WDPN31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (FIFTEEN) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.1N 160.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 365 NM WEST-NORTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: EASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS DEEPENED AND BECOME MORE CONSOLIDATED AS POLEWARD OUTFLOW INTO A
TUTT CELL TO THE NORTH HAS IMPROVED. THE INITIAL POSITION AND 
INTENSITY ARE PLACED WITH HIGH CONFIDENCE BASED 111006OZ ASCAT 
BULLSEYE PASS. THE INITIAL INTENSITY OF 35KTS IS ALSO SUPPORTED BY THE 
PGTW AND ADT DVORAK ESTIMATES. THE ENVIRONMENT IS FAVORABLE WITH 
STRONG POLEWARD OUTFLOW, AND WARM SST SLIGHTLY OFFSET BY LIGHT TO 
MODERATE VERTICAL WIND SHEAR.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A
NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTHEAST.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 35 KTS AT 110810Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 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: 15W WILL CONTINUE ON ITS CURRENT TRACK UNDER
THE STEERING INFLUENCE OF THE NER. AFTER TAU 36, THE LOW- TO
MID-LAYER OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST WILL
ASSUME STEERING AND DRIVE THE CYCLONE MORE POLEWARD. AFTER TAU 72,
TD 15W WILL CREST THE STR AXIS AND ACCELERATE NORTHEASTWARD. THE
FAVORABLE CONDITIONS WILL FUEL A STEADY INTENSIFICATION TO A PEAK
OF 80KTS BY TAU 48. AFTER TAU 48, INCREASING VWS AND COOLING SST
WILL BEGIN TO ERODE THE SYSTEM. CONCURRENTLY BY TAU 48, IT WILL
BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT APPROACHES THE
BAROCLINIC ZONE. BY TAU 96, 15W WILL COMPLETE ETT AND TRANSFORM
INTO A 70KT COLD-CORE LOW WITH AN EXPANSIVE WIND FIELD. 


MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT,
LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. THERE IS MEDIUM
CONFIDENCE IN THE INTENSITY FORECAST. 

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