WDXS31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (BELAL) 
WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.9S 65.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 515 NM EAST-SOUTHEAST OF PORT LOUIS,
                         MAURITIUS
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY 
EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH DEEP CONVECTION BEGINNING TO 
SHEAR TO THE EAST AND BECOME LESS ORGANIZED. AN 181210Z GMI 37 GHZ 
MICROWAVE IMAGE REVEALS SHALLOW BANDING WRAPPING INTO A WELL-DEFINED 
CENTER, WITH LIMITED DEEP CONVECTIVE BANDING OVER THE EASTERN 
QUADRANT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED 
ON THE GMI MICROWAVE IMAGE. UPPER-LEVEL CONDITIONS ARE MARGINALLY 
UNFAVORABLE DUE TO WEST-SOUTHWESTERLY UPPER-LEVEL WINDS AND 
ASSOCIATED MODERATE TO HIGH VERTICAL WIND SHEAR. HOWEVER, STRONG 
POLEWARD OUTFLOW IS FUELING DEEP CONVECTIVE BURSTS OVER THE EASTERN 
SEMICIRCLE. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON THE KNES SUBJECTIVE DVORAK ESTIMATE AND CIMSS 
OBJECTIVE ESTIMATES RANGING FROM 42-47 KTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW TO MID-LEVEL SUBTROPICAL RIDGE
(STR) POSITIONED TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS ADT: 47 KTS AT 180900Z
   CIMSS AIDT: 42 KTS AT 181230Z
   CIMSS DPRINT: 47 KTS AT 181300Z
   CIMSS DMINT: 42 KTS AT 181119Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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: TROPICAL CYCLONE (TC) 05S IS EXPECTED TO TRACK 
WESTWARD ALONG THE NORTHERN PERIPHERY OF THE STR TO THE SOUTH UNTIL 
AROUND TAU 24. AFTER TAU 24, O5S WILL TURN SOUTHWESTWARD AS THE RIDGE 
REORIENTS DUE TO AN APPROACHING SHORTWAVE TROUGH. IN ADDITION TO 
PERSISTENT VERTICAL WIND SHEAR, THE SYSTEM IS EXPECTED TO WEAKEN 
STEADILY AS DRY AIR ENVELOPS THE SYSTEM. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH 
A 65 NM CROSS-TRACK SPREAD AT TAU 36. THE 180000Z ECMWF AND GFS 
ENSEMBLES SUPPORT THE JTWC FORECAST TRACK WITH HIGH CONFIDENCE. THE 
JTWC INTENSITY FORECAST IS SUPPORTED BY THE COAMPS-TC AND HAFS-A 
GUIDANCE. 

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