WDPN31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (EWINIAR) WARNING NR 
020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.4N 133.0E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 279 NM EAST OF KADENA AB, OKINAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS CONTINUED

DETERIORATION DUE TO COLD LOW LEVEL DRY AIR INTRUSION, COOLING SST,
AND INCREASING VWS, AS EVIDENCED BY STRATOCUMULUS CLOUD LINES FEEDING 
TOWARD THE CENTER THAT IS OFFSET FROM THE CENTRAL CONVECTION THAT IS 
NOW ELONGATED AND SHEARED NORTHWESTWARD. THE INITIAL POSITION, 
EXTRAPOLATED FROM RADAR FIXES AND A MICROWAVE EYE IN THE 290921Z 
SSMIS 36GHZ IMAGE, IS PLACED WITH HIGH CONFIDENCE. THE INITIAL 
INTENSITY IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON OVERALL 
ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK ESTIMATES (SEE BELOW) AND 
REFLECTS THE 6-HR DETERIORATION. ANALYSIS REVEALS AN UNFAVORABLE 
ENVIRONMENT WITH COOLING SST, STRONG VWS, AND COLD LOW LEVEL DRY AIR 
INTRUSION OFFSET BY STRONG POLEWARD AND EQUATORWARD OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE. 

CURRENT STEERING MECHANISM: SOUTHWESTWARD EXTENSION OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 47 KTS AT 291130Z
   CIMSS AIDT: 40 KTS AT 291130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 EWINIAR WILL CONTINUE ITS 
ACCELERATED NORTHEASTWARD TRACK ON THE POLEWARD SIDE OF THE STEERING 
STR. THE UNFAVORABLE ENVIRONMENT WILL CONTINUE TO GRADUALLY ERODE THE 
SYSTEM. CONCURRENTLY BY TAU 36, THE SYSTEM WILL ENTER THE BAROCLINIC 
ZONE AND BEGIN EXTRA-TROPICAL TRANSITION (ETT) AND BY TAU 48, TS 01W 
WILL BE REDUCED TO A 45-KT STRONG GALE-FORCE COLD-CORE LOW WITH AN 
EXPANSIVE WIND FIELD.

MODEL DISCUSSION: NUMERICAL MODELS REMIAN IN VERY TIGHT AGREEMENT,
LENDING CONTINUED HIGH CONFIDENCE TO THE JTWC TRACK FORECAST. 
HOWEVER, GIVEN THE UNCERTAINTIES ASSOCIATED WITH ETT, THERE IS ONLY 
MEDIUM CONFIDENCE IN THE INTENSITY FORECAST. 

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