WDXS31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (BATSIRAI) 
WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.4S 52.6E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 166 NM WEST-NORTHWEST OF ST DENIS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 52 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN INTENSE, 
HIGHLY SYMMETRICAL SYSTEM WITH DEEP CENTRAL CONVECTION AND A 30-NM 
SHARPLY OUTLINED EYE. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON THE EYE FEATURE, ADJUSTED FOR A SLIGHT TILT AND 
LINED UP WITH A WELL-DEFINED MICROWAVE EYE FEATURE IN THE 041015Z 
ATMS IMAGE. THE INITIAL INTENSITY OF 115KTS IS BASED ON AN OVERALL 
ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES (SEE  BELOW) AND 
CONSISTENT WITH THE SUSTAINED 6-HR CONVECTIVE STRUCTURE. ANALYSIS 
INDICATES THE CYCLONE IS IN A FAVORABLE ENVIRONMENT WITH WARM (28-
29C) SST, STRONG POLEWARD OUTFLOW, AND LOW (10-15KT) VWS. TC 08S IS 
TRACKING ALONG THE NORTHWEST PERIPHERY OF THE DEEP-LAYER STR TO THE 
SOUTH.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE TO THE
SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   CIMSS SATCON: 119 KTS AT 041012Z
   CIMSS ADT: 112 KTS AT 040915Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 BATSIRAI WILL CONTINUE ON ITS CURRENT TRACK
UNDER THE STEERING INFLUENCE OF THE STR, MAKING LANDFALL OVER
CENTRAL MADAGASCAR JUST AFTER TAU 24, CROSS THE ISLAND, AND EXIT
INTO THE MOZAMBIQUE CHANNEL SHORTLY AFTER TAU 48. AFTERWARD, IT
WILL ROUND THE WESTERN EDGE OF THE STR AND TRACK SOUTHWARD. THE
INITIAL FAVORABLE ENVIRONMENT WILL FUEL SLIGHT INTENSIFICATION TO 
120KTS BY TAU 12; AFTERWARD, INTERACTION WITH MADAGASCAR WILL SLOWLY 
THEN RAPIDLY ERODE THE SYSTEM DOWN TO 40KTS PRIOR TO ITS EXIT INTO 
THE CHANNEL. THE WARM SST IN THE CHANNEL WILL RE-INTENSIFY TC 08S TO 
50KTS BY TAU 96. AFTERWARD, REDUCED UPPER LEVEL OUTFLOW AND 
DECREASING SST WILL BEGIN TO WEAKEN IT, DOWN TO 45KTS BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN TIGHT AGREEMENT,
GRADUALLY AND EVENLY SPREADING OUT TO 340NM BY TAU 120 WITH NVGM THE 
NOTABLE RIGHT OF TRACK OUTLIER, LENDING MEDIUM CONFIDENCE TO THE 
JTWC TRACK FORECAST THAT IS LAID NEAR THE MODEL CONSENSUS (CONW) UP 
TO TAU 72 THEN JUST LEFT OF CONW TO OFFSET NVGM. THERE IS ALSO MEDIUM
CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 72, THEN LOW
CONFIDENCE AFTERWARD.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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