WDXS32 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (SEAN) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.0S 112.3E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 127 NM NORTHWEST OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PINHOLE 10 NM 
EYE ENCOMPASSED BY A HIGHLY COMPACT CENTRAL DENSE OVERCAST AND COLD 
CLOUD TOPS SURROUNDING THE EYEWALL. ENVIRONMENTAL CONDITIONS REMAIN 
HIGHLY FAVORABLE FOR TROPICAL DEVELOPMENT, INCLUDING WARM SEA SURFACE 
TEMPERATURES (SST), LOW VERTICAL WIND SHEAR (VWS), AND STRONG RADIAL 
OUTFLOW. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
THE PGTW RADAR FIX, AS WELL AS THE CLEARLY IDENTIFIABLE PINHOLE EYE IN 
ANIMATED MSI. THE INITIAL INTENSITY OF 95 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON THE CIMSS AUTOMATED INTENSITY ESTIMATES AND AGENCY 
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE FROM EARLIER SAR DATA AND 
SURFACE OBSERVATIONS. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   APRF: T5.0 - 90 KTS
   CIMSS ADT: 82 KTS AT 200000Z
   CIMSS AIDT: 78 KTS AT 200000Z
   CIMSS D-MINT: 100 KTS AT 192239Z
   CIMSS D-PRINT: 84 KTS AT 200000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL

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: TC 10S IS EXPECTED TO CONTINUE INTENSIFYING
OVER THE NEXT 12 HOURS, AS IT TRACKS WEST-SOUTHWESTWARD, ALONG THE
NORTHWESTERN PERIPHERY OF A DEEP-LAYERED STR. AS THE SST BEGIN TO COOL 
AFTER TAU 12, THE SYSTEM WILL BEGIN ITS WEAKENING TREND. THE PROCESS
WILL RAPIDLY ACCELERATE AFTER TAU 24 AS THE ENVIRONMENT BECOMES
INCREASINGLY HOSTILE, WITH INCREASING VWS AND MORE DRY AIR ENTERING
THE CORE OF THE CYCLONE. BETWEEN TAUS 48 AND 72, ANOTHER STR TO THE
SOUTHWEST OF THE SYSTEM WILL CONTRIBUTE TO ITS SLOWER MOTION. SHORTLY 
AFTER THAT, THE PREDOMINANT DEEP-LAYERED STR OVER AUSTRALIA WILL 
ENABLE TC 10S TO CONTINUE TRANSITING AROUND ITS WESTERN PERIPHERY. AS 
SOON AS THE SYSTEM ROUNDS THE AXIS OF THE RIDGE BY TAU 72, IT WILL 
BEGIN TO DISSIPATE AND IS FORECAST TO COMPLETELY DISSIPATE BY TAU 96.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT IN
REGARD TO BOTH TRACK AND INTENSITY. THE CROSS-TRACK SPREAD AT TAU
72 IS APPROXIMATELY 80 NM DISCOUNTING THE PRIMARY OUTLIER, THE UKMET
ENSEMBLE. THE REMAINDER OF GUIDANCE IS IN CLOSE AGREEMENT, THEREFORE 
THE JTWC TRACK FORECAST IS ASSESSED WITH HIGH CONFIDENCE THROUGH TAU 
72 AND MEDIUM CONFIDENCE THEREAFTER. IN REGARD TO THE INTENSITY, THE 
INITIAL 12 HOUR GUIDANCE VARIES BETWEEN MODELS WITH COAMPS-TC, GFS, 
AND HWRF FORECASTING WEAKENING, WHILE HAFS-A SUGGESTS FURTHER 
INTENSIFICATION TO A PEAK OF AROUND 105 KTS. THE JTWC FORECAST IS 
PLACED CLOSER TO HAFS-A WITH MEDIUM CONFIDENCE, DUE TO THE SHORT 
WINDOW FOR POTENTIAL INTENSIFICATION OVER THE NEXT 12 HOURS, PRIOR TO 
WEAKENING. AFTER TAU 12, THERE IS SIGNIFICANTLY LESS UNCERTAINTY IN 
REGARD TO THE GENERAL WEAKENING TREND, AS ALL GUIDANCE IS CONSISTENT. 
HOWEVER THE TIMELINE OF DISSIPATION REMAINS BETWEEN 72 AND 120 HOURS 
AMONG THE GUIDANCE, THEREFORE JTWC FORECAST IS PLACED AT THE MIDPOINT 
OF 96 HOURS.

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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