ENHANCED BY THE SOUTHWEST MONSOON

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 03B IS FORECAST TO TRACK EAST-NORTHEASTWARD
TO NORTHEASTWARD ALONG THE NORTHWESTERN FLANK OF THE STEERING FLOW
THROUGH THE FORECAST PERIOD. DUE TO THE MARGINALLY UNFAVORABLE
ENVIRONMENTAL CONDITIONS, THE SYSTEM IS NOT EXPECTED TO INTENSIFY
BUT SHOULD STEADILY WEAKEN AS IT APPROACHES THE MYANMAR COAST WITH
DISSIPATION OCCURRING WITHIN THE NEXT 24 TO 36 HOURS.

MODEL DISCUSSION: DUE TO THE RAPID FORMATION OF THE WEAK SYSTEM,
NUMERICAL MODEL GUIDANCE IS SEVERELY LIMITED WITH THE MESOSCALE
MODELS (HWRF, COTC AND CTCX) TRACKING THE SYSTEM EAST-NORTHEASTWARD
TO NORTHEASTWARD. THE 090000Z GFS ENSEMBLE (GEFS) SHOWS THE BULK OF
SOLUTIONS TRACKING THE SYSTEM INTO MYANMAR WITH NO SIGNIFICANT
DEVELOPMENT. THE 081800Z ECMWF ENSEMBLE (EPS) IS MORE LIMITED WITH
A SPARSE SET OF SOLUTIONS TRACKING THE WEAK SYSTEM NORTHEASTWARD TO
NORTH-NORTHEASTWARD. DUE TO THE LACK OF GUIDANCE, THE CONFIDENCE IN
BOTH THE JTWC TRACK AND INTENSITY FORECAST IS MEDIUM.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
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