WDPN31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (SEPAT) WARNING 
NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.7N 139.8E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 96 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FLARE
OF CONVECTION BUILDING EAST OF AN EXPOSED LOW-LEVEL CIRCULATION
CENTER. AN APPROACHING TROUGH FROM THE WEST HAS CLEARLY BEGUN TO 
INFLUENCE THE TROPICAL DEPRESSION (TD), INDUCING STRONG WESTERLY
VERTICAL WIND SHEAR. THE SYSTEM IS APPROACHING THE BAROCLINIC ZONE, 
WHICH IS AN UNFAVORABLE ENVIRONMENT FOR TROPICAL CYCLONE
DEVELOPMENT. WATER VAPOR IMAGERY REVEALS THAT THE UPPER LEVEL
ENVIRONMENT IS UNFAVORABLE AS TD 02W IS CENTERED IN AN UPPER-LEVEL
DEFORMATION ZONE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED EIR. THE POSITION
IS ALSO SUPPORTED BY AN EARLIER 251105Z TROPICS-5 TMS 91GHZ
MICROWAVE IMAGE REVEALING A DEEP CONVECTIVE PLUME IN THE VICINITY
OF THE IDENTIFIED LOW-LEVEL CIRCULATION. THE INITIAL INTENSITY OF
25 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 251053Z METOP-B
ASCAT IMAGE REVEALING A SWATH OF 25KT WINDS IN THE SOUTHWESTERN
QUADRANT OF THE CIRCULATION.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A SUBTROPICAL
RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   CIMSS SATCON: 33 KTS AT 250911Z
   CIMSS ADT: 25 KTS AT 250830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: WEAK RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 02W IS APPROACHING THE BAROCLINIC ZONE AND
IS ANTICIPATED TO PASS OVER COOL WATERS (BELOW 26C) WITHIN THE NEXT
12 HOURS, INITIATING A PERIOD OF EXTRATROPICAL TRANSITION. THE
PRIMARY STEERING MECHANISM DRIVING THE SYSTEM TO THE NORTHWEST IS
THE SUBTROPICAL RIDGE TO THE EAST. AN APPROACHING DEEP-LAYER TROUGH
WILL INCREASE TRACK SPEED FOR THE REMAINDER OF THE FORECAST PERIOD.
THE SYSTEM IS FORECAST TO MAINTAIN AN INTENSITY 25KTS FOR THE NEXT
12 HOURS. TD 02W WILL INTENSIFY TO 30KTS AFTER TAU 12 DUE TO
BAROCLINIC FORCING AS THE SYSTEM BECOMES FULLY EXTRATROPICAL. 

MODEL DISCUSSION: THE DETERMINISTIC MODEL GUIDANCE IS IN STRONG
AGREEMENT THAT THE SYSTEM WILL CONTINUE ON A NORTHEASTWARD TRACK
FOR THE NEXT 24 HOURS. THE CROSS-TRACK SPREAD IS 25NM BY THE END OF
THE FORECAST PERIOD AND THE ALONG-TRACK SPREAD IS 140NM BY TAU 24.
THE INTENSITY GUIDANCE IS IN STRONG AGREEMENT AS WELL THAT THE
SYSTEM WILL REMAIN 25-30KTS FOR THE NEXT 24 HOURS.

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