WDXS31 PGTW 281500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (CHENESO)    
WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.7S 41.5E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 222 NM SOUTH-SOUTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 08S INTENSIFIED AND PEAKED AT 85 KNOTS NEAR
280242Z BASED ON A RADARSAT-2 SAR IMAGE (27 DEGREE INCIDENCE
ANGLE), WHICH SHOWED A SWATH OF 80-85 KNOT WINDS. SINCE THAT TIME,
THE SYSTEM HAS WEAKENED SLIGHTLY DUE TO INCREASING VERTICAL WIND
SHEAR. AS EVIDENT IN ANIMATED ENHANCED INFRARED SATELLITE IMAGERY,
AN IRREGULAR CDO IS OBSCURING THE LOW-LEVEL CIRCULATION, HOWEVER, A
281037Z AMSR2 WINDSPEED IMAGE SHOWS A WELL-DEFINED WIND MINIMUM
SUPPORTING THE CURRENT POSITION AND MAXIMUM WINDS OF 70-77 KNOTS.
THE INITIAL INTENSITY OF 75 KTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE AMSR2 DATA AS WELL AS CONCURRENT T4.5 ESTIMATES FROM
ALL AGENCIES. UPPER-LEVEL CONDITIONS HAVE DEGRADED WITH INCREASING
UPPER-LEVEL WESTERLIES OVER THE SYSTEM, HOWEVER, ROBUST POLEWARD
OUTFLOW INTO A JET TO THE SOUTHEAST IS ALLOWING DEEP CONVECTION TO
MAINTAIN OVER AND TO THE SOUTH OF THE CENTER.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED STEERING RIDGE POSITIONED
TO THE EAST AND SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T4.5 - 77 KTS
   CIMSS SATCON: 78 KTS AT 281052Z
   CIMSS ADT: 82 KTS AT 281200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: WITH THE APPROACH OF A MAJOR SHORTWAVE TROUGH
TO THE SOUTHWEST, THE SUBTROPICAL RIDGE HAS REALIGNED TO THE EAST
AND SOUTHEAST ALLOWING TC 08S TO TRACK STEADILY SOUTHWARD OVER THE
PAST 12 HOURS. TC 08S WILL RECURVE SOUTHEASTWARD AND ACCELERATE
ALONG THE NORTHEASTERN PERIPHERY OF THIS TROUGH WITHIN THE STRONG
NORTHWESTERLY FLOW THROUGH THE FORECAST PERIOD. NEAR TAU 24, TC 08S
WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH A
STRONG BAROCLINIC ZONE AND INCREASING VERTICAL WIND SHEAR. THE
SYSTEM WILL QUICKLY COMPLETE ETT AS IT GAINS FRONTAL CHARACTERISTICS 
AND TRACKS UNDER THE MIDLATITUDE JET. THE 280600Z FSU CYCLONE PHASE 
CHARTS ALSO SHOW ETT COMPLETING BY 301200Z.   

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
WITH A 55-70NM SPREAD IN SOLUTIONS FROM TAU 36 TO TAU 48.
PROBABILISTIC GUIDANCE ALSO REMAINS IN TIGHT AGREEMENT AND SHOWS A
HIGH PROBABILITY OF A GALE-FORCE EXTRA-TROPICAL LOW AND PERHAPS
STORM-FORCE LOW TRACKING SOUTHEASTWARD AFTER TAU 48. CONSEQUENTLY,
THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. RELIABLE
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH ALL GUIDANCE
INDICATING A SHARP WEAKENING TREND THROUGH THE FORECAST PERIOD.  

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