ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ISAAC DISCUSSION NUMBER 38 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 1000 AM CDT THU AUG 30 2012 CENTER FIXES USING SURFACE OBSERVATIONS AND NOAA DOPPLER WEATHER RADARS INDICATE THAT ISAAC IS MOVING NORTHWESTWARD AT 330/08 KT. THE FORECAST TACK AND REASONING REMAIN BASICALLY UNCHANGED FROM THE PREVIOUS ADVISORY. ISAAC AND ITS REMNANTS ARE EXPECTED TO BE STEERED NORTHWARD AROUND THE WESTERN PORTION OF A SUBTROPICAL RIDGE THAT IS LOCATED OVER THE SOUTHEASTERN U.S. THROUGH DAY 2...AND THEN TURN NORTHEASTWARD AND EASTWARD ON DAY 3-5 AS THE SYSTEM MOVES INTO WEAK MID-LATITUDE WESTERLY FLOW. THE OFFICIAL TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS ONE...AND LIES CLOSE TO THE LATEST DYNAMICAL MODEL CONSENSUS. THE INITIAL INTENSITY HAS BEEN DECREASED TO 35 KT...AND THAT IS IN SMALL AREA OVER WATER BETWEEN SOUTHEASTERN LOUISIANA AND THE MISSISSIPPI COAST...AND PERHAPS EXTENDING A FEW MILES INLAND. ISAAC WILL CONTINUE TO WEAKEN OVER LAND AND IT IS LIKELY TO BECOME A TROPICAL DEPRESSION BY THIS EVENING...AND BECOME A POST-TROPICAL REMNANT LOW BY SATURDAY...IF NOT SOONER. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND CLOSELY FOLLOWS THE DECAY-SHIPS STATISTICAL-DYNAMICAL INTENSITY MODEL. HEAVY RAINFALL AND A SIGNIFICANT FLOOD THREAT WILL CONTINUE 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. THE THREAT FOR TORNADOES WITH THIS SYSTEM ALSO APPEARS TO BE INCREASING TODAY. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 31.7N 92.1W 35 KT 40 MPH...INLAND 12H 31/0000Z 33.0N 92.8W 30 KT 35 MPH...INLAND 24H 31/1200Z 35.0N 93.3W 25 KT 30 MPH...INLAND 36H 01/0000Z 37.0N 93.3W 20 KT 25 MPH...INLAND 48H 01/1200Z 38.4N 92.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 02/1200Z 39.4N 89.2W 15 KT 15 MPH...POST-TROP/REMNT LOW 96H 03/1200Z 39.5N 86.0W 15 KT 15 MPH...POST-TROP/REMNT LOW 120H 04/1200Z 39.5N 83.0W 15 KT 15 MPH...POST-TROP/REMNT LOW $$ FORECASTER STEWART NNNN
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Page last modified: Monday, 31-Dec-2012 12:09:27 UTC