ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM SUBTROPICAL STORM ANA DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT MON APR 21 2003 ANA LOOKED RATHER TROPICAL THIS EVENING...WITH TROPICAL SATELLITE INTENSITY ESTIMATES OF 35 KT FROM SAB AND TAFB. SSM/I AND TRMM OVERPASSES NEAR 2330Z EVEN SUGGESTED AN EYE MIGHT BE FORMING. HOWEVER...SINCE 00Z THE CONVECTION HAS BECOME LESS ORGANIZED. ADDITIONALLY...AN AMSU OVERPASS AT 2200Z DID NOT SHOW A WARM CORE. WHILE THIS IS NOT TOTALLY CONCLUSIVE...AS THE AMSU INSTRUMENT MAY NOT FULLY RESOLVE A WARM CORE IN A COMPACT SYSTEM LIKE ANA...IT WILL REMAIN A SUBTROPICAL STORM FOR NOW. MAXIMUM WINDS REMAIN 35 KT BASED ON THE SATELLITE ESTIMATES AND A 33-KT 1003-MB SHIP SOUTH OF THE CENTER. IT SHOULD BE NOTED THAT QUIKSCAT DATA SUGGESTS THAT ANA COULD BE A LITTLE STRONGER THAN 35 KT. THE INITIAL MOTION IS 100/15...AND THE SHORT-TERM MOTION IS CLOSER TO 090/15. ANA REMAINS EMBEDDED DEEP-LAYER WESTERLY FLOW SOUTH OF A CYCLONE NEAR 38N60W. THIS SHOULD MOVE THE SYSTEM EASTWARD FOR 12 HR OR SO WITH A MORE EAST-NORTHEASTWARD MOTION THEREAFTER. ALL GUIDANCE AGREES WITH THIS SCENARIO...AS DOES THE OFFICIAL FORECAST WHICH IS BASICALLY A SLIGHTLY FASTER UPDATE OF THE PREVIOUS PACKAGE. AFTER 48 HR A FRONTAL SYSTEM COMING FROM THE NORTH MAY TURN ANA BACK TO AN EASTWARD MOTION...WHICH IS NOTED IN THE FORECAST TRACK. VERTICAL SHEAR PRODUCTS FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE 30 KT OF SHEAR OVER ANA. THIS HAS NOT YET SERIOUSLY IMPACTED THE CYCLONE...BUT INCREASING SHEAR FORECAST BY ALL LARGE-SCALE MODELS SHOULD CAUSE WEAKENING AFTER 12-24 HR. THE INTENSITY FORECAST CALLS FOR A SLOW WEAKENING UNTIL THE CYCLONE IS DISSIPATING IN 72 HR...BUT ANA COULD DISSIPATE EARLIER. THERE IS A CHANCE THAT INSTEAD OF DISSIPATING THE SYSTEM COULD CONTINUE EASTWARD AS A EXTRATROPICAL WAVE ALONG THE ABOVE-MENTIONED FRONTAL SYSTEM. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 22/0300Z 29.4N 60.5W 35 KTS 12HR VT 22/1200Z 29.4N 58.0W 35 KTS 24HR VT 23/0000Z 29.9N 54.2W 30 KTS 36HR VT 23/1200Z 30.7N 50.4W 30 KTS 48HR VT 24/0000Z 31.4N 46.5W 25 KTS 72HR VT 25/0000Z 32.0N 40.0W 25 KTS...DISSIPATING NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:55 UTC