WDPN31 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (TWENTYFIVE) 
WARNING 
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.8N 139.2E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 295 NM NORTH OF ULITHI
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
FORMATIVE BANDING WITH LARGE POCKETS OF DEEP SUSTAINED CONVECTION
TO THE WEST AND NORTHEAST OF THE CIRCULATION CENTER. THE INITIAL 
POSITION IS PLACED WITH LOW CONFIDENCE BASED UPON MULTIPLE AGENCY 
FIXES AND EXTRAPOLATION OF A 241642Z ATMS 165GHZ MICROWAVE IMAGE. 
THE INITIAL INTENSITY IS HEDGED SLIGHTLY HIGHER THAN MULTIPLE AGENCY 
DVORAK ESTIMATES AND SLIGHTLY LOWER THAN THE ADVANCED DVORAK 
TECHNIQUE. ENVIROMENTAL CONDITIONS REMAIN FAVORABLE WITH MODERATE 
POLEWARD AND EQUATORWARD OUTFLOW, LOW VERTICAL WIND SHEAR, AND WARM 
(29-30C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: WIND RADII HEDGED SLIGHTLY LARGER THAN 
OBJECTIVE BEST TRACK IN NORTHEAST QUADRANT BASED ON 241230Z PARTIAL 
ASCAT-C PASS.

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF BUILDING
SUBTROPICAL RIDGE POSITIONED TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 38 KTS AT 241840Z
   CIMSS ADT: 39 KTS AT 241910Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM 25W WILL CONTINUE TO TRACK
NORTH-NORTHWESTWARD OVER THE NEXT 36-48 HOURS AS IT REMAINS UNDER
THE INFLUENCE OF THE SUBTROPICAL RIDGE TO THE EAST-NORTHEAST.
SHORTLY AFTER TAU 48, THE SYSTEM IS EXPECTED TO BEGIN ROUNDING THE
SUBTROPICAL RIDGE AXIS WHERE IT WILL MAKE A TURN TO THE
NORTH-NORTHEAST AND INCREASE TO TYPHOON STRENGTH. BY TAU 72 TS 25W
WILL REMAIN IN A FAVORABLE ENVIRONMENT CONTINUING TO INTENSIFY TO A
PEAK INTENSITY OF 80 KTS. THEREAFTER, THE SYSTEM WILL BEGIN
ENCOUNTERING COOLING SEA SURFACE TEMPERATURES, INCREASED VERTICAL
WIND SHEAR AS IT MOVES THROUGH THE MID-LATITUDE WESTERLIES, AND
BEGINS TO TRANSITION TO AN EXTRATROPICAL LOW PRESSURE SYSTEM.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT IN
REGARDS TO THE FORECAST TRACK FOR TS 25W, WITH ALMOST ALL MODELS
SHOWING A GENERALLY NORTH-NORTHWESTWARD TRACK FOLLOWED BY A RECURVE
TO THE NORTHEAST BETWEEN TAUS 48 AND 72. NVGM IS STILL THE MAJOR
OUTLIER OF THE MULTIPLE MODEL CONSENSUS. EXCLUDING NVGM,
CROSS-TRACK MODEL SPREAD IS LESS THAN 150 NM ALL THE WAY UP TO TAU
96. NUMERICAL MODEL GUIDANCE IS IN MODERATE AGREEMENT IN REGARDS TO
THE INTENSITY FORECAST, WITH MOST MODELS SHOWING STEADY
INTENSIFICATION LEADING TO A PEAK INTENSITY FROM TAU 72 TO TAU 96.
THEREAFTER, A WEAKENING TREND IS EXPECTED THROUGH THE REMAINDER OF
THE FORECAST. THE MODELS CURRENTLY DO NOT AGREE ON THE PEAK
INTENSITY WITH DSHN PEAKING AT 95 KTS AND COTI PEAKING AT 55 KTS,
WITH MOST OTHERS AROUND 70-85 KTS. TO OFFSET DSHN, THE FORECAST
INTENSITY IS PLACED SLIGHTLY LOWER THAN CONSENSUS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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