WDPN31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (DAMREY) WARNING NR 
018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.5N 147.6E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 456 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 27 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MEDIUM SIZED
SYSTEM THAT HAS SLIGHTLY IMPROVED WITH DEEPENED CENTRAL
CONVECTION OVER THE LAST SIX HOUR AS IT CONTINUED TO ACCELERATE
NORTHWESTWARD. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A DIMPLE NEAR THE CENTER, AN INDICATION OF A
FORMATIVE EYE. THE INITIAL INTENSITY OF 60KTS IS ALSO ASSESSED WITH
HIGH CONFIDENCE BASED ON THE HIGH END OF AGENCY AND AUTOMATED
DVORAK ESTIMATES AND IS CONSISTENT WITH A FORMATIVE EYE. ANALYSIS
INDICATES A FAVORABLE ENVIRONMENT WITH WARM SST, LOW VWS, AND
STRONG VENTILATION ALOFT.

INITIAL WIND RADII BASIS: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   SATCON: 54 KTS AT 270500Z
   CIMSS AIDT: 58 KTS AT 270530Z
   CIMSS D-PRINT: 58 KTS AT 270500Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: TS DAMREY WILL CONTINUE ON A FAST TRACK
NORTHWESTWARD UNDER THE STR. AFTER TAU 12, A MID-LATITUDE TROUGH
TRANSITING FROM THE NORTHWEST WILL WEAKEN THE STR AND ALLOW THE
SYSTEM TO TRACK MORE NORTHWARD THEN ACCELERATE NORTHEASTWARD. THE
FAVORABLE ENVIRONMENT WILL FUEL A MODEST INTENSIFICATION TO A PEAK OF 
65KTS BY TAU 12 AS IT CRESTS THE STR AXIS. AFTERWARD, INCREASING VWS 
AND COOLING SST WILL BEGIN TO ERODE THE SYSTEM. CONCURRENTLY BY TAU 
24, TS 08W WILL ENTER THE COLD BAROCLINIC ZONE AND BEGIN EXTRA-
TROPICAL TRANSITION AND, BY TAU 36, WILL TRANSFORM INTO A COLD-CORE 
LOW WITH EXPANDING STORM-FORCE WINDS. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT WITH
GRADUAL AND EVEN SPREAD TO JUST 129NM BY TAU 36, LENDING HIGH
CONFIDENCE TO THE JTWC TRACK FORECAST.


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