Ciclone tropicale Robyn attivo nell'oceano Indiano meridionaleREMARKS:052100Z POSITION NEAR 16.2S 92.1E.
TROPICAL CYCLONE (TC) 23S (ROBYN), LOCATED APPROXIMATELY 365 NM
SOUTHWEST OF THE COCOS ISLANDS, HAS TRACKED EASTWARD AT 01 KNOT OVER
THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS WANING
DEEP CONVECTION THAT IS BECOMING MORE DISORGANIZED DUE TO 20-30
KNOTS OF NORTHWESTERLY VERTICAL WIND SHEAR. ACCORDINGLY, DVORAK
ESTIMATES FROM PGTW, KNES, AND APRF HAVE DROPPED OVER THE LAST 12
HOURS AND NOW RANGE FROM 30 TO 55 KNOTS. THE CURRENT POSITION IS
BASED ON A 051854Z AMSU MICROWAVE IMAGE WHICH SUGGESTS THE LOW LEVEL
CIRCULATION CENTER (LLCC) IS EXPOSED AND LOCATED TO THE NORTHWEST OF
THE MAIN CONVECTION. AS TC 23S WEAKENS, IT HAS SLOWED IN FORWARD
TRACK SPEED DUE TO COMPETING STEERING INFLUENCES AT THE LOW TO MID
LEVELS. OVER THE NEXT 12 HOURS, TC ROBYN IS EXPECTED TO CONTINUE
WEAKENING AS IT LOSES POLEWARD OUTFLOW (PREVIOUSLY ENHANCED BY A
PASSING MID-LATITUDE TROUGH) AND START TRACKING WESTWARD UNDER THE
INFLUENCE OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE BUILDING IN FROM
THE WEST. BY TAU 36, THE SYSTEM IS EXPECTED TO DISSIPATE AS A
SIGNIFICANT TROPICAL CYCLONE AS IT SUCCUMBS TO EXCESSIVE VERTICAL
WIND SHEAR AND LACK OF A VENTING MECHANISM. THE NUMERICAL MODEL AIDS
ARE IN GOOD AGREEMENT WITH A WESTWARD TRACK AND THIS FORECAST IS
SLOWER THAN THE JTWC CONSENSUS IN ORDER TO REFLECT UNCERTAINTY IN
TRACK SPEED OVER THE NEXT 06 HOURS AS THE SYSTEM MAKES ITS TURN TO
THE WEST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 051800Z IS 18 FEET.
NEXT WARNINGS AT 060900Z AND 062100Z.//
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Immagini satellitariIRWater Vapor