WDPN32 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (TOKAGE) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 40.4N 152.8E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 530 NM EAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 22 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TS 11W IS CURRENTLY UNDERGOING A TRANSITION TO A STRONG SUBTROPICAL
STORM, PER AUTOMATED AND MANUAL PHASE CLASSIFICATION DATA. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED, BUT VERY
WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) WITH SHEARED
CONVECTION TO THE EAST. THE MSI REVEALS THE REMNANTS OF WEAK
FRONTAL BAND LINGERING TO THE NORTH OF THE SYSTEM AS WELL. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
EXPOSED LLCC IN THE MSI AND A QUASI-MICROWAVE EYE FEATURE IN A
250538Z SSMIS 37GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 55
KNOTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE CONGRUENCE OF
AVAILABLE AGENCY FIXES, OBJECTIVE ANALYSES AND A 250216Z AMSR2 WIND
SPEED ANALYSIS. THE SYSTEM IS MOVING RAPIDLY NORTHEASTWARD ALONG
THE NORTHWESTERN PERIPHERY OF THE DEEP SUBTROPICAL RIDGE TO THE
NORTH, ALONG THE GRADIENT OF ENHANCED WESTERLIES ASSOCIATED WITH A
200MB JET STREAK APPROACHING FROM THE WEST. THE SYSTEM IS IN THE
INTERMEDIATE SUBTROPICAL PHASE, GENERALLY CHARACTERIZED BY HAVING
FEATURES OF BOTH A TROPICAL AND EXTRATROPICAL CYCLONE. THE
ENVIRONMENT IS BECOMING INCREASINGLY HOSTILE, WITH HIGH VWS, AND
COOL SSTS BEING MARGINALLY OFFSET BY GOOD EQUATORWARD AND ENHANCED
POLEWARD OUTFLOW INTO THE RIGHT EXIT REGION OF THE JET STREAK.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T4.5 - 77 KTS
   CIMSS SATCON: 57 KTS AT 250306Z
   CIMSS ADT: 51 KTS AT 250540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 23-24 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE WEST.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 11W WILL CONTINUE TO TRACK RAPIDLY
NORTHEASTWARD THROUGH THE SHORT DURATION OF THE FORECAST PERIOD,
ALONG THE INCREASINGLY TIGHT GRADIENT BETWEEN THE STR TO THE SOUTH
AND A REMNANT FRONTAL BOUNDARY SITTING TO THE NORTH. WHILE
CURRENTLY ASSESSED AS A HYBRID TROPICAL-SUBTROPICAL SYSTEM, IT IS
EXPECTED TO QUICKLY TRANSITION TO A FULLY EXTRATROPICAL, GALE-FORCE
LOW AS IT TAKES ON INCREASINGLY LOW LEVEL TEMPERATURE ADVECTION, IS
SMOTHERED BY DRY AIR IN THE MID-LEVELS, IS SHEARED APART BY RAPIDLY
INCREASING VWS AND EMBEDS UNDER THE AFOREMENTIONED 200MB JET STREAK
AND 500MB TROUGH. 

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT THROUGH THE FORECAST PERIOD, WITH MINIMAL ALONG AND
CROSS-TRACK SPREAD IN THE CONSENSUS MEMBERS. THE JTWC FORECAST LIES
RIGHT DOWN THE MIDDLE OF THE MODEL ENVELOPE WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS IN OVERALL GOOD AGREEMENT, WITH GFS AND HWRF
BEING SLIGHTLY MORE AGGRESSIVE THAN THE DECAY-SHIPS GUIDANCE WHICH
DROPS THE SYSTEM TO JUST 20 KNOTS IN 24 HOURS. WITH THE UPPER-LEVEL
DYNAMICS CURRENTLY IN PLAY, THE JTWC FORECAST CALLS FOR SLOW
WEAKENING, AND LIES ON THE HIGHER END OF THE GUIDANCE WITH HIGH
CONFIDENCE. 

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