WDPN33 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 29.7N 141.2E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 165 NM NORTH-NORTHWEST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 27 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BANDING
EYE WITH STRONG POLEWARD AND EQUATORWARD OUTFLOW. A SLOT OF DRY AIR
ATTEMPTS TO WRAP INTO THE LOW-LEVEL CIRCULATION CENTER (LLCC) FROM
THE SOUTHWEST. A 142034Z RCM-3 SYNTHETIC APERTURE RADAR (SAR) IMAGE
REVEALS AN EYE FEATURE WITH A STRONG BAND OF 80-85KT WINDS WRAPPING
FROM THE EASTERN EDGE AROUND TO THE WESTERN SIDE OF THE SYSTEM. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED MSI AND SUPPORTED BY EXTRAPOLATION FROM THE SAR
IMAGE.  THE INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED SAR IMAGERY ALONG WITH THE
AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: SAR DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 49 KTS AT 0030Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TYPHOON (TY) 08W IS NOW FORECAST TO
UNDERGO A PERIOD OF RAPID INTENSIFICATION (RI) DURING THE FIRST 24
HOURS OF THE FORECAST TO A PEAK OF 115KTS WHICH WAS NOT REFLECTED
IN THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 08W IS FORECAST TO TRACK NORTHWARD THROUGH
THE FIRST 24 HOURS OF THE FORECAST PERIOD BEFORE ROUNDING THE
WESTERN PERIPHERY OF THE STR TO THE EAST FROM TAU 36-48. AFTER
ROUNDING THE RIDGE, TY 08W WILL TRACK DUE EAST-NORTHEAST THROUGH
THE REMAINDER OF THE FORECAST. RAPID INTENSIFICATION IS FORECAST TO OCCUR 
TO A PEAK OF 115KTS BY TAU 24 AND MAY REACH A HIGHER PEAK BETWEEN
TAU 24-36 THAT IS NOT REFLECTED IN THE FORECAST WARNING. AFTER TAU 36,
TY 08W WILL BECOME INFLUENCED BY MODERATE VERTICAL WIND SHEAR AND
A BRIEF PERIOD OF NEGATIVE UPPER-LEVEL CONVERGENCE WHICH WILL
INITIATE WEAKENING. DESPITE THE UPPER-LEVEL ENVIRONMENT IMPROVING
BY TAU 48, VERTICAL WIND SHEAR WILL BECOME HIGHLY UNFAVORABLE
BETWEEN TAU 48-60 AS THE SYSTEM TRACKS INTO UNFAVORABLE SEA SURFACE
TEMPERATURES THAT ARE BELOW 26 DEGREES. THE COOLER SEA SURFACE
TEMPERATURES AND BAROCLINIC ENVIRONMENT WILL INITIATE EXTRATROPICAL
TRANSITION BETWEEN TAU 60-72, WHICH WILL LEAD TO TY 08W BECOMING
FULLY EXTRATROPICAL BY TAU 96.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT THROUGH TAU 48 WITH A MINIMUM CROSS-TRACK SPREAD OF 65NM,
BUT THE ALONG-TRACK SPREAD OPENS TO 300NM BY TAU 96, WHICH LOWERS
THE UNCERTAINTY IN THE TRACK FORECAST AFTER THE SYSTEM ROUNDS THE
CURVE OF THE STR TO THE EAST. THE GEFS AND ECENS ENSEMBLE GUIDANCE
DEPICTS SOLUTIONS FARTHER WEST AND CLOSER TO THE BOSO PENINSULA
THAN CONVEYED IN THE MULTI-MODEL CONSENSUS. THE JTWC INTENSITY
GUIDANCE STRONGLY INDICATES HIGHER PROBABILITY OF RAPID
INTENSIFICATION WITHIN THE FIRST 24 HOURS OF THE FORECAST
PARTICULARLY DUE TO THE ELEVATED SEA SURFACE TEMPERATURES BETWEEN
30-31C, STRONG UPPER-LEVEL DIVERGENCE, AND LOW VERTICAL WIND SHEAR.
THE JTWC INTENSITY FORECAST LIES ABOVE THE MULTI-MODEL CONSENSUS,
WHICH IS DRAWN LOWER DUE TO GFS, HAFS-A, AND COAMPS-TC.

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