WDXS32 PGTW 190900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (SEAN) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.6S 115.3E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 175 NM NORTH-NORTHEAST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS
SLIGHTLY INTENSIFIED OVER THE LAST SIX HOURS AS EVIDENCED BY MORE
CONSOLIDATED FEEDER BANDS WRAPPING INTO THE CENTRAL DENSE OVERCAST
THAT IS OBSCURING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE DEFINED 
LLCC IN THE COMPOSITE RADAR LOOP FROM THE ABOM KARRATHA RADAR SITE THAT 
LINED UP PERFECTLY WITH THE MICROWAVE EYE IN THE 190539Z AMSR2 IMAGE. 
THE INITIAL INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON 
THE HIGH END OF AGENCY AND AUTOMATED DVORAK INTENSITY ESTIMATES TO 
REFLECT THE IMPROVED CONVECTIVE SIGNATURE. ANALYSIS INDICATES A HIGHLY 
FAVORABLE ENVIRONMENT WITH WARM SST, MODERATE RADIAL OUTFLOW, AND LOW 
VWS.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: BUILDING SUBTROPICAL RIDGE (STR) TO
THE
SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS ADT: 53 KTS AT 190530Z
   CIMSS AIDT: 43 KTS AT 190530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE 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 TRACK SOUTHWESTWARD THEN
SOUTHWARD AROUND THE NORTHWESTERN THEN WESTERN PERIPHERY OF THE
STEERING STR. THE HIGHLY FAVORABLE ENVIRONMENT WILL FUEL RAPID
INTENSIFICATION TO A PEAK OF 80KTS AT TAUS 24-36. AFTERWARD, COOLING 
SST, INCREASING VWS AND DRY AIR INTRUSION WILL GRADUALLY
ERODE THE SYSTEM DOWN TO DISSIPATION BY TAU 120. 

MODEL DISCUSSION: AVAILABLE NUMERICAL MODELS ARE IN TIGHT AGREEMENT
WITH AN EVEN AND GRADUAL SPREAD TO A MERE 95NM BY TAU 72, LENDING
HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. AFTERWARD, 
THE MODELS SPREAD OUT WIDER AND MORE UNEVENLY TO 305NM, LENDING ONLY 
MEDIUM CONFIDENCE TO THE EXTENDED PORTION OF THE TRACK FORECAST. THERE 
IS ONLY MEDIUM CONFIDENCE IN THE INTENSITY FORECAST DUE TO THE 
UNCERTAINTIES ASSOCIATED WITH 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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