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#50106 (Received by flhurricane at: 7:52 AM 05.Oct.2005) TCDAT1 TROPICAL STORM TAMMY SPECIAL DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 730 AM EDT WED OCT 05 2005 RADAR IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT A WELL-DEFINED SURFACE CIRCULATION HAS DEVELOPED DURING THE PAST FEW HOURS WITHIN THE LARGE AREA OF DISTURBED WEATHER NORTH OF THE BAHAMAS AND OVER NORTHERN FLORIDA. THE OVERALL ORGANIZATION OF THE SYSTEM IS SUFFICIENT TO CLASSIFY IT AS A TROPICAL CYCLONE. WSR-88D RADAR IMAGERY BEGAN TO DEPICT A CLOSED CIRCULATION AFTER ABOUT 06Z THIS MORNING... WHICH BECAME WELL-DEFINED BY 08Z ABOUT 40 MILES EAST OF MELBOURNE FLORIDA. SURFACE WIND DIRECTION OBSERVATIONS ALONG THE EAST-CENTRAL FLORIDA COAST ARE CONSISTENT WITH THE LOCATION OF THE CIRCULATION ON RADAR... ALTHOUGH THE WINDS NEAR AND TO THE WEST OF THE CENTER ARE WEAK. ALL OF THE STRONGER WINDS AND CONVECTION OCCUPY THE NORTHEASTERN SEMICIRCLE OF THE SYSTEM... MOST OF IT WELL REMOVED FROM THE CENTER. SHIP AND BUOY OBSERVATIONS OF 30 KT HAVE BEEN COMMON THIS MORNING... BUT MOSTLY OUTSIDE OF THE REGIONS OF STRONGEST RADAR ECHOES... SO IT SEEMS SAFE TO ASSUME THAT TROPICAL STORM FORCE WINDS ARE OCCURRING IN AREAS OF DEEPEST CONVECTION. THE ADVISORY INTENSITY IS SET TO 35 KT. TROPICAL STORM TAMMY IS MOVING FAIRLY RAPIDLY TOWARD THE NORTH-NORTHWEST...WITH ESTIMATED INITIAL MOTION OF 335/14 BASED PRIMARILY ON RADAR FIXES. THE STEERING IS BEING PROVIDED BY THE SOUTHERLY FLOW IN BETWEEN A DEVELOPING MID/UPPER LEVEL LOW IN THE EASTERN GULF OF MEXICO AND A RIDGE OVER THE WESTERN ATLANTIC. THE DYNAMICAL MODELS FORECAST THE LOW OVER THE GULF TO DEEPEN SOMEWHAT WHILE THE RIDGE OVER THE MID-ATLANTIC COAST MOVES OFFSHORE. THEREFORE... ONLY A SUBTLE BEND TO THE WEST IN THE HEADING DURING THE NEXT COUPLE OF DAYS IS FORECAST... WITH A GRADUAL DECREASE IN FORWARD SPEED. DUE TO THE ANGLE OF APPROACH OF THE CENTER OF TAMMY TO THE COASTLINE... IT IS DIFFICULT TO SPECIFY THE LANDFALL TIME OR LOCATION OF THE CENTER. HOWEVER... IT IS MORE IMPORTANT TO FOCUS ON THE LARGE AREA OF WINDS AND CONVECTION TO THE NORTH AND EAST OF THE CENTER... WHICH NECESSITATES A TROPICAL STORM WARNING FOR A LONG STRETCH OF COASTLINE. SINCE TAMMY IS UNDER MODERATE SOUTHERLY SHEAR... ONLY SLIGHT STRENGTHENING APPEARS LIKELY... AND THE ASYMMETRIC CLOUD PATTERN WILL PROBABLY PERSIST. TAMMY HAS THE POTENTIAL TO BE A SIGNIFICANT RAINFALL EVENT FOR PORTIONS OF THE SOUTHEASTERN UNITED STATES. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 05/1130Z 28.4N 80.3W 35 KT 12HR VT 05/1800Z 29.4N 81.1W 40 KT...NEAR COASTLINE 24HR VT 06/0600Z 30.9N 82.4W 30 KT...INLAND 36HR VT 06/1800Z 31.9N 83.5W 25 KT...DISSIPATING 48HR VT 07/0600Z 32.8N 84.4W 20 KT...REMNANT LOW 72HR VT 08/0600Z...DISSIPATED |