WDPN31 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (SEPAT) WARNING 
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.0N 139.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 198 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A NAKED LOW
LEVEL CIRCULATION CENTER (LLCC), SLOWLY DRIFTING NORTHWARD TOWARDS
HACHIJOJIMA ISLAND. THE SYSTEM IS CURRENTLY DEVOID OF SIGNIFICANT
CONVECTIVE ACTIVITY DUE TO THE PRESENCE OF DRY MID-LEVEL AIR OVER
TOP OF THE LOWER-LEVEL CIRCULATION. THE MOST ACTIVE AREA IN TERMS
OF CONVECTIVE ACTIVITY IS THE EASTERN EDGE OF THE INNERMOST RAIN
BANDS. A 242335Z ASCAT-B BULLSEYE PASS REVEALS WINDS OF 20-25 KNOTS
ACROSS MOST OF THE WESTERN HALF OF THE SYSTEM, WITH 25-30 KNOT
WINDS IN THE EASTERN HEMISPHERE, ROUGHLY FROM NNE TO SE OF THE
LLCC. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE FULLY EXPOSED LLCC IN THE MSI. THE INITIAL INTENSITY IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE OBJECTIVE AND SUBJECTIVE
INTENSITY ESTIMATES ABOVE, SUPPORTED BY THE ASCAT-B ANALYSIS.
ENVIRONMENTAL CONDITIONS CONTINUE TO DETERIORATE WITH INCREASING
NORTHWESTERLY SHEAR, DECREASING SSTS (NOW APPROACHING THE 26C
ISOTHERM), DRY MID-LEVEL AIR AND A LACK OF UPPER-LEVEL OUTFLOW DUE
TO THE SYSTEM RESIDING UNDER A COL-REGION ALOFT.

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

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   CIMSS SATCON: 35 KTS AT 242157Z
   CIMSS ADT: 25 KTS AT 250000Z
   CIMSS AIDT: 36 KTS AT 240000Z
   CIMSS D-MINT: 28 KTS AT 242057Z
   CIMSS D-PRINT: 26 KTS AT 250020Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK WESTWARD
   OTHER FACTORS: DRY MID-LEVEL AIR.

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: TROPICAL DEPRESSION (TD) 02W (SEPAT) CONTINUES
TO SLOWLY WEAKEN AS IT MOVES NORTHWARD UNDER UNFAVORABLE
ENVIRONMENTAL CONDITIONS. THE SYSTEM IS SITTING AT OR NEAR THE STR
RIDGE AXIS, SLOWING SIGNIFICANTLY AND EXHIBITING A BIT OF A WOBBLE.
TD 02W SHOULD MOVE PAST THE RIDGE AXIS OVER THE NEXT SIX HOURS AND
THEN ACCELERATE NORTHEASTWARD THROUGH THE REMAINDER OF THE
FORECAST. THE CENTER OF TD 02W IS EXPECTED TO PASS CLOSE TO THE
EASTERN COAST OF THE BOSO PENINSULA BUT SHOULD REMAIN OFFSHORE. NO
SIGNIFICANT CHANGE IS EXPECTED OVER THE COURSE OF THE NEXT 12 TO 24
HOURS IN TERMS OF THE OVERALL ENVIRONMENT. HENCE, THE SYSTEM IS
EXPECTED TO CONTINUE ITS SLOW WEAKENING TREND AS IT TRAVERSES
NORTHEASTWARD. THE SYSTEM IS EXPECTED TO BEGIN EXTRATROPICAL
TRANSITION (ETT) AS IT PASSES THE BOSO PENINSULA AND COMPLETE ETT
BY TAU 36 AS IT PASSES SOUTHEAST OF HOKKAIDO. 

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
STRONG AGREEMENT THROUGH THE BULK OF THE SHORT FORECAST PERIOD,
WITH SOME MINOR ALONG-TRACK SPREAD DEVELOPING AFTER TAU 24 AS THE
SYSTEM RACES OFF TO THE NORTHEAST. THE JTWC FORECAST IS POSITIONED
CLOSE TO THE MULTI-MODEL CONSENSUS MEAN WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS MIXED, WITH THE DECAY SHIPS (GFS AND
NAVGEM), THE HAFS-A AND THE GFS DEPICTING A SLIGHT INTENSIFICATION
OVER THE NEXT 24 HOURS, WHILE THE REMAINDER OF THE PACKAGE DEPICTS
SLOW WEAKENING TO 25 KNOTS AND THEN MAINTAINING INTENSITY THROUGH
ETT. THE JTWC FORECAST IS PLACED NEAR THE HWRF SOLUTION WITH MEDIUM
CONFIDENCE. 

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