WDXS31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY)         
WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0S 79.5E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 628 NM SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 11S HAS WEAKENED OVER THE PAST 12 HOURS WITH
WARMING CLOUD TOP TEMPERATURES AND A COOLING EYE TEMPERATURE
EVIDENT IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY.
ADDITIONALLY, EIR IMAGERY DEPICTS A MORE OBLONG STRUCTURE TO BOTH
THE EYE AND SYSTEM WITH A BREAK IN THE EYEWALL OVER THE EASTERN
QUADRANT. A 161056Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE IMAGE
SHOWS A SYMMETRIC CORE WITH A SMALL 15NM DIAMETER MICROWAVE EYE
FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.
ANIMATED WATER VAPOR IMAGERY CONTINUES TO SHOW RADIAL OUTFLOW THUS
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE. BASED ON THE STEADY
WEAKENING TREND SINCE ABOUT 160000Z, DVORAK DATA-T ESTIMATES HAVE
DECREASED TO THE T5.5-T6.0 (102-115 KNOTS) RANGE, HOWEVER, THE
INITIAL INTENSITY IS HELD CLOSER TO THE PGTW, DEMS, FMEE CURRENT
INTENSITY ESTIMATES OF 6.5 (127 KNOTS). IN GENERAL, OBJECTIVE
ESTIMATES RANGE FROM 110-120 KNOTS TO INCLUDE SATCON, ADT, AIDT,
OPEN-AIIR AND DMN.

INITIAL WIND RADII BASIS: AMSR2 DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   DEMS: T6.5 - 127 KTS
   FMEE: T6.5 - 127 KTS
   CIMSS SATCON: 120 KTS AT 160815Z
   CIMSS ADT: 115 KTS AT 161200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 11S WILL TRACK WESTWARD THROUGH TAU 48
ALONG THE NORTHERN PERIPHERY OF THE STR. AFTER TAU 48, THE SYSTEM
WILL TURN WEST-SOUTHWESTWARD AS THE STR REORIENTS IN RESPONSE TO AN 
APPROACHING MAJOR SHORTWAVE TROUGH. TC 11S SHOULD WEAKEN STEADILY DUE 
TO DRY AIR ENTRAINMENT AND POSSIBLY COOL UPWELLING WATER THROUGH THE 
FORECAST PERIOD WITH A GRADUAL DECREASE TO 100 KNOTS BY TAU 120 AS 
THE SYSTEM APPROACHES THE EAST COAST OF MADAGASCAR.    

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72 WITH A 120NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU
72. AFTER TAU 72, THE CROSS-TRACK SPREAD WILL INCREASE TO 250NM BY
TAU 120 WITH INCREASING UNCERTAINTY IN THE EXACT FORECAST TRACK.
BOTH THE ECMWF (EPS) AND GFS (GEFS) ENSEMBLES INDICATE A HIGH
PROBABILITY OF LANDFALL OCCURRING OVER CENTRAL MADAGASCAR. THE
160000Z COAMPS-TC ENSEMBLE INDICATES RAPID INTENSIFICATION IS
UNLIKELY, HOWEVER, IT DOES SHOW A 40 PERCENT PROBABILITY OF
MODERATE INTENSIFICATION IN THE TAU 36 TO TAU 60 TIME PERIOD.
RELIABLE INTENSITY GUIDANCE SUPPORTS A STEADY WEAKENING TREND
THROUGH THE FORECAST PERIOD, HOWEVER, DECAY-SHIP (GFS VERSION) DOES
INDICATE A MODEST 10-KNOT INCREASE FROM 115 TO 125 KNOTS IN THAT
SAME TIME RANGE.      

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