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#3239 (Received by flhurricane at: 5:35 PM 31.Jul.2004) TCDAT1 TROPICAL DEPRESSION ONE DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT SAT JUL 31 2004 THE LOW PRESSURE AREA OFF THE NORTHEAST FLORIDA COAST HAS SHOWN INCREASING CONVECTIVE ORGANIZATION THIS AFTERNOON...WITH SATELLITE INTENSITY ESTIMATES OF 30 KT FROM TAFB AND 25 KT FROM SAB. THUS... ADVISORIES ARE BEING INITIATED ON THE SYSTEM AS TROPICAL DEPRESSION ONE WITH 25 KT WINDS. WHILE THE DEPRESSION HAS A LARGE CYCLONIC ENVELOPE...THE CENTER WAS VERY POORLY DEFINED ON THE RECONNAISSANCE FLIGHT THIS MORNING...AND IT WOULD NOT BE A SURPRISE IF THE FLIGHT SCHEDULED FOR 0000Z FINDS THE SAME. THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 315/8. THE DEPRESSION IS CURRENTLY BEING STEERED BY THE WESTERN END OF THE SUBTROPICAL RIDGE...WHILE WATER VAPOR IMAGERY AND LARGE-SCALE MODELS SHOW DEEP-LAYER TROUGHING OVER THE CENTRAL UNITED STATES MOVING EASTWARD. ALL GUIDANCE SHOWS THE CYCLONE RECURVING NORTHEASTWARD AHEAD OF THE TROUGH...WITH THE BIGGEST DIFFERENCES IN THE GUIDANCE BEING HOW FAST IT MOVES AFTER RECURVATURE. THE OFFICIAL FORECAST TRACK WILL CALL FOR THE SYSTEM TO TURN NORTHWARD AT ABOUT 24 HR AND NORTHEASTWARD AFTER 36 HR...BRUSHING THE SOUTHEASTERN U.S. COAST. WHILE THE OFFICIAL TRACK CALLS FOR LANDFALL IN NORTH CAROLINA... SEVERAL MODELS RECURVE THE CYCLONE SHARPLY ENOUGH TO KEEP THE CENTER OFFSHORE. THIS LARGE AND POORLY DEFINED SYSTEM WILL LIKELY TAKE TIME TO CONSOLIDATE EVEN THOUGH CONDITIONS GENERALLY APPEAR FAVORABLE FOR INTENSIFICATION. THE INTENSITY FORECAST THUS CALLS FOR SLOW STRENGTHENING UNTIL THE SYSTEM REACHES THE COAST. WHAT INTENSIFICATION MAY OCCUR AFTER THE CYCLONE CLEARS THE U.S. EAST COAST IS QUESTIONABLE...AS THE LARGE SCALE MODELS DISAGREE ON WHETHER IT WILL DISSIPATE OR STRENGTHEN DURING INTERACTION WITH THE WESTERLIES. FOR NOW...THE INTENSITY FORECAST WILL COMPROMISE BETWEEN THE TWO EXTREMES AND KEEP A STEADY 40 KT UNTIL EXTRATROPICAL TRANSITION. THE PROXIMITY TO THE COAST REQUIRES A TROPICAL STORM WATCH TO BE ISSUED FOR PORTIONS OF THE COASTS OF NORTH AND SOUTH CAROLINA AT THIS TIME. A TROPICAL STORM WARNING MAY BE REQUIRED IN A LATER ADVISORY. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 31/2100Z 30.6N 78.6W 25 KT 12HR VT 01/0600Z 31.5N 79.3W 30 KT 24HR VT 01/1800Z 32.9N 79.2W 35 KT 36HR VT 02/0600Z 34.0N 78.0W 40 KT...INLAND 48HR VT 02/1800Z 35.2N 76.6W 40 KT...INLAND 72HR VT 03/1800Z 37.5N 73.5W 40 KT...OVER WATER 96HR VT 04/1800Z 40.0N 69.0W 40 KT 120HR VT 05/1800Z 46.0N 57.5W 40 KT...EXTRATROPICAL |