WDXS31 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (BELAL) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.5S 54.5E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 45 NM WEST OF ST DENIS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLIGHT
INCREASING INFLUENCE FROM THE WESTERLIES ACROSS SOUTHERN
MADAGASCAR, WRAPPING A SMALL INJECTION OF DRY AIR AROUND THE
NORTHWESTERN PERIPHERY OF THE SYSTEM, MAINTAINING THE CURRENT 
INTENSITY WITH NO OBSERVABLE SIGNIFICANT DEVELOPMENT. WITH THE
INCREASED INFLUENCE OF THE WESTERLIES AND MID-LATITUDE TROF 
AS 05S HAS MADE ITS SOUTHEASTERLY TURN TOWARD LA REUNION, UPPER-LEVEL 
OUTFLOW HAS BEEN LIMITED TO AN EASTWARD COMPONENT ALONG THE SOUTHERN 
SEMICIRCLE. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS 
AN OBSCURED PINHOLE EYE BY THE TIGHTLY WRAPPED CONVECTIVE STRUCTURES
AROUND THE MAXIMUM TURNING. BELOW THE CONTINUING AND OBSCURING
CYCLONICALLY WRAPPED UPPER-LEVEL CLOUD FEATURES, A PARTIAL 142328Z
SSMIS 37 GHZ MICROWAVE IMAGE REVEALS A LOW-LEVEL AND DEFINED EYE
FEATURE. THE INITIAL POSITION IS PLACED IN HIGH CONFIDENCE BASED ON
THE SOUTHEASTWARD MOVING CYCLONE INDICATED ON THE 141837Z ASCAT
IMAGERY, A PREVIOUSLY OBSERVED PINHOLE EYE ON ANIMATED EIR IMAGERY,
AND THE AFOREMENTIONED 142328Z MICROWAVE IMAGERY. THE INITIAL
INTENSITY OF 90 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
DVORAK INTENSITY ESTIMATES RANGING FROM 77 TO 90 KNOTS, AS WELL AS
AN OBSERVED SLIGHT DECREASE IN WRAPPED CONVECTIVE FEATURES AROUND
THE WESTERN PERIPHERY OF THE STORM.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T5.0 - 90 KTS
   CIMSS ADT: 57 KTS AT 142100Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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: TC 05S IS TRACKING SOUTHEASTWARD TOWARD LA
REUNION AND FORECAST TO TURN GENERALLY EAST-SOUTHEASTWARD
THROUGHOUT THE FORECAST PERIOD AS THE DEEP-LAYERED SUBTROPICAL RIDGE 
(STR) WILL CONTINUE TO STRONGLY INFLUENCE THE MOVEMENT OF THE STORM 
UNTIL TAU 96. THE SYSTEM IS NOT EXPECTED TO UNDERGO WEAKENING THROUGH 
TAU 24, BUT IS EXPECTED TO MAINTAIN AN INTENSITY OF 90 KTS UNDER 
FAVORABLE ENVIRONMENTAL CONDITIONS. BY TAU 36, DRY AIR WILL SLOWLY 
WRAP CYCLONICALLY AROUND TC 05S FROM THE WESTERN PERIPHERY. AS
THE CYCLONE CONTINUES TO THE SOUTHEAST AND THEN THE EAST-SOUTHEAST, A 
SLOW AND STEADY WEAKENING IS FORECAST UNTIL TAU 72 DUE TO INCREASING
VERTICAL WIND SHEAR (VWS) AND DRY AIR ENTRAINMENT. AFTER TAU 72, TC
05S IS EXPECTED TO SLOW SIGNIFICANTLY AND BECOME QUASI-STATIONARY WITH 
THE WELL-ESTABLISHED STR TO THE WEST AND EAST.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN CLOSE
AGREEMENT THROUGH TAU 48 WITH A 45 NM CROSS-TRACK SPREAD. FOLLOWING
TAU 48, CROSS-TRACK SPREAD DIVERGES MODERATELY TO SIGNIFICANTLY OF
UP TO 100 NM AS COMPETING STEERING FLOWS ENHANCE LATER IN THE
FORECAST PERIOD. AFTER TAU 72, DETERMINISTIC AND PROBABILISTIC
GUIDANCE DIVERGES SIGNIFICANTLY WITH UNCERTAINTY IN AN ACCURATE
CONSENSUS. INTENSITY GUIDANCE MAINTAINS CLOSE AGREEMENT THROUGH TAU
72 AS WELL, WITH A SUSTAINED INTENSITY OF 85-90 KTS THROUGH TAU
24, AND STEADILY DECREASING AS TC 05S TRACKS GENERALLY TO THE
SOUTHEAST.

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