WDXS31 PGTW 231500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 17S (SEVENTEEN) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.1S 120.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 194 NM NORTH-NORTHWEST OF BROOME,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 17S WITH WIDESPREAD CURVED CONVECTION SLOWLY
CONSOLIDATING AROUND THE OBSCURED LOW-LEVEL CIRCULATION CENTER.
MOST OF THE ASSOCIATED CONVECTION THROUGHOUT THE SYSTEMS LOW-LEVEL
CIRCULATION IS RELATIVELY SHORT-LIVED, BUT PERSISTENT THROUGHOUT
THE FORMATIVE BANDING. THE ENVIRONMENT REMAINS CONDUCIVE FOR
FURTHER INTENSIFICATION, WITH LOW VERTICAL WIND SHEAR (VWS) OF LESS
THAN 10 KTS, WARM SEA SURFACE TEMPERATURES BETWEEN 29-30 C, AND
GOOD EQUATORWARD OUTFLOW ALOFT. THE INITIAL POSITION AND INTENSITY
IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 231248Z METOP-B ASCAT
PASS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) CENTERED TO
THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   APRF: T2.5 - 35 KTS
   CIMSS ADT: 47 KTS AT 231130Z
   CIMSS AIDT: 37 KTS AT 231130Z
   CIMSS D-MINT: 28 KTS AT 231207Z
   CIMSS D-PRINT: 33 KTS AT 231230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 17S IS FORECASTED TO TRACK SOUTHEAST
THROUGHOUT THE NEXT 18-24 HOURS, ALONG THE SOUTHEASTERN PERIPHERY
OF THE NER DIRECTLY TO THE NORTH BEFORE MAKING LANDFALL BEFORE TAU
24 NEAR THE DAMPIER PENINSULA. POST LANDFALL, TC 17S IS EXPECTED TO
RAPIDLY DISSIPATE AS A SUBTROPICAL RIDGE (STR) LOCATED OVER CENTRAL
AUSTRALIA DRIVES THE SYSTEM SOUTHWARD INTO THE END OF THE FORECAST
PERIOD. REGARDING INTENSITY, TC 17S IS FORECASTED TO FURTHER
CONSOLIDATE AND QUICKLY INTENSIFY TOWARD 55 KTS OVER THE NEXT 12
HOURS AS THE LOW-LEVEL CIRCULATION CENTER BECOMES INCREASINGLY
DEFINED. NEAR TAU 18, THE CYCLONE IS EXPECTED TO MAKE LANDFALL AND
BEGIN ITS TERMINAL WEAKENING PHASE. TC 17S IS FORECASTED TO
CONTINUE WEAKENING AFTER LANDFALL, DISSIPATING TO 30 KTS BETWEEN
TAU 36 AND TAU 48 DUE TO TOPOGRAPHICAL INTERACTION.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE AND ARTIFICIAL
INTELLIGENCE (AI) GUIDANCE REMAINS IN VERY GOOD AGREEMENT
THROUGHOUT THE ENTIRETY OF THE FORECAST PERIOD, ILLUSTRATING A 42
NM CROSS-TRACK SPREAD INTO LANDFALL OVER THE DAMPIER PENINSULA. THE
JTWC TRACK FORECAST IS ALIGNED JUST TO THE WEST OF THE JTWC
CONSENSUS, CLOSE TO RELIABLE DETERMINISTIC AND AI SOLUTIONS,
LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST POSITION.
REGARDING INTENSITY, RAPID INTENSIFICATION SOLUTIONS CONTINUE TO
TRIGGER FOR THE SECOND CONSECUTIVE CYCLE, CHARACTERIZING QUICK
INTENSIFICATION TOWARD 55 KTS BY TAU 12. NEAR TAU 18, ALL JTWC
CONSENSUS MEMBERS SHOW A RAPID WEAKENING PHASE AFTER LANDFALL.
THEREFORE, THE JTWC INTENSITY FORECAST HAS BEEN ASSESSED WITH
MEDIUM CONFIDENCE AND PLACED CLOSELY TOWARD THE RAPID
INTENSIFICATION SOLUTIONS INTO TAU 12, AND THEN ALIGNED CLOSELY
WITH THE JTWC INTENSITY CONSENSUS BETWEEN TAU 12 AND TAU 48.  

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM//
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