WDXS32 PGTW 190300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (SEAN) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.5S 116.1E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 202 NM NORTHEAST OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS STRONG BURSTS 
OF CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). 
SPIRAL BANDS OF CONVECTION HAVE TIGHTENED IN ON THE CENTER OF THE 
SYSTEM OVER THE PAST 6 HOURS. THE CURRENT ENVIRONMENT IS ANALYZED TO 
BE HIGHLY FAVORABLE, SUPPORTED BY MODERATE RADIAL OUTFLOW, LOW 
VERTICAL WIND SHEAR, AND WARM SEA SURFACE TEMPERATURES. THE INITIAL 
INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON 
STRUCTURAL DEVELOPMENT, SUPPORTED BY SURFACE OBSERVATION FROM THE 
DAMPIER ARCHIPELAGO SHOWING 47 KTS WINDS AT 190000Z. THE INITIAL 
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PGTW RADAR FIX, 
CONSISTENT WITH 182323Z GMI COLOR 37 GHZ MICROWAVE IMAGE.

INITIAL WIND RADII BASIS: PERSISTENCE AND SURFACE OBSERVATIONS

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE DEVELOPING OVER
WESTERN AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   APRF: T2.5 - 35 KTS
   CIMSS ADT: 43 KTS AT 190030Z
   CIMSS AIDT: 37 KTS AT 190030Z
   CIMSS D-PRINT: 41 KTS AT 190030Z

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: 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 (SEAN) IS FORECAST TO CONTINUE ON A
SOUTHWESTWARD TRACK ALONG THE NORTHWESTERN PERIPHERY OF A
STRENGTHENING STR TO THE SOUTHEAST. THE ENVIRONMENTAL CONDITIONS
REMAIN HIGHLY FAVORABLE FOR CONTINUED DEVELOPMENT OVER THE NEXT 24-36 
HOURS. AS A RESULT, RAPID INTENSIFICATION IS STILL FORECAST TO OCCUR 
OVER THE NEXT 24 HOURS TO AN INTENSITY OF 80 KTS AT TAU 24. AROUND TAU 
48 THE SEA SURFACE TEMPERATURES ARE FORECAST TO DROP BELOW 24 CELSIUS, 
WHICH WHEN COMBINED WITH SIGNIFICANT DRY AIR ENTRAINMENT, WILL LEAD TO 
A RAPID WEAKENING TREND AND AN EVENTUAL DISSIPATION AROUND TAU 120. 
HOWEVER, THERE IS A POSSIBILITY THAT IF THE VORTEX CAN HOLD TOGETHER 
LONG ENOUGH, EXTRATROPICAL TRANSITION COULD OCCUR BEFORE THE 
DISSIPATION SCENARIO COMPLETES.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN GOOD
AGREEMENT WITH A CROSS-TRACK SPREAD OF 110 NM AT TAU 72. THE JTWC 
TRACK FORECAST IS PLACED CLOSE TO CONSENSUS WITH HIGH CONFIDENCE 
THROUGH TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. RAPID INTENSIFICATION 
(RI) AIDS ARE STILL INDICATING HIGH RI POTENTIAL FOR THE NEXT 36 
HOURS. THE DETERMINISTIC GUIDANCE DOES SHOW SOME UNCERTAINTY, WITH THE 
REMAINDER OF GUIDANCE SUGGESTING A PEAK INTENSITY RANGING FROM 65 KTS 
(GFS) TO 80 KTS (HAFS-A). THE JTWC FORECAST IS THEREFORE ASSESSED WITH 
MEDIUM CONFIDENCE BETWEEN THE MULTI-MODEL CONSENSUS AND THE AVERAGE OF 
THE RI TRACKERS. AFTER TAU 36, THE DRASTICALLY DETERIORATING 
ENVIRONMENT WILL CONTRIBUTE TO RAPID WEAKENING AS INDICATED BY ALL 
AVAILABLE GUIDANCE.

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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