WDPN33 PGTW 172100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 38.6N 149.7E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 412 NM EAST-SOUTHEAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 21 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
08W (AMPIL) AS CONTINUING TO UNDERGO FURTHER WEAKENING AS INCREASED
VERTICAL TILT THROUGH THE CENTRAL STRUCTURE HAS BECOME MORE EVIDENT
OVER THE LAST SIX HOURS DUE TO STRONG VERTICAL WIND SHEAR (VWS) AND
THE REMAINING CONVECTIVE SUPPORT HAS NOW TRANSITIONED POLEWARD AND
EASTWARD OF THE SYSTEM. ALTHOUGH MODERATE POLEWARD AND EQUATORWARD
OUTFLOW ALOFT IS OBSERVED IN ANIMATED WATER VAPOR IMAGERY, A
171652Z AMSR-2 PASS HAS CONFIRMED A RAPIDLY WEAKENING SYSTEM WITH
AN EXPANDING WIND FIELD AS TY 08W TRACKS TO THE EAST-NORTHEAST INTO
COOLER SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON EASTWARD EXTRAPOLATION FROM
THE AFOREMENTIONED AMSR-2 PASS. THE INITIAL INTENSITY IS ASSESSED
WITH LOW CONFIDENCE BASED ON THE WIDE RANGE OF INTENSITIES
ILLUSTRATED ON THE AMSR-2 PASS, AGENCY FIX ESTIMATES, AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SAR DATA.

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 71 KTS AT 1730Z
   CIMSS ADT: 47 KTS AT 1800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 24-26 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 08W (AMPIL) IS FORECASTED TO CONTINUE
QUICKLY TRACKING TO THE NORTHEAST AS THE MID-LATITUDE WESTERLIES
AID IN THE EASTWARD PROGRESS AND RAPID WEAKENING PHASE OF THE
SYTEM. THROUGHOUT THE REMAINING 36 HOURS OF THE FORECAST PERIOD,
THE TYPHOON WILL CONTINUE TO RAPIDLY WEAKEN AND UNDERGO
EXTRA-TROPICAL TRANSITION AS THE ENVIRONMENT INTRODUCES COOLER SST
BELOW 25 C, INCREASED VWS EXCEEDING 30 KNOTS, AND AMPLIFIED DRY-AIR
ENTRAINMENT FROM THE WESTERN QUADRANT BETWEEN 700MB AND 300MB. BY
THE END OF THE FORECAST PERIOD, TY 08W IS EXPECTED TO BECOME
COMPLETELY EXTRA-TROPICAL AS THE LOW-LEVEL CIRCULATION (LLC)
BECOMES DECOUPLED FROM ANY REMAINING SUPPORTIVE CONVECTION.

MODEL DISCUSSION: MODEL GUIDANCE IS IN VERY GOOD AGREEMENT ON THE
TRACK FORECAST THROUGH THE REMAINDER OF THE FORECAST PERIOD OF 36
HOURS, AND THE JTWC FORECAST IS TIGHTLY ALIGNED WITH THE
MULTI-MODEL CONSENUS. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT,
WITH CONSENSUS MEMBERS IN CONCURRENCE THAT TY 08W WILL CONTINUE
RAPIDLY WEAKENING AND BECOME EXTRA-TROPICAL BY TAU 36, LENDING HIGH
CONFIDENCE TO THE JTWC FORECAST.

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