WDPN33 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (NEOGURI) WARNING NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.2N 156.8E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 446 NM NORTH-NORTHEAST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
ELONGATED CONVECTIVE FIELD WITH DEEP CONVECTION REBUILDING OVER THE
CIRCULATION CENTER OF TROPICAL STORM (TS) 25W. THE UPPER-LEVEL
TROUGH TO THE NORTHWEST CONTINUES TO ENHANCE OUTFLOW STRONGLY, BUT
ALSO CAUSES STRONG SOUTHWESTERLY 20-25KT VERTICAL WIND SHEAR. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED ANIMATED EIR. THE INITIAL INTENSITY OF 60 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON 241021Z METOP-C ASCAT DATA
REVEALING A SLIGHTLY ASYMMETRIC WIND FIELD WITH ENHANCED WINDS TO
THE SOUTHEAST FO THE CIRCULATION CENTER.

INITIAL WIND RADII BASIS: 241021Z METOP-C ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT BETWEEN
TWO SUBTROPICAL RIDGES

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 49 KTS AT 240744Z
   CIMSS ADT: 51 KTS AT 241140Z
   CIMSS AIDT: 50 KTS AT 241140Z
   CIMSS D-MINT: 47 KTS AT 240813Z
   CIMSS D-PRINT: 47 KTS AT 241210Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 25W WILL GRADUALLY CURVE
TO A NORTHWESTWARD TRACK OVER THE NEXT 24 HOURS AS THE SUBTROPICAL
RIDGE TO THE WEST IS ERODED BY A DEEP-LAYER TROUGH. THE COMPETING
STEERING ENVIRONMENT WILL REMAIN DESPITE THE SLIGHT WEAKENING OF
THE RIDGE, AND THE SYSTEM WILL SHARPLY TRACK WESTWARD THROUGH TAU
36. AFTER A QUASI-STATIONARY PERIOD, A SHARP TURN TO THE NORTHWEST
WILL OCCUR AFTER TAU 48 AS THE DEEP LAYER JET ENHANCES THE TRACK
SPEED ALONG THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE
EAST. DUE TO THE COMPLEXITY OF THE STEERING ENVIRONMENT, IT IS
POSSIBLE THAT ERRATIC JAGGED OR LOOPING TRACK MOTION MAY OCCUR
BETWEEN TAUS AND IS NOT CAPTURED WITHIN THE WARNING GRAPHIC. TS 25W
WILL SLOWLY WEAKEN OVER THE NEXT 36 HOURS AS VERTICAL WIND SHEAR
DECREASES SLIGHTLY AS THE UPPER-LEVEL TROUGH CURRENTLY POSITIONED
NORTH OF THE SYSTEM MOVES EASTWARD. AT THE SAME TIME, THE SYSTEM
WILL RECURVE OVER A COOL WAKE FROM PREVIOUS UPWELLING, REMOVING THE
HEAT SOURCE. THE AFOREMENTIONED UPSTREAM TROUGH WILL REINTRODUCE
HIGH VERTICAL WIND SHEAR AT TAU 72 THAT WILL CONTINUE THROUGH THE
END OF THE FORECAST PERIOD. BAROCLINIC FORCING AS THE SYSTEM BEGINS
EXTRATROPICAL TRANSITION AT TAU 72 WILL SLIGHTLY INCREASE THE
INTENSITY, LEADING TS 25W TO BE A 60KT EXTRATROPICAL CYCLONE BY THE
END OF THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN MODERATE
AGREEMENT THAT TS 25W WILL SHARPLY TURN TO THE WEST WITHIN THE NEXT
12-24 HOURS, FOLLOWED BY ANOTHER SHARP TURN AT TAU 48. THERE ARE A
DECENT AMOUNT OF DIFFERENCES BETWEEN TRACK SPEED AND ANGLES OF THE
SHARP TRACK TURNS IN THE MODEL SOLUTIONS WHICH LEAD TO MEDIUM
CONFIDENCE IN THE NEAR-TERM FORECAST AND LOW CONFIDENCE IN THE
LONG-TERM FORECAST. THE INTENSITY GUIDANCE FOLLOWS SUIT AND
GENERALLY INDICATES WEAKENING IN THE NEAR-TERM FORECAST AND
INTENSIFICATION IN THE LATE-TERM DUE TO BAROCLINIC FORCING.
NONETHELESS, REPRESENTED VARIATIONS OF DWELL TIME OVER COOL WATER
AND TRACK SPEEDS CAN INFLUENCE THE AMOUNT OF EXPOSURE TS 25W HAS TO
WARM WATER, SO THE INTENSITY FORECAST CONFIDENCE FOLLOWS THE TRACK
CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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