WDPN33 PGTW 151500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.5N 140.8E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 235 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
08W (AMPIL) WITH A LARGE SYMMETRICAL EYE THAT HAS BECOME MORE
WELL-DEFINED OVER THE PAST 6 HOURS. ADDITIONALLY, THE CENTRAL DENSE
OVERCAST (CDO) HAS BECOME EVEN MORE UNIFORM AS THE TYPHOON HAS
CONTINUED INTENSIFYING, WITH NEARLY AN ANNULAR APPEARANCE NOW.
ENVIRONMENTAL CONDITIONS REMAIN HIGHLY FAVORABLE FOR FURTHER
INTENSIFICATION CHARACTERIZED BY STRONG RADIAL OUTFLOW ALOFT, VERY
LOW VERTICAL WIND SHEAR, AND WARM (30-31 C) SEA SURFACE
TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE ANIMATED EIR IMAGERY AND THE PRESENCE OF THE EYE. THE
INITIAL INTENSITY OF 95 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED
BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.5 - 102 KTS 
   CIMSS DPRINT: 90 KTS AT 151200Z 

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 08W IS FORECAST TO CONTINUE TRACKING NORTHWARD
ALONG THE WESTERN PERIPHERY OF THE STR OVER THE NEXT 12 HOURS.
AROUND TAU 24, THE SYSTEM IS FORECAST TO TURN NORTHEASTWARD ABOUT
80 NM SOUTHEAST OF YOKOSUKA AS IT ROUNDS THE STR AND PASSES BY THE
BOSO PENINSULA. AFTER TAU 24, 08W IS EXPECTED TO CONTINUE TRACKING
ALONG THE NORTHWESTERN AND THEN NORTHERN PERIPHERIES OF THE STR
THROUGH THE REMAINDER OF THE FORECAST PERIOD AS IT MAKES ITS WAY
INTO THE BAROCLINIC ZONE. EXTRATROPICAL TRANSITION IS FORECAST TO 
START AROUND TAU 72 WITH COMPLETION BY TAU 96. REGARDING THE 
INTENSITY FORECAST, 08W IS FORECAST TO CONTINUE INTENSIFYING THROUGH 
TAU 24 WITH A PEAK INTENSITY OF 115 KTS IN RESPONSE TO THE HIGHLY 
CONDUCIVE ENVIRONMENT. AFTER TAU 24, VERTICAL WIND SHEAR IS EXPECTED 
TO INCREASE TO AROUND 15-20 KTS AND SEA SURFACE TEMPERATURES ARE 
EXPECTED TO QUICKLY DROP. THIS WILL INITIATE THE WEAKENING TREND, 
WHICH WILL PERSIST THROUGH THE REMAINDER OF THE FORECAST PERIOD. 
AROUND TAU 72, SEA SURFACE TEMPERATURES WILL DROP BELOW 25 C AND 
VERTICAL WIND SHEAR WILL RISE TO OVER 25 KTS. AN INTENSITY OF 45 KTS 
IS FORECASTED AS EXTRATROPICAL TRANSITION COMPLETES NEAR THE TAU 96 
MARK. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE CONTINUES TO BE IN VERY
GOOD AGREEMENT WITH A CROSS-TRACK SPREAD OF JUST 25 NM AT TAU 24 AS
IT PASSES BY THE BOSO PENINSULA. GEFS AND ECENS MEMBERS ARE VERY
CLOSE TO THEIR ENSEMBLE MEANS AS WELL. THIS LENDS HIGH CONFIDENCE
TO THE JTWC TRACK FORECAST THOUGH TAU 72, AND MEDIUM THEREAFTER.
INTENSITY GUIDANCE IS IN SLIGHTLY WORSE AGREEMENT. MANY RAPID
INTENSIFICATION (RI) AIDS CONTINUE TO TRIGGER AND DEPICT A PEAK
INTENSITY RANGING FROM 120-130 KTS. NON-RI AIDS ARE SLIGHTLY SPLIT,
WITH HAFS-A AND HWRF BOTH DEPICTING A PEAK INTENSITY OF AROUND 105
KTS BETWEEN TAU 12 AND 24 WHILE THE STATISTICAL DYNAMICAL MODELS
AND COAMPS-TC SHOW A STEADY INTENSITY OF 95 KTS THROUGH TAU 24
BEFORE WEAKENING. ALL GUIDANCE AGREES ON WEAKENING AFTER TAU 24
THOUGH. THE JTWC INTENSITY FORECAST IS PLACED JUST BELOW THE RI
RANGE THROUGH TAU 24 AND CLOSE TO CONSENSUS AFTERWARDS WITH OVERALL 
MEDIUM CONFIDENCE. 

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