WDXS31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FAIDA) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.2S 51.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 216 NM EAST OF ANTANANARIVO, MADAGASCAR
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
OVER THE LAST SIX HOURS, DRY AIR AND HIGH VERTICAL WIND SHEAR
(15-20KTS) PUNCTURED THE VORTEX AT THE MID-LEVELS, RESULTING IN A
FULLY EXPOSED CIRCULATION DEPICTED ON ANIMATED ENHANCED INFRARED
IMAGERY (EIR). SYNOPTIC OBSERVATIONS ON SAINTE MARIE, MADAGASCAR
INDICATE WINDS TO WEST-SOUTHWEST AND CORROBORATES THE POSITIONING.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED LLCC
IDENTIFIED IN THE AFOREMENTIONED ANIMATED EIR. IBO THE AGENCY AND
OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF AN EXTENSION OF A
SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTHWEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   FMEE: T2.5 - 35 KTS
   CIMSS SATCON: 52 KTS AT 031550Z
   CIMSS ADT: 55 KTS AT 031800Z
   CIMSS AIDT: 44 KTS AT 031900Z
   CIMSS D-PRINT: 33 KTS AT 031900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TROPICAL CYCLONE (TC) 11S HAS BEEN
RELOCATED 120NM SOUTH OF PREVIOUS POSITION.

FORECAST DISCUSSION: TC 11S WILL TRACK WESTWARD FOR THE NEXT 24
HOURS BEFORE PASSING OVER LAND BETWEEN TAU 24-72. WHILE OVER LAND,
THE TRACK WILL CURVE SOUTHWESTWARD BETWEEN TAU 48-72 DRIVEN BY
LOW-LEVEL FLOW. WHEN THE SYSTEM RE-EMERGES OVER WATER, THE STEERING
INFLUENCE WILL BE A DEEP-LAYER RIDGE EXTENDING FROM LAND OVER THE
MOZAMBIQUE CHANNEL. THE SYSTEM WILL WEAKEN OVER THE NEXT 24 HOURS
DUE TO UPWELLING AND MODERATE TO HIGH VERTICAL WIND SHEAR. DRY AIR
ENTRAINMENT AND TOPOGRAPHIC INTERACTION WITH LAND BETWEEN TAU 24-72
WILL CAUSE THE STORM TO DISSIPATE BEFORE PASSING BACK OUT OVER
WATER. AT TAU 72 WHEN THE SYSTEM RE-EMERGES, THE ENVIRONMENT WILL
BE FAVORABLE FOR REDEVELOPMENT IN A MOIST ENVIRONMENT WITH LOW TO
MODERATE VERTICAL WIND SHEAR, MODERATE UPPER-LEVEL DIVERGENCE, AND
WARM SEA SURFACE TEMPERATURES ABOVE 26C.
THE REPOSITIONING OF 11S HAS SIGNIFICANTLY INFLUENCED THE FORECAST
TRACK FARTHER SOUTH THAN WAS REPRESENTED IN PREVIOUS FORECASTS.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS SPREAD OVER THE
FIRST 72 HOURS OF THE FORECAST DUE TO LIMITED ABILITY TO TRACK THE
WEAK VORTEX OVER LAND. THE MAXIMUM TRACK SPREAD IS 260NM BY TAU 36,
BUT CLOSES BELOW 100NM AFTER THE SYSTEM REEMERGES OVER WATER. THE
INTENSITY GUIDANCE IS IN MODERATELY GOOD AGREEMENT THAT THE SYSTEM
WILL WEAKEN BELOW WARNING THRESHOLD AND THEN REINTENSIFY OVER
WATER. 

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