WDXS31 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (BATSIRAI) 
WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.9S 44.4E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 236 NM EAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: N/A

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH WELL DEFINED LOW
LEVEL CLOUD BANDING TIGHTLY WRAPPING INTO THE LLCC. ANIMATED 
ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND A 061104Z AMSR2 89GHZ 
MICROWAVE IMAGE DEPICT A DRAMATIC WEAKENING OF THE CORE CONVECTIVE 
STRUCTURE WITH THE PRIMARY SPIRAL BANDING PERSISTING OVER THE 
SOUTHERN SEMICIRCLE. SURFACE OBSERVATIONS FROM TULEAR, MADAGASCAR 
(23.4S 43.7E), APPROXIMATELY 50NM SOUTHWEST OF THE CENTER, SHOW AN
INCREASE IN SOUTHERLY WINDS TO 24 KNOTS AND A SLP VALUE OF 992.8MB. 
THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE 
MSI AND AMSR2 IMAGE. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED 
WITH MEDIUM CONFIDENCE BASED ON THE OVERALL BANDING STRUCTURE OF THE 
SYSTEM.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: NO CURRENT ESTIMATES SINCE SYSTEM 
IS OVERLAND

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 08S (BATSIRAI) WILL FINISH TRAVERSING THE
ISLAND OF MADAGASCAR UNDER THE STEERING INFLUENCE OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. AS THE SYSTEM ENTERS THE
MOZAMBIQUE CHANNEL THE ENVIRONMENT WILL BE CONDUCIVE TO 
INTENSIFICATION WITH LOW VERTICAL WIND SHEAR (VWS), WARM SEA
SURFACE TEMPERATURES AND STRONG POLEWARD OUTFLOW ALOFT. TRACK SPEEDS 
WILL REMAIN SLOW AS THE SYSTEM BEGINS TO DEEPEN AND TRACK SOUTHWARD
EVENTUALLY PEAKING AT 55 KNOTS AT TAU 24. AFTER TAU 36, AN
EASTWARD PROPAGATING TROUGH REORIENTS THE STR AND ACCELERATES THE 
SYSTEM SOUTH-SOUTHEASTWARD. TC 08S WILL GRADUALLY WEAKEN DUE TO 
INCREASING NORTHERLY VERTICAL WIND SHEAR, SIGNIFICANT DRY AIR 
ENTRAINMENT AND COOLING SST (24-26C). AFTER TAU 48, THE SYSTEM IS 
FORECAST TO BEGIN SUBTROPICAL TRANSITION AND IT INTERACTS WITH THE 
AFOREMENTIONED UPPER LEVEL TROUGH AND WEAK BAROCLINIC ZONE. NEAR TAU 
72, THE SYSTEM WILL TRANSITION INTO A SUBTROPICAL CYCLONE AS IT 
APPROACHES THE SUBTROPICAL JET.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, NUMERICAL MODELS
ARE IN UNANIMOUS AGREEMENT WITH NO MORE THAN A 35NM SPREAD
THROUGHOUT THE FORECAST PERIOD. WITH THE EXCEPTION OF DSHN
(DECAY-SHIPS WITH NAVGEM FIELDS), RELIABLE MODEL INTENSITY GUIDANCE 
SUPPORTS THE BRIEF REINTENSIFICATION PERIOD AND PEAK IN INTENSITY 
BETWEEN TAU 24 AND TAU 36, AND THE SLOW WEAKENING TREND THROUGH TAU 
72 AS THE ENVIRONMENT STEADILY DEGRADES.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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