ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ALETTA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012006 800 PM PDT SUN MAY 28 2006 AS WAS THE CASE EARLIER TODAY...THE CENTER OF THE TROPICAL CYCLONE IS VERY DIFFICULT TO LOCATE USING GEOSYNCHRONOUS SATELLITE IMAGES. THE CURRENT POSITION IS BASED ON EXTRAPOLATION OF A SLOW NORTHWARD MOTION AND A FAIR CENTER FIX OFF OF A RECENT...0051 UTC... SSM/I IMAGE. THE INITIAL MOTION ESTIMATE REMAINS 360/2. DYNAMICAL MODELS ARE IN GENERAL AGREEMENT ABOUT A GRADUAL TURN TOWARD THE WEST DURING THE NEXT COUPLE OF DAYS. EVEN THE GFDL HAS BACKED OFF FROM ITS INSISTENT FORECAST OF A LANDFALL IN MEXICO...AND NOW SHOWS A TRACK PARALLEL TO THE COAST. A GRADUAL LEFT TURN IS ALSO CONSISTENT WITH THE GLOBAL MODELS FORECASTS SHOWING THE BUILDING OF A WEAK MID-LEVEL RIDGE ALONG ABOUT 20N LATITUDE BY 36-48 HOURS. THE CLOUD PATTERN IS QUITE POORLY ORGANIZED AT THE MOMENT. THERE ARE NO OBVIOUS BANDING FEATURES...AND DEEP CONVECTION HAS DIMINISHED IN COVERAGE AND INTENSITY OVER THE PAST SEVERAL HOURS. I CONSIDERED DECREASING THE CURRENT INTENSITY...BUT THE SYSTEM IS PROBABLY UNDERGOING THE USUAL DIURNAL DECREASE THAT WE OBSERVE DURING THE EVENING HOURS. VERTICAL SHEAR IS EXPECTED TO RELAX SOMEWHAT OVER THE NEXT DAY OR SO...HENCE A SLIGHT INCREASE IN STRENGTH IS FORECAST OVER THE 48 HOURS. LATER IN THE PERIOD...ALETTA IS LIKELY TO ENTER A REGION OF STRENGTHENING WEST-SOUTHWESTERLY FLOW AND THE SHEAR COULD INCREASE TO MORE THAN 20 KT IN 2-3 DAYS...WHICH WOULD INHIBIT ANY FURTHER STRENGTHENING. THE OFFICIAL INTENSITY FORECAST FOLLOWS THE SHIPS GUIDANCE RATHER CLOSELY...HOWEVER THERE IS A DISTINCT POSSIBILITY THAT THE INCREASING SHEAR COULD WEAKEN ALETTA MORE THAN EXPECTED IN 3-5 DAYS. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 29/0300Z 16.0N 101.0W 40 KT 12HR VT 29/1200Z 16.2N 101.0W 40 KT 24HR VT 30/0000Z 16.5N 101.2W 45 KT 36HR VT 30/1200Z 16.6N 101.5W 50 KT 48HR VT 31/0000Z 16.6N 102.4W 50 KT 72HR VT 01/0000Z 16.5N 104.0W 50 KT 96HR VT 02/0000Z 16.5N 105.5W 50 KT 120HR VT 03/0000Z 16.5N 107.0W 45 KT $$ NNNN
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Page last modified: Monday, 11-Sep-2006 11:28:39 UTC