WDPN33 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.5N 140.8E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 177 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD
30-35NM EYE FEATURE WITH APPARENT SHEAR FROM THE NORTH-NORTHEAST
DEGRADING THE CONVECTIVE BANDING ON THE NORTHERN PERIMETER OF THE
TYPHOON. WATER VAPOR IMAGERY DEPICTS STRONG POLEWARD AND
EQUATORWARD OUTFLOW ENCOURAGED BY AN UPPER-LEVEL LOW TO THE NORTH
AND TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE
SOUTHEAST. THE WIND RADII ARE DISPLACED FARTHER THAN TYPICALLY
EXPECTED FROM CENTER DUE TO THE BROAD EYE DIAMETER. A 151640Z GCOM
W1 AMSR2 COLOR-ENHANCED 37GHZ IMAGE DEPICTS A LARGE CYAN RING
ENCIRCLING MICROWAVE EYE, WHICH HAS BEEN HISTORICALLY INDICATIVE OF
FUTURE RAPID INTENSIFICATION. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE AFOREMENTIONED EIR. THE INITIAL
INTENSITY OF 100 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 104 KTS AT 1800Z
   CIMSS ADT: 99 KTS AT 1900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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: TYPHOON (TY) 08W IS FORECAST TRACK
NORTH-NORTHEASTWARD AS IT BEGINS TO ROUND THE NORTHWESTERN
PERIPHERY OF THE STR TO THE SOUTHEAST. THE RIDGE MAY BECOME
MODIFIED AND FORCED SOUTHWEST AS THE LARGE TROPICAL SYSTEM DRIVES
NORTHEAST IN TO AND AROUND THE NORTHWESTERN PERIPHERY OF THE RIDGE
THROUGH TAU 36-72. TY 08W WILL CONTINUE TO INTENSIFY TO A PEAK OF
110KTS IN THE NEXT 12 HOURS AS THE TYPHOON BEGINS TO PASS SOUTHEAST
OF THE BOSO PENINSULA WHILE IN A REGION WITH HIGH SEA SURFACE
TEMPERATURES (30-31C), LOW VERTICAL WIND SHEAR, AND STRONG
UPPER-LEVEL DIVERGENCE. BETWEEN TAU 12-36, WEAKENING WILL BE
INITIATED AS THE SYSTEM APPROACHES AN UPPER-LEVEL JET, WHICH WILL
INCREASE THE VERTICAL WIND SHEAR MODERATELY TO 15-20KTS. THE
UNFAVORABLE ENVIRONMENT WILL COMPOUND AFTER TAU 48 AS THE SYSTEM
ENTERS COOL SEA SURFACE TEMPERATURES BELOW 26C AND VERTICAL WIND
SHEAR WILL RISE TO 20-25KTS. DURING THIS TIME, THE SYSTEM WILL
BEGIN EXTRATROPICAL TRANSITION BECOMING BOTH FRONTAL AND FULLY
BAROCLINIC BY THE END OF THE FORECAST PERIOD. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN EXTREMELY
STRONG CROSS-TRACK AND ALONG-TRACK AGREEMENT THROUGH TAU 48, WITH A
MAXIMUM CROSS-TRACK A SPREAD OF 150NM. BY TAU 72, THE ALONG-TRACK
SPREAD OPENS SLIGHTLY TO 200NM, WHICH IS LIKELY RELATED TO HOW
SHALLOW THE SYSTEM BECOMES AND HOW QUICKLY THE SYSTEM UNDERGOES
EXTRATROPICAL TRANSITION. THE JTWC FORECAST TRACK LIES ALONG THE
NORTHWESTERN AND NORTHERN EDGE OF THE MULTI-MODEL CONSENSUS BASED
ON ANALYSIS OF THE GEFS AND ECENS ENSEMBLES, WHICH BOTH HAVE
SOLUTIONS THAT TIGHTLY TRACK SLIGHTLY NORTHWEST OF THE JTWC
CONSENSUS AND CLOSER TO THE BOSO PENINSULA. THE JTWC INTENSITY
GUIDANCE DIFFERS GREATLY FROM THE LAST INTERPOLATED GUIDANCE, WHICH
DEPICTED A PEAK OF 115KTS, BUT NOW THE INTERPOLATED MULTI-MODEL
INTENSITY CONSENSUS DEPICTS STAGNATION FOR THE FIRST 12 HOURS OF
THE FORECAST AND CONSISTENT WEAKENING AFTER TAU 24. ANALYSIS OF THE
RAW GFS, HAFS-A, AND HWRF MODELS SHOW CONTINUED INTENSIFICATION
POSSIBLE WITHIN THE FIRST 12 HOURS DUE TO THE PREVIOUSLY MENTIONED
FAVORABLE ENVIRONMENT, THUS THE JTWC INTENSITY FORECAST IS ABOVE
CONSENSUS FOR THE FIRST 12 HOURS OF THE FORECAST AND CONTINUOUSLY
WEAKENS MIRRORING THE CONSENSUS AFTER TAU 24.

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