WDXS32 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (GRANT) WARNING NR 
035//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9S 63.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 485 NM NORTHEAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 09S (GRANT) CONTINUES ITS BATTLE AGAINST DRY
AIR ENTRAINMENT WITH DEEP CONVECTION NOW RELEGATED TO THE
SOUTHWESTERN PORTION OF THE CIRCULATION WITH RAPIDLY WARMING CLOUD
TOP TEMPERATURES AS DEPICTED BY ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY. THE CURRENT ENVIRONMENT GIVES THE SYSTEM
MARGINAL CONDITIONS FOR FURTHER DEVELOPMENT WITH SEA SURFACE
TEMPERATURES AT 27 C TO 28 C, VERTICAL WIND SHEAR OF 10-15 KTS,
MODERATE EQUATORWARD OUTFLOW, OFFSET BY SIGNIFICANT DRY AIR
ENTRAINMENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON EIR IMAGERY AND AGENCY FIXES. THE INITIAL INTENSITY OF 35
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE OBJECTIVE AND
SUBJECTIVE AIDS LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS SATCON: 38 KTS AT 031030Z
   CIMSS ADT: 41 KTS AT 031230Z
   CIMSS AIDT: 36 KTS AT 031230Z
   CIMSS D-MINT: 27 KTS AT 030906Z
   CIMSS D-PRINT: 23 KTS AT 031230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: SUBSTANTIAL DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 09S WILL CONTINUE TO TRACK WEST
SOUTHWESTWARD WHILE OSCILLATING AROUND WARNING CRITERIA INTENSITY
UNTIL TAU 36. A SLIGHT DECREASE IN VERTICAL WIND SHEAR COULD ALLOW
MAXIMUM WINDS TO CLIMB BACK TO 40-45 KTS, THOUGH THE CURRENT
EFFECTS OF DRY AIR ENTRAINMENT ON THE STRUCTURE OF THE SYSTEM MAKE
THIS FORECASTED INCREASE QUESTIONABLE. STILL EQUALLY QUESTIONABLE
IS THE FORECASTED TRACK AND THE APPROACH TOWARD THE EASTERN COAST
OF MADAGASCAR. IF CURRENT CONDITIONS HOLD, DISSIPATION COULD TAKE
PLACE BEFORE TAU 96. EITHER WAY, TC 09S WILL CONTINUE TO BE WATCHED
AS IT MEANDERS WEST-SOUTHWESTWARD WITH ONLY SLIGHT VARIATIONS IN
STRENGTH AND CONVECTIVE ACTIVITY.

MODEL DISCUSSION: CROSS TRACK SPREAD AMONGST MODEL GUIDANCE
INCREASES UP TO 100 NM AT TAU 36 BUT THE MAJORITY OF THE GUIDANCE
IS IN AGREEMENT ON A GRADUAL WEST-SOUTHWESTWARD TRACK FOR THE
REMAINDER OF THE FORECAST PERIOD. THE ONLY OUTLIER AT THE MOMENT IS
NAVGEM, OFFERING A STRAIGHT WESTWARD TRACK SOLUTION. THE JTWC
FORECASTED TRACK IS PLACED CLOSE TO THE MULTI MODEL CONSENSUS WITH
HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT WITH A 15
KT SPREAD AND COAMPS-TC THE ONLY GUIDANCE STILL FORECASTING ANY
SIGNIFICANT INTENSIFICATION. THE JTWC FORECASTED INTENSITY REFLECTS
VALUES CLOSE TO THE MULTI MODEL CONSENSUS WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH
   INTENSITY 72-120 HR: HIGH//
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