WDXS31 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 17S (FILIPO)
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.0S 33.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 451 NM WEST-SOUTHWEST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL 
CYCLONE (TC) 17S (FILIPO) TRACKING OFFSHORE NEAR MAPUTO, MOZAMBIQUE, 
AND RETURNING TO OPEN WATER OVER THE PAST 12 HOURS. A PARTIALLY 
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION 
RESTRICTED TO THE SOUTHERN SEMICIRCLE IS OBSERVED IN A 130600Z 
METEOSAT-9 SATELLITE VISIBLE IMAGE. ADDITIONALLY, ROBUST
POLEWARD OUTFLOW ALOFT IS OBSERVED CHARACTERIZED BY PROMINENT CIRRUS 
FILAMENTS IN THE SOUTHWESTERN SEMICIRCLE. ENVIRONMENTAL ANALYSIS 
INDICATES THAT 17S IS IN A FAVORABLE ENVIRONMENT FOR FURTHER 
INTENSIFICATION WITH THE AFOREMENTIONED ROBUST POLEWARD OUTFLOW 
ALOFT, LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR, AND WARM (27-
28 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH 
HIGH CONFIDENCE BASED ON ANIMATED MSI REVEALING AN OBSERVABLE LLCC. 
THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON 
OBJECTIVE DVORAK ESTIMATES LISTED BELOW AND RECENT SCATTEROMETRY 
DATA.

INITIAL WIND RADII BASIS: SCATTEROMETRY DATA

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   CIMSS ADT: 33 KTS AT 130600Z
   CIMSS AIDT: 38 KTS AT 130600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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 17S IS CURRENTLY TRACKING
SOUTH-SOUTHWESTWARD ALONG THE WESTERN PERIPHERY OF A STR TO THE
EAST. TC 17S IS FORECAST TO MAKE A SOUTHEASTWARD TURN WITHIN THE
NEXT 6 HOURS AS THE STR PROPAGATES EASTWARD. THE SYSTEM WILL
CONTINUE TRACKING ALONG WESTERN PERIPHERY OF THE STR AND INCREASE 
TRACK SPEED AS IT MAKES ITS WAY INTO THE BAROCLINIC ZONE AND 
INTERACTS WITH THE UPPER-LEVEL JET TO THE SOUTH. NEAR TAU 24, TC 17S 
IS FORECAST TO BEGIN SUBTROPICAL TRANSITION AND COMPLETE SUBTROPICAL 
TRANSITION BY TAU 36. AFTER A SUSTAINED SUBTROPICAL PERIOD (TAU 36 TO 
TAU 60) HAVING FEATURES OF BOTH TROPICAL AND EXTRATROPICAL SYSTEMS, 
THE SYSTEM IS FORECAST TO COMPLETE EXTRATROPICAL TRANSITION BY TAU 
72. THE FORECASTED RISE TO PEAK INTENSITY OF 65 KTS AT TAU 24 IS 
PRIMARILY DUE TO THE INCREASED OUTFLOW ALOFT CAUSED BY THE TC 
POSITION RELATIVE TO THE UPPER-LEVEL MIDLATITUDE JET. FOLLOWING A 
PERIOD OF INTENSIFICATION TO TAU 24, VWS IS ANTICIPATED TO SHARPLY 
RISE AND INITIATE AN INTENSITY DOWNTREND.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN EXCEPTIONAL
AGREEMENT WITH A MERE 50 NM CROSS-TRACK SPREAD AT TAU 48 AND A 90
NM CROSS-TRACK SPREAD AT TAU 72. AS SUCH, THE JTWC TRACK FORECAST
IS PLACED WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT WITH ALL GUIDANCE SUGGESTING AN INCREASE IN INTENSITY
THROUGH TAU 24 WITH A WEAKENING TREND AFTERWARD. PEAK INTENSITY
RANGES FROM 55 TO 75 KTS WITH COAMPS-TC (NAVGEM BASED) BEING AT THE
HIGH END AND STATISTICAL-DYNAMICAL (GFS BASED) AT THE LOW END. THE 
JTWC INTENSITY PEAK IS PLACED SLIGHTLY HIGHER THAN CONSENSUS AT 65 
KTS.

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