WDPN31 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (NARI) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.5N 142.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 547 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
OBSCURED TROPICAL CYCLONE WITH BUILDING DEEP CONVECTION POSITIONED
EAST OF THE CENTER OF THE CIRCULATION. DUAL CHANNEL OUTFLOW HAS
DEVELOPED OVER THE LAST SIX HOURS AS AN UPPER-LEVEL TROUGH TO THE
WEST HAS APPROACHED, ALLOWING FOR A POLEWARD OUTFLOW CHANNEL TO
FORM IN THE DIVERGENT REGION OF THE JET. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED
MSI AND A PARTIAL 130005Z METOP-B ASCAT IMAGE HIGHLIGHTING THE
EASTERN PERIPHERY OF TROPICAL STORM (TS) 06W. THE INITIAL INTENSITY
OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED SCATTEROMETRY DATA REVEALING THE STRONGEST WINDS IN
THE EASTERN SEMICIRCLE OF THE SYSTEM, WITH 40KTS OF WIND.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 38 KTS AT 0100Z
   CIMSS ADT: 32 KTS AT 122030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 06W WILL TRACK NORTHWARD WHILE STEERED BY A
SUBTROPICAL RIDGE TO THE EAST FOR THE NEXT 36 HOURS. BETWEEN TAU
36-48, THE SYSTEM IS ANTICIPATED TO ROUND THE CURVE OF THE RIDGE,
ENDING ON A NORTHEASTWARD TRACK FOR THE REMAINDER OF THE FORECAST
PERIOD. THE WHILE TRACKING NORTHWARD, TS 06W IS ANTICIPATED TO
TRACK INTO COOL SEA SURFACE TEMPERATURES BETWEEN TAU 24-36. A
LONGWAVE TROUGH APPROACHING FROM THE WEST WILL CAUSE TS 06W TO
BECOME BAROCLINIC, INITIATING EXTRATROPICAL TRANSITION AT TAU 36.
THE SYSTEM IS EXPECTED TO BECOME FULLY EXTRATROPICAL BY THE END OF
THE FORECAST PERIOD. TS 06W IS EXPECTED TO CONTINUE TO INTENSIFY
OVER THE NEXT 24 HOURS TO A PEAK OF 50KTS WHILE IN AN ENVIRONMENT
OF FAVORABLE UPPER-LEVEL DIVERGENCE AND WARM SEA SURFACE
TEMPERATURES. HOWEVER, THE RATE OF INTENSIFICATION WILL BE CAPPED
BY STRONG VERTICAL WIND SHEAR THAT EASES BETWEEN TAU 12-24. GRADUAL
WEAKENING IS CURRENTLY FORECAST TO OCCUR AFTER TAU 24 WHILE TS 06W
TRANSITIONS TO AN EXTRATROPICAL SYSTEM.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TS 06W WILL TRACK NORTHWARD FOR THE FIRST 24-36 HOURS OF THE
FORECAST BEFORE CURVING TO THE NORTHEAST. THE PRIMARY OUTLIER IS
GALWEM, WHICH BREAKS OFF TO THE WEST. THE ENSEMBLE GUIDANCE IS IN
TIGHT AGREEMENT AS WELL, HOWEVER THE WESTERNMOST ENSEMBLE MEMBERS
PASS OVER THE EASTERN COAST OF JAPAN, LENDING SLIGHT UNCERTAINTY TO
THE FORECAST. THE INTENSITY GUIDANCE HAS A MINIMAL SPREAD WITH PEAK
INTENSITIES BETWEEN 45-55KTS, LEADING TO HIGHER CONFIDENCE IN THE
INTENSITY FORECAST.

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