WDXS31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (FINA)       
WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.2S 129.3E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 103 NM WEST-SOUTHWEST OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SPIRAL BANDING 
WRAPPING INTO A WELL-DEFINED CLOUD-FILLED EYE. ANIMATED RADAR IMAGERY 
CONTINUES TO REVEAL TIGHTLY-CURVED BANDING AND A SMALL, WELL-DEFINED 
EYE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. 
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH RADIAL OUTFLOW, 
ENHANCED POLEWARD OUTFLOW, LOW VERTICAL WIND SHEAR AND WARM SST 
VALUES. TOTAL PRECIPITABLE WATER IMAGERY SHOWS EXTENSIVE VERY DRY AIR 
OVER THE SOUTHWESTERN PERIPHERY OF THE SYSTEM, WHICH IS ENTRAINING 
INTO THE NORTHWEST QUADRANT OF THE SYSTEM. THE INITIAL INTENSITY OF 90 
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE CIMSS OBJECTIVE 
INTENSITY ESTIMATES. THE SYSTEM HAS WEAKENED SLIGHTLY, WITH THE PGTW 
DATA-T ESTIMATE AT T5.0 (90 KNOTS) AND CURRENT INTENSITY ESTIMATE AT 
5.5 (102 KNOTS). ADRM IS SLIGHTLY HIGHER AT A T5.5 (102 KNOTS). 
THEREFORE, THERE IS SOME VARIABILITY AND UNCERTAINTY IN THE INITIAL 
INTENSITY.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   ADRM: T5.5 - 102 KTS
   CIMSS SATCON: 83 KTS AT 230600Z
   CIMSS ADT: 90 KTS AT 230600Z
   CIMSS AIDT: 91 KTS AT 230600Z
   CIMSS D-PRINT: 88 KTS AT 230310Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: WEAK DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 05S IS FORECAST TO CONTINUE 
TRACKING SOUTHWESTWARD THROUGH TAU 12 ALONG THE NORTHWESTERN PERIPHERY 
OF THE STR, WITH A BRIEF PERIOD OF INTENSIFICATION POSSIBLE BEFORE 
SIGNIFICANT DRY AIR ENTRAINMENT COMMENCES. AFTER TAU 12, TC 05S WILL 
TURN WEST-SOUTHWESTWARD TO WESTWARD THROUGH TAU 48 ALONG THE NORTHERN 
PERIPHERY OF A WEAK EXTENSION OF THE STR, WITH LANDFALL EXPECTED NEAR 
TAU 36. THE SYSTEM WILL RAPIDLY WEAKEN DUE TO INCREASING VERTICAL WIND 
SHEAR, DRY AIR ENTRAINMENT AND FRICTIONAL EFFECTS. TC 05S WILL 
DISSIPATE BY TAU 72 WITH A SLOW TRACK SOUTHWESTWARD TO SOUTHWARD OVER 
LAND.  

MODEL DISCUSSION: DETERMINISTIC GUIDANCE IS IN BETTER AGREEMENT, WITH 
THE BULK OF THE GUIDANCE NOW SUPPORTING THE JTWC TRACK PHILOSOPHY. THE 
230000Z GEFS AND EPS RUNS SHOW A WIDER SPREAD WITH INCREASING 
UNCERTAINTY IN THE EXACT TRACK. HOWEVER, THE BULK OF THE SOLUTIONS ARE 
OVERLAND. RELIABLE INTENSITY GUIDANCE SHOWS SOME POTENTIAL FOR THE 
BRIEF REINTENSIFICATION PERIOD THROUGH TAU 12, WITH TIGHT AGREEMENT ON 
THE RAPID WEAKENING PHASE OF THE FORECAST AFTER TAU 12. 

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