WDPN33 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.5N 140.8E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 121 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 MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE EYE
WITH A DIAMETER OF 35NM ENCIRCLED BY TIGHT BANDING WRAPPING INWARD
TO CENTER. TYPHOON 08W HAS OVERCOME THE NORTHERLY SHEAR WHICH HAS
DROPPED TO 5-10KTS. WATER VAPOR IMAGERY DEPICTS STRONG POLEWARD AND
EQUATORWARD OUTFLOW SUPPORTED BY AN UPPER-LEVEL JET TO THE NORTH
AND A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE
SOUTHEAST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON ANIMATED MSI MENTIONED ABOVE. THE INITIAL INTENSITY IS
ASSESSED WITH HIGH CONFIDENCE BASED ON A 152039Z SYNTHETIC APERTURE
RADAR (SAR) IMAGE DEPICTING A STRONG BAND OF 100-105KT WINDS
ENCIRCLING THE CORE COMBINED WITH THE AGENCY AND OBJECTIVE FIXES
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: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T6.0 - 115 KTS
   CIMSS SATCON: 98 KTS AT 0100Z
   CIMSS ADT: 104 KTS AT 0100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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: TY 08W WILL TRACK NORTHEASTWARD AS IT
CONTINUES TO ROUND THE RIDGE OF THE STR, ULTIMATELY TRACKING
WEST-NORTHWESTWARD BY THE END OF THE FORECAST PERIOD. FOR THE FIRST
12 HOURS, THE SYSTEM INTENSITY WILL STAGNATE WHILE IN A MARGINALLY
FAVORABLE ENVIRONMENT WITH MODERATE 10-15KT VERTICAL WIND SHEAR.
WEAKENING WILL BE INITIATED BY TAU 24 WHEN VERTICAL WIND SHEAR
BECOMES UNFAVORABLE ABOVE 20KTS AND THE UPPER-LEVEL ENVIRONMENT IS
NO LONGER DIVERGENT DUE TO INTERACTION WITH THE UPPER-LEVEL JET TO
THE NORTH. THE WEAKENING TREND WILL CONTINUE THROUGH THE END OF THE
FORECAST AS TY 08W PASSES OVER COOL SEA SURFACE TEMPERATURES BELOW
26C AT TAU 36. BY TAU 48, THE SYSTEM BECOMES EMBEDDED UNDER THE JET
WHICH ENHANCES THE RATE OF EXTRATROPICAL TRANSITION AS THE SYSTEM
BECOMES SHALLOW, BAROCLINIC, AND FRONTAL.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TY 08W WILL CONTINUE TO TRACK OVERALL EAST-NORTHEASTWARD UNDER
THE STEERING INFLUENCE OF THE STR TO THE EAST. THE JTWC TRACK LIES
JUST WEST AND NORTHWEST OF THE MULTI-MODEL CONSENSUS BASED ON A
BALANCE BETWEEN THE INTERPOLATED TRACKERS AND THE ENSEMBLE GUIDANCE
THAT HAS MULTIPLE SOLUTIONS WEST OF THE TRACK CONSENSUS. THE
INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT THE TYPHOON INTENSITY
WILL STAGNATE OVER THE NEXT 12 HOURS BEFORE WEAKENING UNDER
ELEVATED VERTICAL WIND SHEAR, COOL SEA SURFACE TEMPERATURES, AND
ULTIMATE EXTRATROPICAL TRANSITION.

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