ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GUILLERMO DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 PM PDT THU AUG 07 2003 VISIBLE...INFRARED...AND MICROWAVE SATELLITE IMAGERY INDICATE THAT TROPICAL DEPRESSION SEVEN-E HAS BECOME MUCH BETTER ORGANIZED OVER THE PAST 6 HOURS. OUTFLOW CONTINUES TO IMPROVE AND A SMALL CENTRAL DENSE OVERCAST...OR CDO...FEATURE HAS DEVELOPED OVER THE LOW-LEVEL CENTER. SATELLITE INTENSITY ESTIMATES FROM BOTH TAFB AND SAB ARE T2.5 PLUS...OR 40 KT...SO THE INITIAL INTENSITY IS SET AT 40 KT AND THE DEPRESSION IS UPGRADED TO TROPICAL STORM GUILLERMO. THE INITIAL MOTION ESTIMATE IS 280/06. THE MORE SOUTHERLY POSITION AND SLOWER FORWARD SPEED IS LIKELY A TEMPORARY CONDITION...AND IS PROBABLY DUE TO THE LOW-LEVEL CENTER RE-ORGANIZING WITHIN THE CENTRAL DEEP CONVECTION. A GRADUAL INCREASE IN FORWARD SPEED IS EXPECTED TO RESUME SHORTLY. THE GLOBAL MODELS ARE OF LITTLE USE AS FAR AS SPECIFIC TRACK FORECAST POSITIONS ARE CONCERNED SINCE THE MODELS WERE POORLY INITIALIZED AT 07/18Z...AND THEY KILL THE CYCLONE WITHIN THE NEXT 12 HOURS OR SO AT THE EXPENSE OF SPINNING UP A SYSTEM TO THE EAST. HOWEVER...THE BASIC SYNOPTIC PATTERN OF HAVING A STRONG SUBTROPICAL RIDGE TO THE NORTH INDICATES THAT GUILLERMO SHOULD MOVE IN A GENERAL WEST TO PERHAPS SLIGHTLY WEST-NORTHWESTWARD DIRECTION THROUGHOUT THE PERIOD. THE OFFICIAL TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS FORECAST TRACK AND IS SIMILAR TO THE MEDIUM AND DEEP BAM MODELS THROUGH 36 HOURS...BUT SLOWER AND WELL SOUTH OF BOTH OF THOSE MODEL TRACKS AFTER THAT. THE INTENSITY FORECAST WAS INCREASED SIGNIFICANTLY BASED ON THE STRONGER INITIAL INTENSITY...BUT IT IS STILL SLIGHTLY BELOW THE SHIPS MODEL WHICH BRINGS THE CYCLONE UP TO 58 KT IN ABOUT 48-60 HOURS...AFTER WHICH IT REMAINS STEADY THROUGH 120 HOURS. IT IS POSSIBLE THAT GUILLERMO COULD BECOME STRONGER THAN FORECAST AND EVEN REACH MINIMAL HURRICANE STRENGTH BY 36-48 HOURS GIVEN THAT THE SHEAR IS EXPECTED TO BE AROUND 10 KT OR LESS AND THE CENTER IS FORECAST BE VERY CLOSE TO THE 27C SST ISOTHERM. THE 34-KT WIND RADII WERE ALSO DECREASED SLIGHTLY BASED ON A SLOWER FORWARD SPEED. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 08/0300Z 16.7N 117.5W 40 KT 12HR VT 08/1200Z 16.9N 118.7W 45 KT 24HR VT 09/0000Z 17.2N 120.3W 50 KT 36HR VT 09/1200Z 17.4N 122.1W 55 KT 48HR VT 10/0000Z 17.5N 124.0W 55 KT 72HR VT 11/0000Z 17.5N 127.5W 55 KT 96HR VT 12/0000Z 17.5N 131.0W 50 KT 120HR VT 13/0000Z 17.5N 135.0W 45 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:56 UTC