WDXS31 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (BATSIRAI) 
WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.8S 49.4E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 156 NM SOUTHEAST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES THAT
THE SYSTEM HAS MAINTAINED A 25NM ROUND EYE AND ITS OVERALL
CONVECTIVE STRUCTURE DESPITE THE PROXIMITY TO THE COAST OF
MADAGASCAR. A 051022Z AMSR2 89GHZ MICROWAVE IMAGE REVEALS SOME
EROSION OF THE EYEWALL AND SPIRAL BANDING OVER THE NORTHERN
SEMICIRCLE, LIKELY DUE TO MID-LEVEL DRY AIR ENTRAINMENT, HOWEVER THE 
EYEWALL AND SPIRAL BANDING OVER THE SOUTHERN SEMICIRCLE ARE
UNAFFECTED. DVORAK ESTIMATES HAVE REMAINED LARGELY STATIC WITH PGTW 
AND FMEE CURRENT INTENSITY ESTIMATES AT 5.5 (102 KNOTS) AND CIMSS 
SATCON AND ADT ESTIMATES RANGING FROM 107-109 KNOTS SUPPORTING THE 
INITIAL INTENSITY OF 100 KTS WITH HIGH CONFIDENCE. SURFACE 
OBSERVATIONS FROM MANANJARY (NEAR 21.2S 48.3E), APPROXIMATELY 62NM 
WSW OF THE CENTER, HAVE STRENGTHENED QUICKLY TO 70 KNOTS WITH SLP 
NEAR 987MB. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE 
BASED ON THE EIR IMAGERY.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   FMEE: T5.5 - 102 KTS
   CIMSS SATCON: 109 KTS AT 051044Z
   CIMSS ADT: 107 KTS AT 051215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 IS FORECAST TO MAKE LANDFALL WITHIN THE
NEXT SIX HOURS AND WILL RAPIDLY WEAKEN AS IT TRACKS ACROSS THE
MOUNTAINOUS TERRAIN OF MADAGASCAR. TC 08S WILL REEMERGE OVER THE
MOZAMBIQUE CHANNEL NEAR TAU 30 BUT WILL ENCOUNTER MARGINALLY
FAVORABLE CONDITIONS WITH INCREASING NORTHERLY VERTICAL WIND SHEAR
AND DRY AIR ENTRAINMENT OFFSET BY FAVORABLE POLEWARD OUTFLOW AND
WARM SEA SURFACE TEMPERATURES. THE SYSTEM WILL SLOWLY INTENSIFY TO
50 KNOTS AT TAU 72. NEAR TAU 96, TC 08S IS FORECAST TO RECURVE
ALONG THE WESTERN PERIPHERY OF THE STR BUT WILL GRADUALLY
TRANSITION TO A SUBTROPICAL LOW AND WEAKEN AS IT TRACKS OVER COOL 
SST (23-25C) AND ENCOUNTERS STRONG VERTICAL WIND SHEAR (30-40 KNOTS) 
ASSOCIATED WITH STRONG UPPER-LEVEL WESTERLIES.            

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH TAU 72 WITH A 105NM SPREAD IN SOLUTIONS AT TAU 72
THUS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST THROUGH TAU 72.
AFTER TAU 72, THERE ARE SIGNIFICANT DIFFERENCES IN TRACK SPEED WITH
GREATER ALONG-TRACK SPREAD THUS MEDIUM CONFIDENCE. INTENSITY
GUIDANCE IS IN OVERALL GOOD AGREEMENT THROUGH THE FORECAST PERIOD
WITH THE JTWC INTENSITY FORECAST SLIGHTLY ABOVE THE JTWC INTENSITY
CONSENSUS (ICNW) CLOSER TO THE HWRF INTENSITY FORECAST.         

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