WDPN31 PGTW 261500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (DAMREY) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.0N 151.1E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 728 NM SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 25 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS AN
ELONGATED SYSTEM THAT HAS MOSTLY MAINTAINED ITS OVERALL CONVECTIVE 
STRUCTURE AS IT CONTINUED TO ACCELERATE NORTHWESTWARD. THE INITIAL 
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTLY OBSCURED 
BUT DEFINED LOW LEVEL CIRCULATION (LLC) IN THE 261126Z AMSU-B 
MICROWAVE IMAGE. THE INITIAL INTENSITY OF 50KTS IS ALSO ASSESSED WITH 
HIGH CONFIDENCE BASED ON EXTRAPOLATION FROM THE 260719Z SMAP IMAGE 
THAT SHOWED AN AVERAGE OF 50KTS AROUND THE LLC, AND IS SUPPORTED BY 
THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE
SUSTAINED CONVECTIVE STRUCTURE. ANALYSIS INDICATES A MARGINALLY
FAVORABLE ENVIRONMENT WITH WARM SST, LOW VWS, AND STRONG VENTILATION 
ALOFT.

INITIAL WIND RADII BASIS: SMAP DATA.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 45 KTS AT 261130Z
   CIMSS D-PRINT: 47 KTS AT 261200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS DAMREY WILL CONTINUE ON A FAST TRACK
NORTH-NORTHWESTWARD UNDER THE STR. AFTER TAU 24, A MID-LATITUDE
TROUGH TRANSITING FROM THE NORTHWEST WILL WEAKEN THE STR AND ALLOW
THE SYSTEM TO TRACK MORE NORTHWARD THEN ACCELERATE NORTHEASTWARD
AFTER TAU 36. THE MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A
MODEST INTENSIFICATION TO A PEAK OF 65KTS BY TAU 36 AS IT CRESTS
THE STR AXIS. AFTERWARD, INCREASING VWS AND COOLING SST WILL BEGIN
TO ERODE THE SYSTEM. CONCURRENTLY BY TAU 36, TS 08W WILL ENTER THE
COLD BAROCLINIC ZONE AND BEGIN EXTRA-TROPICAL TRANSITION AND, BY TAU 
72, WILL TRANSFORM INTO A COLD-CORE LOW WITH EXPANDING GALE-FORCE
WINDS. 


MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT UP
TO TAU 48 THEN WITH GRADUAL AND EVEN SPREAD TO 360NM BY TAU 72,
LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.


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