WDPN31 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (DAMREY)        
WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 37.3N 144.1E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 244 NM EAST-NORTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND JMA RADAR
IMAGERY DEPICT SPIRAL BANDING WRAPPING TIGHTLY INTO A DEFINED LOW
LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON EIR AND JMA HOURLY RADAR FIXES. A 271841Z SSMIS
91 GHZ MICROWAVE IMAGE REVEALS SLIGHT DECAY OF THE CORE CONVECTION
WITH DEEP CONVECTIVE BANDING LOCATED PRIMARILY OVER THE SOUTHERN
SEMICIRCLE. CONSEQUENTLY, THE INITIAL INTENSITY HAS BEEN DECREASED 
SLIGHTLY TO 60 KNOTS WITH MEDIUM CONFIDENCE BASED ON THE CIMSS AIDT AND 
SATCON ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE EAST AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RCTP: T3.0 - 45 KTS
   CIMSS SATCON: 56 KTS AT 271231Z
   CIMSS ADT: 39 KTS AT 271730Z
   CIMSS AIDT: 60 KTS AT 271830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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) 08W IS FORECAST TO RECURVE
AROUND THE WESTERN PERIPHERY OF THE STR OVER THE NEXT 12 HOURS. TS
08W IS FORECAST TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY TAU 24
AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC
ZONE. VERTICAL WIND SHEAR WILL INCREASE TO MODERATE LEVELS (20 KTS)
WITH COOLING SST (26 C TO 22 C) BY TAU 36 AS THE SYSTEM ACCELERATES
EASTWARD AND COMPLETES ETT, GAINING FRONTAL CHARACTERISTICS AND
TRANSITIONING INTO A STORM-FORCE, COLD-CORE LOW.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN TIGHT
AGREEMENT THROUGH THE FORECAST PERIOD LENDING HIGH CONFIDENCE TO
THE JTWC TRACK FORECAST. RELIABLE INTENSITY GUIDANCE SUPPORTS THE
JTWC INTENSITY FORECAST WITH MEDIUM CONFIDENCE AND SHOWS A STEADY
WEAKENING TREND AFTER TAU 12.

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