ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ISAAC DISCUSSION NUMBER 37 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 400 AM CDT THU AUG 30 2012 ISAAC IS SLOWLY WEAKENING AS MORE OF ITS LARGE CIRCULATION MOVES OVER LAND. BASED ON THE LATEST SURFACE WIND OBSERVATIONS NEAR THE NORTHERN GULF COAST...THE MAXIMUM WINDS HAVE DIMINISHED TO NEAR 40 KT. THESE WINDS ARE OCCURRING PRIMARILY OVER WATER OR ALONG THE COASTLINE. CONTINUED GRADUAL WEAKENING IS EXPECTED...AND ISAAC IS LIKELY TO BECOME A TROPICAL DEPRESSION BY THIS EVENING. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND IS MORE OR LESS IN AGREEMENT WITH THE STATISTICAL-DYNAMICAL GUIDANCE. CENTER FIXES USING SURFACE SYNOPTIC DATA AND NATIONAL WEATHER SERVICE DOPPLER RADAR IMAGERY INDICATE THAT ISAAC IS MOVING NORTHWESTWARD AT A SLIGHTLY FASTER PACE...325/7. THE TRACK FORECAST AND PROGNOSTIC REASONING REMAIN ESSENTIALLY UNCHANGED. OVER THE NEXT SEVERAL DAYS...THE PRIMARY STEERING MECHANISM SHOULD BE THE FLOW BETWEEN THE MID-LATITUDE WESTERLIES AND A RIDGE OVER THE SOUTHEASTERN UNITED STATES. AS A RESULT THE CYCLONE IS EXPECTED TO TURN NORTHWARD...NORTHEASTWARD...AND EASTWARD DURING THE FORECAST PERIOD. THE OFFICIAL TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS ONE...AND ALSO CLOSE TO THE LATEST DYNAMICAL MODEL CONSENSUS. HEAVY RAINFALL AND A SIGNIFICANT FLOOD THREAT ARE EXPECTED TO SPREAD INLAND ACROSS PORTIONS OF THE CENTRAL UNITED STATES DURING THE NEXT SEVERAL DAYS. WATER LEVELS ALONG THE NORTHERN GULF COAST WILL REMAIN ELEVATED THROUGH AT LEAST THIS MORNING. TORNADOES REMAIN A THREAT AS WELL FROM THIS SYSTEM TODAY. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 30.9N 91.6W 40 KT 45 MPH 12H 30/1800Z 31.9N 92.3W 35 KT 40 MPH...INLAND 24H 31/0600Z 33.8N 93.2W 30 KT 35 MPH...INLAND 36H 31/1800Z 36.0N 93.5W 25 KT 30 MPH...INLAND 48H 01/0600Z 38.0N 93.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 02/0600Z 39.5N 90.0W 15 KT 15 MPH...POST-TROP/REMNT LOW 96H 03/0600Z 40.0N 86.5W 15 KT 15 MPH...POST-TROP/REMNT LOW 120H 04/0600Z 40.5N 82.0W 15 KT 15 MPH...POST-TROP/REMNT LOW $$ FORECASTER PASCH NNNN
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Page last modified: Monday, 31-Dec-2012 12:09:27 UTC