ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM DEAN DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 1100 PM EDT WED AUG 15 2007 DEAN HAS CONTINUED TO GRADUALLY BECOME BETTER ORGANIZED THIS EVENING...WITH A 2311 UTC TRMM PASS SUGGESTING THAT A SMALL BANDING EYE FEATURE MAY BE FORMING. THE 00Z DVORAK SATELLITE INTENSITY ESTIMATES WERE 55 KT...HOWEVER...THE SATELLITE APPEARANCE HAS IMPROVED SINCE THEN AND THE ADVISORY INTENSITY HAS BEEN INCREASED TO 60 KT. THE INITIAL MOTION ESTIMATE IS 280/20. DEAN IS FORECAST TO CONTINUE MOVING WEST TO WEST-NORTHWESTWARD SOUTH OF A DEEP-LAYER RIDGE LOCATED OVER THE CENTRAL ATLANTIC. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED ON THIS MOTION DURING THE NEXT 72 HOURS. AT DAYS 4 AND 5...THE TRACK GUIDANCE HAS A BIT MORE SPREAD...BUT STILL IS IN GOOD AGREEMENT ON A CONTINUED WEST-NORTHWEST MOTION INTO THE NORTHWESTERN CARIBBEAN SEA. THE GLOBAL MODELS SHOW VERY LITTLE INTERACTION BETWEEN DEAN AND A MIDDLE-LEVEL TROUGH CURRENTLY OVER THE BAHAMAS...AS THEY CONTINUE TO MOVE THE TROUGH WESTWARD AHEAD OF DEAN. THE NOGAPS IS A LITTLE SLOWER TO MOVE THE TROUGH WEST AND ITS TRACK IS THEREFORE A LITTLE FARTHER NORTH THAN THE REST OF THE GUIDANCE. THE NEW OFFICIAL TRACK FORECAST IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE AND CLOSE TO THE GUNA MODEL CONSENSUS. THERE ARE SEEMINGLY FEW FACTORS THAT WOULD INHIBIT STRENGTHENING DURING THE FORECAST PERIOD. AS MENTIONED IN THE PREVIOUS DISCUSSION...THE MODELS UNANIMOUSLY DEVELOP A LARGE UPPER-LEVEL ANTICYCLONE OVER DEAN AS IT MOVES INTO THE CARIBBEAN SEA. MYSTERIOUSLY...THE GFDL AND HWRF MODELS HAVE BACKED OFF ON THEIR RESPECTIVE INTENSITY FORECASTS. HOWEVER...THE SHIPS AND LGEM MODELS CONTINUE TO INDICATE STEADY STRENGTHENING AND THE OFFICIAL INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS ADVISORY. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT WILL BE INVESTIGATING DEAN TOMORROW AFTERNOON...AND THE NOAA GULFSTREAM-IV WILL CONDUCT A SYNOPTIC SURVEILLANCE MISSION FOR THE 17/00Z ANALYSIS CYCLE. FORECAST POSITIONS AND MAX WINDS INITIAL 16/0300Z 13.1N 50.2W 60 KT 12HR VT 16/1200Z 13.6N 53.2W 65 KT 24HR VT 17/0000Z 14.2N 57.2W 70 KT 36HR VT 17/1200Z 14.8N 61.1W 75 KT 48HR VT 18/0000Z 15.3N 64.7W 85 KT 72HR VT 19/0000Z 16.3N 71.5W 95 KT 96HR VT 20/0000Z 17.8N 78.5W 105 KT 120HR VT 21/0000Z 19.5N 85.5W 115 KT $$ FORECASTER BROWN NNNN
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Page last modified: Friday, 02-Nov-2007 21:20:43 UTC