281500Z POSITION NEAR 13.4S 57.9E. TROPICAL CYCLONE (TC) 13S (FELLENG) LOCATED APPROXIMATELY 500 NM NORTH-NORTHEAST OF LA REUNION, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS A TIGHTLY WRAPPED, IMPROVING SYSTEM WITH A SYMMETRIC CENTRAL DENSE OVERCAST FEATURE NOW OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). UPPER-LEVEL ANALYSIS INDICATES A FURTHER IMPROVING ENVIRONMENT AS A POINT-SOURCE ANTICYCLONE IS BEGINNING TO DEVELOP OVER THE LLCC GIVING WAY TO AMPLE EQUATORWARD OUTFLOW WHICH IS BEING ASSISTED BY AN UPPER-LEVEL LOW NEAR 20S 75E AND LOW TO MODERATE (5- 15 KNOTS) SOUTHERLY VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS BASED ON THE MSI IMAGERY AND SATELLITE POSITION FIXES FROM PGTW AND KNES. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS BASED ON CONGRUENT DVORAK INTENSITY ESTIMATES OF 45 KNOTS FROM BOTH PGTW AND KNES AND IS CONSISTENT WITH THE OVERALL IMPROVING STRUCTURE. TC 13S IS FORECAST TO TRACK WESTWARD UNDER THE STEERING INFLUENCE OF THE DEEP SUBTROPICAL RIDGE (STR) THROUGH TAU 36 BUT WILL THEN TURN POLEWARD AND TRACK ALONG THE WESTERN PERIPHERY OF THE STR, WHICH IS FORECAST TO RE-ORIENT NORTH-SOUTH, AS A DEEP MIDLATITUDE TROUGH PROPAGATES TOWARDS MADAGASCAR. DUE TO FAVORABLE ENVIRONMENTAL CONDITIONS, TC 13S IS EXPECTED TO INTENSIFY THROUGH THE FORECAST PERIOD TO A PEAK INTENSITY OF 75 KNOTS BY TAU 96. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 72 WITH ONLY SLIGHT DIFFERENCES IN THE TRACK AND TIMING OF THE POLEWARD TURN. AFTER TAU 72, NOGAPS AND GFDN SHOW THE STR REBUILDING BACK IN SOUTH OF THE SYSTEM GIVING TC 13S A WESTWARD BIAS TOWARDS MADAGASCAR. GFS AND ECMWF, HOWEVER, MAINTAIN THE NORTH-SOUTH ORIENTED STR ALLOWING FOR THE MORE POLEWARD TRACK. BASED ON THESE DIFFERENCES IN THE MODEL SOLUTIONS, THE JTWC FORECAST FAVORS THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 281200Z IS 15 FEET.
- JTWC + EUMETSAT
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