ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM AGATHA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 AM PDT SUN MAY 23 2004 AGATHA IS BEGINNING TO DECAY. THE CENTRAL RING OF CONVECTION PRESENT IN MICROWAVE IMAGERY 12 HOURS AGO HAS BROKEN UP. NOTWITHSTANDING THE RECENT FLARE-UP IN THE SOUTHWEST QUADRANT... INFRARED IMAGERY INDICATES THAT THE AREAL EXTENT OF DEEP CONVECTION IS DECREASING. USING AN AVERAGE OF THE T AND CI NUMBERS...WHICH IS USUALLY A MORE ACCURATE INDICATOR THAN THE CI NUMBER FOR WEAKENING SYSTEMS...YIELDS AN INTENSITY ESTIMATE OF 40 KT. A QUIKSCAT PASS AT 01Z SUGGESTS THAT THE RADIUS OF 34 KT WINDS IS ALSO DECREASING. UNFORTUNATELY THE MOST RECENT PASS MISSED THE CYCLONE. THE INITIAL MOTION ESTIMATE IS 335/5. MODEL GUIDANCE CONTINUES TO INDICATE A WEAKENING OF THE STEERING CURRENTS OVER THE NEXT 24-48 HOURS. THE GFS SHOWS THE UPPER PORTION OF THE SYSTEM CONTINUING NORTHWARD AHEAD OF THE LARGE-SCALE UPPER TROUGH TO THE WEST OF AGATHA...WITH THE LOW LEVEL REMNANTS MOVING SLOWLY NORTHWESTWARD. THE NOGAPS AND THE UKMET MAINTAIN A MORE VERTICALLY COHERENT SYSTEM ON A TRACK TO THE RIGHT OF THE GFS. SINCE THE CYCLONE ALREADY APPEARS TO BE SHEARING OFF A BIT...THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO THE LEFT OF THE PREVIOUS ADVISORY...IN THE DIRECTION OF THE GFS AND THE SHALLOW BAM BUT WITH A SLOWER FORWARD SPEED. AGATHA IS OVER 26C SSTS AND HEADED...ALBEIT SLOWLY...FOR COOLER WATERS AND A MORE STABLE AIR MASS. A GRADUAL SPINDOWN IS THEREFORE EXPECTED. THE OFFICIAL INTENSITY FORECAST IS ADJUSTED DOWNWARD BUT IS STILL ABOVE THE SHIPS AND GFDL GUIDANCE. AGATHA IS EXPECTED TO DEGENERATE TO A NON-CONVECTIVE REMNANT LOW WITHIN 48-72 HOURS. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 23/1500Z 18.1N 110.4W 40 KT 12HR VT 24/0000Z 18.9N 110.6W 35 KT 24HR VT 24/1200Z 19.5N 110.8W 30 KT 36HR VT 25/0000Z 19.8N 110.9W 30 KT 48HR VT 25/1200Z 20.0N 111.0W 25 KT...DISSIPATING 72HR VT 26/1200Z 20.0N 111.0W 25 KT...REMNANT LOW 96HR VT 27/1200Z 20.5N 111.5W 25 KT...REMNANT LOW 120HR VT 28/1200Z 21.0N 112.0W 20 KT...REMNANT LOW $$ NNNN
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Page last modified: Friday, 02-Jul-2004 17:31:57 UTC