WDXS31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (FIVE)        
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.9S 131.2E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 157 NM NORTH OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 05S HAS CONTINUED TO CONSOLIDATE UNDER FAVORABLE 
ENVIRONMENTAL CONDITIONS TO INCLUDE RADIAL OUTFLOW, LOW VERTICAL WIND 
SHEAR AND WARM SST VALUES. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY DEPICTS A SYMMETRIC CENTRAL DENSE OVERCAST FEATURE OBSCURING 
THE LOW-LEVEL CIRCULATION CENTER (LLCC), WITH PERSISTENT DEEP 
CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE. ANIMATED RADAR IMAGERY 
FROM THE DARWIN RADAR REVEALS CURVED BANDING OVER THE SOUTHERN 
SEMICIRCLE WRAPPING WEAKLY OVER THE NORTHERN QUADRANT OF A DEFINED 
LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. A 
PARTIAL 181209Z ASCAT-B IMAGE ALSO SUPPORTS THE INITIAL POSITION, WITH 
A SWATH OF 30-40 KNOT SOUTHERLY WINDS OVER THE WESTERN EDGE OF THE 
CENTER. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON AN AVERAGE OF SUBJECTIVE AND OBJECTIVE INTENSITY 
ESTIMATES RANGING FROM 34 TO 45 KNOTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL NEAR-EQUATORIAL RIDGE
(NER) POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   ADRM: T2.5 - 35 KTS
   CIMSS ADT: 43 KTS AT 181140Z
   CIMSS AIDT: 34 KTS AT 181140Z
   CIMSS D-MINT: 39 KTS AT 180854Z
   CIMSS D-PRINT: 43 KTS AT 181230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 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 05S WILL TRACK SLOWLY EASTWARD OVER THE NEXT 36 
HOURS ALONG THE SOUTHERN PERIPHERY OF THE NER. THE SYSTEM IS FORECAST 
TO PEAK TO ABOUT 60 KNOTS DURING THIS TIMEFRAME, WITH GENERALLY 
FAVORABLE CONDITIONS PERSISTING THROUGH ABOUT TAU 24. NEAR TAU 24, 
VERTICAL WIND SHEAR (VWS) IS FORECAST TO INCREASE TO HIGH (25-30 KNOTS) 
LEVELS, WHICH WILL TILT THE VORTEX SOUTHWESTWARD, WITH DRY AIR 
ENTRAINING INTO THE EASTERN QUADRANT OF THE CORE. THIS WILL INITIATE A 
GRADUAL WEAKENING TREND THROUGH TAU 72. AFTER TAU 72, THE SUBTROPICAL 
RIDGE TO THE SOUTH AND EAST IS EXPECTED TO BROADEN AND STRENGTHEN 
BECOMING THE DOMINANT STEERING INFLUENCE THROUGH THE REMAINDER OF THE 
FORECAST PERIOD. THIS WILL DRIVE THE SYSTEM SOUTHWESTWARD TO WEST-
SOUTHWESTWARD THROUGH TAU 120. AFTER TAU 72, TC 05S WILL SKIRT THE 
NORTHERN COAST OF AUSTRALIA, WITH NO CHANGE TO THE INTENSITY THROUGH 
TAU 96. AFTER TAU 96, THE SYSTEM WILL TRACK BACK OVER WATER WITH A 
SLIGHT INTENSIFICATION TO 50 KNOTS BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT LENDING 
MEDIUM CONFIDENCE TO THE JTWC TRACK FORECAST, WITH SIGNIFICANT 
UNCERTAINTY IN THE TIMING OF THE SHARP SOUTHWARD AND WESTWARD TURNS. 
THE 180600Z GEFS AND EPS RUNS ALSO REFLECT SIMILAR UNCERTAINTY. DUE TO 
THE TRACK UNCERTAINTY AND PROXIMITY TO LAND, THERE IS MEDIUM CONFIDENCE 
IN THE JTWC INTENSITY FORECAST, WITH RELIABLE GUIDANCE INDICATING A 
FAIRLY WIDE SPREAD OF PEAK INTENSITY VALUES RANGING FROM 50 TO 70 KNOTS 
IN THE TAU 24 TO TAU 36 PERIOD. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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