WDXS31 PGTW 310300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (ELEVEN)       
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.1S 67.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 619 NM EAST-NORTHEAST OF PORT LOUIS,
                         MAURITIUS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 11S CONTINUES TO STRUGGLE UNDER MARGINAL
ENVIRONMENTAL CONDITIONS INCLUDING HIGH VERTICAL WIND SHEAR (VWS)
AND DRY AIR ENTRAINMENT. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS AN EXPOSED, DEFINED LOW-LEVEL CIRCULATION, WITH
DEEP CONVECTION SHEARED OVER THE WESTERN QUADRANT. A 302259Z SSMIS
37GHZ COLOR COMPOSITE MICROWAVE IMAGE, HOWEVER, REVEALS SHALLOW
BANDING WRAPPING TIGHTLY INTO A BROAD CENTER. THEREFORE, THE INITIAL 
INTENSITY HAS BEEN HELD AT 35 KNOTS, WITH SUBJECTIVE DVORAK ESTIMATES 
RANGING FROM 30-35 KNOTS. CIMSS OBJECTIVE INTENSITY ESTIMATES RANGE 
FROM 28-44 KNOTS. THE INITIAL POSITION IS PLACED WITH MEDIUM 
CONFIDENCE BASED ON THE EIR IMAGERY AND THE SSMIS IMAGE. 

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: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T2.5 - 35 KTS
   FMEE: T2.0 - 30 KTS
   CIMSS SATCON: 44 KTS AT 302300Z
   CIMSS ADT: 28 KTS AT 310000Z
   CIMSS AIDT: 37 KTS AT 310000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 11S IS EXPECTED TO TRACK WESTWARD THROUGH
TAU 24 ALONG THE NORTHERN PERIPHERY OF THE STR. AFTER TAU 24, AN
APPROACHING UPPER-LEVEL TROUGH WILL WEAKEN THE STR ALLOWING THE
SYSTEM TO TURN WEST-SOUTHWESTWARD THROUGH TAU 48 TOWARD A BREAK IN
THE STR. DURING THIS PORTION OF THE FORECAST TRACK, THE SYSTEM WILL
CONTINUE TO STRUGGLE UNDER MODERATE TO HIGH (20-25 KNOTS) VERTICAL
WIND SHEAR AND DRY AIR ENTRAINMENT. ALTHOUGH THE SYSTEM SHOULD
MAINTAIN GALE-FORCE WINDS OVER THE SOUTHERN SEMICIRCLE, THERE IS A
GOOD POSSIBILITY THE SYSTEM COULD SIGNIFICANTLY WEAKEN BELOW 30
KNOTS. AFTER TAU 48, HOWEVER, THE TROUGH IS FORECAST TO FILL, WITH
THE STR RE-BUILDING TO THE SOUTH. THIS WILL DRIVE THE SYSTEM ON A
MORE WESTWARD TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD.
THE SYSTEM IS LIKELY TO RE-INTENSIFY AFTER TAU 72 AS ENVIRONMENTAL
CONDITIONS SLOWLY IMPROVE, WITH DECREASING VWS AND A MOISTENING
CORE. ADDITIONALLY, EQUATORWARD OUTFLOW SHOULD IMPROVE AS THE
SYSTEM APPROACHES MADAGASCAR. THIS WILL ALLOW THE SYSTEM TO
INTENSIFY TO ABOUT 50 KNOTS PRIOR TO LANDFALL NEAR TAU 108. 

MODEL DISCUSSION: WITH THE EXCEPTION OF THE UK-MET (EGRR) AND THE
UK-MET ENSEMBLE MEAN (UEMN), WHICH TRACK THE SYSTEM SOUTHWESTWARD
INTO THE STR OVER MAURITIUS, THE MAJORITY OF THE DETERMINISTIC 
GUIDANCE HAS SHIFTED TO A STRAIGHT-RUNNER PATTERN. THE VAST MAJORITY 
OF THE GEFS AND EPS SOLUTIONS ALSO SUPPORT THE WESTWARD TRACK 
SCENARIO. RELIABLE INTENSITY GUIDANCE SUPPORTS THE LIKELY RE-
INTENSIFICATION PHASE AFTER TAU 72, WITH PEAK INTENSITIES RANGING 
FROM 40 TO 55 KNOTS.   

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