WDXS31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 17S (FILIPO) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.6S 35.8E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 264 NM WEST-NORTHWEST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 17S (FILIPO) INTENSIFYING AND BECOMING MORE ORGANIZED
IN THE UPPER LEVELS AS IT APPROACHES THE EASTERN COAST OF
MOZAMBIQUE AS IT IS CURRENTLY STEERED ON THE NORTHERN PERIPHERY OF
A SUBTROPICAL RIDGE (STR) TO THE SOUTH. A 111234Z GMI 89GHZ
MICROWAVE PASS REVEALED A WELL-DEFINED MICROWAVE EYE FEATURE,
THOUGH THE LOWER-LEVEL STRUCTURE AS REVEALED IN THE 37GHZ BAND IS
LESS ORGANIZED. THE SYSTEM IS CURRENTLY IN A FAVORABLE REGION OF
LOW SHEAR (15-20KTS), WARM SEA SURFACE TEMPERATURES (29KTS), AND
GOOD POLEWARD AND EASTWARD OUTFLOW THAT EVENTUALLY TURNS
EQUATORWARD TOWARDS MADAGASCAR. THE INITIAL POSITION WAS BASED ON
AN EXTRAPOLATION FROM A 111430Z COWVR 33GHZ MICROWAVE IMAGE SHOWING
A BROAD LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL INTENSITY
WAS DETERMINED USING AGENCY AND OBJECTIVE FIXES LISTED BELOW,
HEDGED TOWARDS THE HIGHER END OF THE OBJECTIVE INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE NORTHERN PERIPHERY OF A STR TO THE
SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS SATCON: 61 KTS AT 1400Z
   CIMSS ADT: 47 KTS AT 111500Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 17S (FILIPO) IS FORECAST TO CONTINUE TO
TRACK TOWARDS THE EAST COAST OF MOZAMBIQUE OVER THE NEXT FEW HOURS,
MAKING LANDFALL BY TAU 12.  WHILE OVER LAND, THE SYSTEM IS EXPECTED
TO ROUND THE PERIPHERY OF AN STR OVER THE SOUTHERN MOZAMBIQUE
CHANNEL BEFORE COMING BACK OUT OVER LAND AROUND TAU 36. TC FILIPO
WILL CONTINUE TO TRACK SOUTHEAST WHILE UNDERGOING A BRIEF PERIOD OF
SUBTROPICAL TRANSITION (STT) BETWEEN TAU 16 AND 18 BEFORE
INTERACTING WITH A STRONG JET MAXIMUM TO THE SOUTH. BY TAU 72, THE
SYSTEM IS EXPECTED TO UNDERGO EXTRATROPICAL TRANSITION (ETT) BEFORE
BECOMING ENTIRELY EXTRATROPICAL NO LATER THAN TAU 96, BUT MORE
LIKELY CLOSER TO TAU 72. IN TERMS OF THE INTENSITY FORECAST,
CONDITIONS REMAIN FAVORABLE IN THE SHORT TIME BEFORE LANDFALL, SO A
SMALL AMOUNT OF ADDITIONAL INTENSIFICATION IS POSSIBLE PRIOR TO
LANDFALL, WHICH IS NOT CAPTURED IN THE SPECIFIC FORECAST POINT.
AFTER LANDFALL, THE SYSTEM IS EXPECTED TO WEAKEN  OVER THE NEXT
12-36 HOURS DUE TO INTERACTION WITH TERRAIN. ONCE THE SYSTEM MOVES
BACK OVER WATER, IT IS EXPECTED TO QUICKLY RECONSOLIDATE AND 
REINTENSIFY. VERTICAL WIND SHEAR IS EXPECTED TO INCREASE
SIGNIFICANTLY BY TAU 48 AS THE SYSTEM BECOMES UNDER THE INFLUENCE
OF STRONGER WESTERLY FLOW, BUT THIS WILL BE OFFSET BY ROBUST
OUTFLOW INTO A 180 KNOT JET MAX TO THE SOUTH. AS A RESULT, THE
SYSTEM IS EXPECTED TO RAPIDLY INTENSIFY UP TO A PEAK OF AT LEAST
65KTS BEFORE EXPERIENCING SIGNIFICANT SHEAR ABOVE 50 KNOTS AFTER
TAU 72, WHICH WILL QUICKLY SHEAR THE SYSTEM APART AS IT UNDERGOES
ETT. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TC 17S WILL TRAVEL OVER LAND THROUGH THE NEXT 36 HOURS BEFORE
CURVING SOUTHEAST THROUGH THE END OF THE FORECAST PERIOD, AS IT
ROUNDS THE RIDGE WHICH SLIDES UNDERNEATH THE SYSTEM. MAXIMUM
CROSS-TRACK SPREAD IS 150 NM BY TAU 96. THE JTWC INTENSITY GUIDANCE
SHOWS A FAIRLY HIGH AMOUNT OF UNCERTAINTY, AS THE HWRF, COAMPS-TC,
AND HAFS ALL INDICATE A PEAK INTENSITY AT OR ABOVE 70 KTS BETWEEN
TAUS 60-72, SKEWING THE JTWC CONSENSUS A BIT HIGHER DURING THE SAME
PERIOD. ADDITIONALLY, THE GFS, ECMWF AND COAMPS-TC ENSEMBLES ALL
INDICATE A PERIOD OF RAPID INTENSIFICATION (RI) THROUGH TAU 72 AS
THE SYSTEM UNDERGOES ETT. 

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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