WDPN31 PGTW 252100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (SEPAT) WARNING 
NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.5N 140.3E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 56 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A NEARLY
FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL
DEPRESSION (TD) 02W (SEPAT). DEEP CONVECTION IS LIMITED, AS THE 
ENVIRONMENT IS BECOMING INCREASINGLY HOSTILE TOWARD TROPICAL 
DEVELOPMENT. EIR REVEALS SMALL FLARE UPS OF CONVECTION, IMMEDIATELY 
SHEARED TO THE EAST-NORTHEAST. SEA SURFACE TEMPERATURES (SST) ARE 
GETTING COOLER AS THE SYSTEM TRACKS POLEWARD AND EASTWARD AND ARE 
CURRENTLY BELOW 24 C. TD 02W IS BEGINNING TO INTERACT WITH THE 
BAROCLINIC ZONE AHEAD OF AN APPROACHING DEEP-LAYER TROUGH FROM THE 
WEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON AN 
ALMOST FULLY EXPOSED LLCC IN THE EIR IMAGERY LOOP. THE INITIAL 
INTENSITY OF 25 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE 
AGENCY DVORAK AND THE AUTOMATED FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 251730Z
   CIMSS AIDT: 38 KTS AT 251730Z
   CIMSS D-PRINT: 27 KTS AT 251820Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 23-24 CELSIUS
   OUTFLOW: WEAK RADIAL
   OTHER FACTORS: SYSTEM IS BEGINNING ITS EXTRATROPICAL TRANSITION

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 SEPAT IS CURRENTLY UNDERGOING EXTRATROPICAL
TRANSITION AS IT CROSSED THE AXIS OF A STR TO THE EAST AND ENTERED THE 
REGION OF COOLER (23-24 C) WATERS. TRACK FORECAST CALLS FOR 
ACCELERATING NORTHEASTWARD MOTION, ALONG THE NORTHWESTERN PERIPHERY OF 
THE RIDGE. TD 02W WILL MAINTAIN INTENSITY OVER THE NEXT 12 HOURS AND 
IS EXPECTED TO TRANSITION INTO A COLD CORE, BAROCLINIC SYSTEM BY THE 
END OF THE CURRENT FORECAST PERIOD.

MODEL DISCUSSION: JTWC TRACK FORECAST IS ASSESSED WITH HIGH 
CONFIDENCE, AS THE NUMERICAL TRACK MODEL GUIDANCE IS IN GOOD
AGREEMENT, WITNESSED BY A 55 NM CROSS-TRACK SPREAD AT TAU 24.
MEANWHILE, THE ALONG-TRACK SPREAD IS 135 NM INDICATING SOME
UNCERTAINTY IN REGARD TO THE RATE OF ACCELERATION. INTENSITY
FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE AS ALL MODELS INDICATE
STRENGTHENING THROUGHOUT TAU 24, HOWEVER THE RATE OF
INTENSIFICATION VARIES BETWEEN GUIDANCE. JTWC INTENSITY FORECAST IS
LAID CLOSE TO THE MULTI-MODEL CONSENSUS.

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