WDXS31 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY)     
WARNING NR 037//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.8S 53.0E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 136 NM WEST-NORTHWEST OF ST DENIS
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 19 KTS
   SIGNIFICANT WAVE HEIGHT: 44 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
SIGNIFICANT WEAKENING ASSOCIATED WITH AN ONGOING EYEWALL REPLACEMENT
CYCLE (ERC) WITH THE CONVECTIVE STRUCTURE BECOMING MORE ASYMMETRIC
OVER THE PAST 12 HOURS. A 202140Z AMSR2 89GHZ MICROWAVE IMAGE
REVEALS A MOAT SURROUNDING A DETERIORATING INNER EYEWALL,
ESPECIALLY OVER THE SOUTHEAST QUADRANT, WITH A DEVELOPING OUTER
EYEWALL. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH RADIAL
OUTFLOW AND LOW VERTICAL WIND SHEAR, HOWEVER, TROPICAL CYCLONE (TC)
11S IS TRACKING QUICKLY WEST-SOUTHWESTWARD AT 19 KNOTS ALONG A
STRONG SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTH. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EIR (EWS-G1).
THE INITIAL INTENSITY OF 110 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE SUBJECTIVE DVORAK ESTIMATES. ADT AND AIDT OBJECTIVE
ESTIMATES ARE SLIGHTLY LOWER AT 102 AND 106 KNOTS, RESPECTIVELY,
AND ARE TRENDING LOWER.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED STR POSITIONED TO THE
SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   FMEE: T5.5 - 102 KTS
   CIMSS SATCON: 122 KTS AT 202131Z
   CIMSS ADT: 102 KTS AT 210000Z

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

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: DUE TO FAVORABLE UPPER-LEVEL CONDITIONS, TC
11S COULD COMPLETE ERC AND REINTENSIFY SLIGHTLY OR MAINTAIN INTENSITY 
PRIOR TO MAKING LANDFALL WITHIN THE NEXT 12 HOURS. NEAR TAU 12, TC 11S 
WILL WEAKEN QUICKLY AS IT APPROACHES EASTERN MADAGASCAR BUT COULD 
WEAKEN MORE QUICKLY WITH A PROLONGED ERC. FROM TAU 12 TO TAU 36, THE 
SYSTEM WILL WEAKEN RAPIDLY AS IT CROSSES MADAGASCAR'S MOUNTAINOUS 
TERRAIN. AFTER TAU 36, 11S WILL REEMERGE OVER THE MOZAMBIQUE CHANNEL 
AND TURN ONTO A MORE WESTWARD TRACK AS IT TRANSITIONS TO A SUBTROPICAL 
STEERING RIDGE OVER SOUTHERN AFRICA. TC 11S IS EXPECTED TO REINTENSIFY 
TO 65 KNOTS BY TAU 72 PRIOR TO MAKING LANDFALL OVER THE EAST COAST OF 
MOZAMBIQUE. AFTER TAU 72, THE SYSTEM WILL TRACK INLAND AND RAPIDLY 
WEAKEN WITH DISSIPATION EXPECTED BY TAU 120. HOWEVER, THE SYSTEM IS 
EXPECTED TO BRING HEAVY RAINFALL OVER MOZAMBIQUE AS IT SLOWS INLAND. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT WITH AN 80NM TO 110NM CROSS-TRACK SPREAD IN SOLUTIONS FROM
TAU 48 TO TAU 72. AFTER TAU 72, THERE IS INCREASING UNCERTAINTY ON
THE EXACT TRACK OF THE REMNANTS OVER LAND. RELIABLE INTENSITY
GUIDANCE IS IN TIGHT AGREEMENT INDICATING A RAPIDLY WEAKENING SYSTEM
THROUGH TAU 36. AFTER TAU 36, INTENSITY GUIDANCE GENERALLY SUPPORTS
THE REINTENSIFICATION PHASE WITH PEAK INTENSITY REFLECTED IN HWRF
AND COAMPS-TC (NAVGEM VERSION) TO 65 TO 75 KNOTS BY TAU 72. THE
201800Z COAMPS-TC ENSEMBLE INDICATES RAPID INTENSIFICATION
PROBABILITIES INCREASING TO 40 TO 50 PERCENT NEAR TAU 72 SUPPORTING
THE JTWC INTENSITY FORECAST.

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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