WDXS31 PGTW 151500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (BELAL)       
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.3S 56.1E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 66 NM SOUTHEAST OF ST DENIS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AS INDICATED ON ANIMATED RADAR IMAGERY, TROPICAL CYCLONE (TC) 05S
TRACKED JUST NORTH OF LA REUNION NEAR 150600Z THEN DIPPED ABRUPTLY
SOUTHEASTWARD ALONG THE EAST COAST OF THE ISLAND. HOURLY SURFACE
OBSERVATIONS FROM SAINT DENIS (61980) INDICATED MAXIMUM SUSTAINED
WINDS OF 56 KNOTS (10-MINUTE AVERAGE) WITH A MINIMUM SEA LEVEL
PRESSURE VALUE OF 977.8 MB. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS RAPID WEAKENING OF CORE CONVECTION, WITH WARMING
CLOUD TOP TEMPERATURES. A 151200Z SSMIS 91 GHZ MICROWAVE IMAGE
REVEALS DEEP CONVECTIVE BANDING PRIMARILY OVER THE EASTERN
SEMICIRCLE DUE TO UPPER-LEVEL SUBTROPICAL WESTERLIES AND DRY AIR
ENTRAINMENT, WITH SHALLOW BANDING EXPOSED OVER THE WESTERN
SEMICIRCLE. CONSEQUENTLY, RECENT CIMSS OBJECTIVE ESTIMATES HAVE
DECREASED RAPIDLY AND NOW RANGE FROM 49 TO 57 KNOTS. SUBJECTIVE
DVORAK ESTIMATES DECREASED BUT REMAIN IN THE T4.0 TO T4.5 (65 TO 77
KNOTS) RANGE WITH CURRENT INTENSITY ESTIMATES RANGING FROM 4.5 TO
5.0 (77 TO 90 KNOTS). THE INITIAL INTENSITY IS ASSESSED AT 75 KNOTS
WITH MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED STEERING RIDGE ENTRENCHED
TO THE NORTH WITH AN EXTENSION OF THE RIDGE TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T5.0 - 90 KTS
   FIMP: T4.5 - 77 KTS
   CIMSS ADT: 57 KTS AT 151200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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 05S IS FORECAST TO TRACK EAST-SOUTHEASTWARD
TO EASTWARD THROUGH TAU 48 ALONG THE SOUTHERN PERIPHERY OF THE
AFOREMENTIONED STEERING RIDGE. HOWEVER, THE SYSTEM IS EXPECTED TO
SLOW SIGNIFICANTLY AFTER TAU 48 AS THE SUBTROPICAL RIDGE BUILDS
WEST AND EAST OF THE SYSTEM EFFECTIVELY BLOCKING EASTWARD
PROGRESSION AND PRODUCING A MORE ERRATIC, QUASI-STATIONARY TRACK
MOTION. IN GENERAL, TC 05S WILL WEAKEN STEADILY THROUGH THE
FORECAST PERIOD DUE TO DRY AIR ENTRAINMENT AND PERSISTENT VERTICAL
WIND SHEAR (20 TO 30 KNOTS).  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT ONLY 
THROUGH TAU 36 WITH A 45 NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 36. 
HOWEVER, DETERMINISTIC GUIDANCE DIVERGES QUICKLY AFTER TAU 36 WITH POOR 
AGREEMENT DUE TO THE COMPETING STEERING ENVIRONMENT. THE 150000Z ECMWF 
AND GFS ENSEMBLES (EPS AND GEFS) ALSO INDICATE HIGH UNCERTAINTY IN THE 
FORECAST TRACK THUS THERE IS LOW OVERALL CONFIDENCE IN THE JTWC 
FORECAST TRACK.  

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