WDXS31 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (BATSIRAI) 
WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.7S 63.2E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 428 NM NORTHEAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE 
SYSTEM HAS EXPANDED AND BECOME LESS SYMMETRICAL AS FEEDER BANDS HAVE 
BEGUN TO UNRAVEL. A RAGGED 10-NM PINHOLE EYE HAS ALSO BECOME CLOUD-
FILLED. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED 
ON A DIMPLE FEATURE (CLOUD-FILLED EYE). THE INITIAL INTENSITY OF 
85KTS IS PLACED WITH MEDIUM CONFIDENCE BASED ON OVERALL ASSESSMENT 
OF AGENCY AND AUTOMATED DVORAK ESTIMATES (SEE BELOW) AND REFLECTS 
THE 6-HR CONVECTIVE DECLINE. ANALYSIS INDICATES A MARGINALLY 
FAVORABLE ENVIRONMENT WITH STRONG WESTWARD AND POLEWARD OUTFLOW AND 
WARM ALONG-TRACK SST IN THE SOUTH INDIAN OCEAN OFFSET BY MODERATE TO
STRONG (20-25KT) VWS. THE CYCLONE IS TRACKING ALONG THE NORTHEASTERN 
PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE SOUTHWEST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: NORTHEASTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE SOUTHWEST.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   CIMSS SATCON: 62 KTS AT 310948Z
   CIMSS ADT: 67 KTS AT 311215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 BATSIRAI WILL COMMENCE ON A SOUTHWESTWARD
TRACK  AS THE STR IS WEAKENED BY A TRANSITORY MID-LATITUDE TROUGH.
AFTER THE TROUGH RECEDES AFTER TAU 48, THE STR WILL SLIGHTLY
REBUILD AND DRIVE THE CYCLONE ON A MORE WESTWARD THEN
WEST-SOUTHWESTWARD TRAJECTORY TOWARD CENTRAL MADAGSCAR. THE
MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A SLOW INTENSIFICATION
TO A PEAK OF 105KTS BY TAU 96. AFTERWARD, VWS INCREASE AND LAND
INTERACTION WITH THE APPROACH INTO MADAGASCAR WILL WEAKEN THE
SYSTEM DOWN TO 90KTS BY TAU 120 PRIOR TO LANDFALL.  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH A GRADUAL AND EVEN SPREAD TO 150NM AT TAU 120, LENDING MEDIUM
CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS LAID CLOSE TO THE
MODEL CONSENSUS. THERE IS ALSO MEDIUM CONFIDENCE TO THE INTENSITY
FORECAST UP TO TAU 72; AFTERWARD, LOW CONFIDENCE DUE TO THE
INCREASING VWS AND LAND INTERACTION.

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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