WDIO32 PGTW 092100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03B (THREE)
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.3N 91.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 120 NM SOUTH OF CHITTAGONG
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CYCLONE THAT CONTINUES TO BE SHEARED FROM THE EAST, WITH A MASS OF
DEEP CONVECTION DISPLACED TO THE WEST OF A PARTIALLY EXPOSED
LOW-LEVEL CIRCULATION (LLCC). THE INTIAL POSITION IS BASED ON THE
EIR IMAGERY ALONG WITH RADAR IMAGERY. AN EARLIER 091149Z SMAP
WINDSPEED IMAGE SHOWED A SWATH OF 35-40 KNOT WINDS OVER THE
SOUTHERN SEMICIRCLE WITH WEAKER WINDS OVER THE CENTER AND NORTHWEST
SEMICIRCLE. THE INITAL INTENSITY REMAINS AT 40 KTS BASED ON A
COMBINATION OF OBJECTIVE ADT (35 KTS) AND SUBJECTIVE DVORAK
INTENSITY ESTIMATES RANGING FROM T2.0 (30 KTS) AND T2.5(35 KTS). IN
ADDITION TO THE EARLIER SMAP WINDSPEED IMAGE RANGING (35-40 KTS). THE
ENVIRONMENTAL CONDITIONS REMAIN MARGINALLY UNFAVORABLE WITH HIGH
VERTICAL WIND SHEAR (VWS) OFFSET BY WARM SEA SURFACE TEMPERATURES
(SSTS).

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T1.0 - 25 KTS
   CIMSS ADT: 35 KTS AT 091730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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: TC 03B IS FORECAST TO CONTINUE TRACKING
NORTH-NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF A LOW-LEVEL
STEERING RIDGE TO THE SOUTHEAST WITH A LOW-LEVEL INFLUENCE BY 
SOUTHWEST MONSOON FLOW. OVER THE NEXT 12 HOURS, THE SYSTEM IS EXPECTED 
TO CONTINUE THIS GENERAL POLEWARD TRACK MOTION WITHIN MARGINALLY 
UNFAVORABLE CONDITIONS WITH HIGH VWS BEFORE MAKING LANDFALL OVER THE 
SOUTHERN TIP OF BALUKHALI BAZAR, BANGLADESH. BY TAU 24, THE SYSTEM IS
EXPECTED TO BE FULLY OVER LAND WITH DISSIPATION EXPECTED TO OCCUR
SHORTLY THEREAFTER.


MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS MIXED, 
WITH THE GFS, GFS ENSEMBLE MEAN AND NAVGEM KEEPING THE SYSTEM ON THE 
WESTERN SIDE OF THE GUIDANCE ENVELOPE AND THEREFORE OVER WATER LONGER.
WHILE THE ECMWF AND THE ECMWF ENSEMBLE MEAN ARE ON THE EASTERN EDGE
OF THE GUIDANCE MAKING LANDFALL INTO MYANMAR. GIVEN THE LARGE SPREAD 
THE JTWC TRACK FOLLOWS CLOSE TO THE MULTI-MODEL CONSENSUS. THE JTWC 
INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE AND FOLLOWS THE 
MULTI-MODEL CONSENSUS WITH ALL GUIDANCE SHOWING A GRADUAL WEAKENING 
TREND THROUGH THE REMAINED OF THE FORECAST. 

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