WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (NARI) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.1N 142.2E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 143 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 21 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS WRAPPING
INTO SHALLOWING SPIRAL CLOUD BANDS. THE DEEP CONVECTION HAS
COLLAPSED OVER THE LAST SIX HOURS DUE TO LOW SEA SURFACE
TEMPERATURES WHILE APPROACHING THE POLEWARD BOUNDARY OF THE
KUROSHIO CURRENT. WATER VAPOR IMAGERY REVEALS OUTFLOW EASTWARD AS
THE DEEP-LAYER TROUGH TO THE WEST INTRODUCES PRESSURE ON THE
WESTERN PERIPHERY OF TROPICAL STORM (TS) 06W. THE COLLAPSED
CONVECTIVE SPIRAL BANDING IS APPARENT IN A 132142Z DMSP F-16 SSMIS
91GHZ MICROWAVE IMAGE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED MSI AND A 122345Z
METOP-B ASCAT IMAGE REVEALING THE ASYMMETRIC CIRCULATION CENTER.
THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE SAME SCATTEROMETRY, WHICH REVEALS A MAXIMUM OF 45KTS
IN THE EASTERN PORTION OF THE ASYMMETRIC WIND FIELD.

INITIAL WIND RADII BASIS: 122345Z METOP-B ASCAT SCATTEROMETRY

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 48 KTS AT 132159Z
   CIMSS ADT: 37 KTS AT 132030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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: EXTRATROPICAL TRANSITION IS ANTICIPATED TO
COMMENCE BY TAU 12. A DEEP-LAYER TROUGH TO THE WEST WILL FORCE TS
06W INTO THE BAROCLINIC ZONE, RESULTING IN FRONTOGENESIS. TS 06W IS
ANTICIPATED TO COMPLETE EXTRATROPICAL TRANSITION BY TAU 24. TS 06W
HAS ASSUMED A NORTH-NORTHWESTWARD TRACK DURING THE LAST SIX HOURS.
FOR THE NEXT 12 HOURS, THE SYSTEM IS ANTICIPATED TO CURVE TOWARDS A
NORTHEASTWARD TRACK WHILE ROUNDING THE NORTHWESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE. THE NORTHEASTWARD TRACK WILL CONTINUE FOR THE
REMAINDER OF THE FORECAST PERIOD. THE SYSTEM WILL CONTINUE TO
WEAKEN TO 30KTS BY THE END OF THE FORECAST AS THE SYSTEM UNDERGOES
EXTRATROPICAL TRANSITION AND BECOMES EMBEDDED WITHIN THE
UPPER-LEVEL JET.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN STRONG
AGREEMENT THAT TS 07W WILL CURVE NORTHEASTWARD OVER THE NEXT 24
HOURS. THE CROSS-TRACK SPREAD BY THE END OF THE FORECAST PERIOD IS
55NM. ENSEMBLE MODELS ALSO ARE IN TIGHT AGREEMENT, HOWEVER THE
WESTERNMOST FEW OF THE ENSEMBLE MEMBERS OF BOTH ECENS AND GEFS SKIM
THE TOHOKU REGION OF NORTHERN JAPAN. THE INTENSITY GUIDANCE IS IN
GOOD AGREEMENT THAT CONSISTENT WEAKENING WILL OCCUR FOR THE
REMAINDER OF THE FORECAST WITH THE EXCEPTION OF HWRF, WHICH SHOWS A
SLIGHT INTENSIFICATION PERIOD IN THE FIRST 12 HOURS OF THE FORECAST
FOLLOWED BY A PERIOD OF WEAKENING.

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