WDXS32 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (SEAN) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.6S 110.8E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 184 NM WEST OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 52 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS MOSTLY MAINTAINED ITS CONVECTIVE SIGNATURE OVER THE LAST SIX
HOURS WITH ITS COMPACT COLD CENTRAL COVER THAT ALSO MAINTAINED A
SECONDARY EYEWALL AROUND ITS 9-NM PINHOLE EYE. THE INITIAL POSITION IS 
PLACED WITH HIGH CONFIDENCE BASED ON THE PINHOLE EYE. THE INITIAL
INTENSITY OF 115KTS IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON
THE HIGH END OF AGENCY DVORAK AND AUTOMATED INTENSITY ESTIMATES TO
REFLECT THE MOSTLY SUSTAINED 6-HR EIR CONVECTIVE SIGNATURE. ANALYSIS 
INDICATES A FAVORABLE ENVIRONMENT WITH STRONG RADIAL OUTFLOW AND LOW 
VWS SLIGHTLY OFFSET BY COOLING SST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   DEMS: T6.0 - 115 KTS
   APRF: T5.5 - 102 KTS
   CIMSS SATCON: 105 KTS AT 200606Z
   CIMSS ADT: 115 KTS AT 201130Z
   CIMSS ADT: 106 KTS AT 201130Z
   CIMSS DPNT: 95 KTS AT 201130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC SEAN WILL CONTINUE TO TRACK SOUTHWESTWARD
THEN SOUTHWARD AROUND THE NORTHWESTERN THEN WESTERN PERIPHERY OF
THE STEERING STR. THE ENVIRONMENT WILL BECOME UNFAVORABLE RESULTING
IN A GRADUAL EROSION WITH AN EYEWALL REPLACEMENT CYCLE EXPECTED TO 
COMMENCE. THIS, PLUS THE CONTINUED COOLING SST, INCREASING VWS AND, 
EVENTUALLY, DRY AIR INTRUSION WILL LEAD TO DISSIPATION BY TAU 96.

MODEL DISCUSSION: AVAILABLE NUMERICAL MODELS ARE IN TIGHT AGREEMENT
WITH THE MAIN PACK AT AN EVEN AND GRADUAL SPREAD TO A MERE 51NM BY
TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK
FORECAST. AFTERWARD, THE MODELS SPREAD OUT WIDER AND MORE UNEVENLY
TO OVER 400NM WITH UEMN THE EXTREME RIGHT-OF-TRACK OUTLIER, LENDING
ONLY MEDIUM CONFIDENCE TO THE EXTENDED PORTION OF THE TRACK FORECAST 
THAT IS LAID TO THE LEFT OF CONSENSUS TO OFFSET UEMN. THERE IS ONLY 
MEDIUM CONFIDENCE IN THE INTENSITY FORECAST DUE TO THE UNCERTAINTIES 
ASSOCIATED WITH RAPID WEAKENING THAT USUALLY FOLLOWS AFTER RAPID 
INTENSIFICATION. 

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