WDPN33 PGTW 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (NEOGURI) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.5N 151.4E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 293 NM NORTH-NORTHWEST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
WEAKENING BANDING ALONG THE WESTERN PERIPHERY OF TYPHOON (TY) 25W.
THE EROSION IS ALSO EVIDENT IN A 211029Z METOP-B MHS 89GHZ
MICROWAVE IMAGE HIGHLIGHTING THE STRONGEST CONVECTION ALONG THE
EASTERN PERIPHERY AND A SLIGHT EASTWARD TILT. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED
EIR AND MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 120 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: A COMPETING STEERING ENVIRONMENT
BETWEEN TWO RIDGES

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 122 KTS AT 210824Z
   CIMSS ADT: 109 KTS AT 211130Z
   CIMSS AIDT: 106 KTS AT 211130Z
   CIMSS D-MINT: 114 KTS AT 211201Z
   CIMSS D-PRINT: 110 KTS AT 211230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 25W WILL CONTINUE TO GRADUALLY CURVE TO A
NORTHEASTWARD TRACK OVER THE NEXT 12 HOURS. DURING THE
NORTHEASTWARD TRACK BETWEEN TAU 12-48, THE TRACK MOTION WILL BE
SLOW AND IRREGULAR DUE TO A COMPLEX STEERING ENVIRONMENT BETWEEN A
SUBTROPICAL RIDGE TO THE EAST AND A SUBTROPICAL RIDGE TO THE WEST.
AFTER TAU 72, TY 25W WILL INCREASE SPEED NORTHEASTWARD WHILE
REMAINING IN THE COMPETING STEERING ENVIRONMENT. WHILE TRACKING 
SLOWLY DURING THE NEXT 48 HOURS, TY 25W WILL WEAKEN DUE TO 
SIGNIFICANT UPWELLING OF COOL WATER. ADDITIONALLY, AN APPROACHING 
TROUGH FROM THE NORTHWEST WILL INCREASE VERTICAL WIND SHEAR 
UNFAVORABLY ABOVE 20KTS, FURTHERING THE RATE OF WEAKENING THROUGH THE 
END OF THE FORECAST. IT IS EVIDENT THAT THE THERMAL BOUNDARY REMAINS 
ON THE NORTHERN SIDE OF THE SYSTEM UNTIL TAU 72, WHEN TY 25W BEGINS 
EXTRATROPICAL TRANSITION DUE TO INTERACTION WITH A MAJOR SHORTWAVE 
TROUGH. TY 25W WILL BECOME FULLY EXTRATROPICAL BY THE END OF THE 
FORECAST PERIOD.

MODEL DISCUSSION: SIMILARLY TO THE LAST WARNING CYCLE, DETERMINISTIC 
MODEL GUIDANCE HAS A LARGE BIFURCATION OF MODEL SOLUTIONS DEPENDING 
SOLELY ON THE STRENGTH OF THE RIDGE TO THE WEST AND WHETHER THE 
UPSTREAM TROUGH EFFECTIVELY BREAKS IT DOWN. IF THE RIDGE IS NOT 
BROKEN DOWN, THERE ARE ALTERNATE SCENARIOS WHERE THE SYSTEM REMAINS 
IN A QUASI-STATIONARY PERIOD FOR LONGER OR EVEN TRACKS TO THE 
SOUTHWEST RATHER THAN NORTHEAST. THE INTENSITY GUIDANCE IS EQUALLY AS 
SPREAD AND IS TIED DIRECTLY TO THE TRACK UNCERTAINTY.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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