000 WTNT34 KNHC 301438 TCPAT4 BULLETIN TROPICAL STORM ISAAC ADVISORY NUMBER 38 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 1000 AM CDT THU AUG 30 2012 ...ISAAC SLOWLY WEAKENING OVER CENTRAL LOUISIANA BUT STILL PRODUCING HEAVY RAINS...SEVERE WEATHER...AND HIGH WATER LEVELS ALONG THE NORTHERN GULF COAST... SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...31.7N 92.1W ABOUT 50 MI...80 KM S OF MONROE LOUISIANA ABOUT 165 MI...270 KM NW OF NEW ORLEANS LOUISIANA MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...NNW OR 330 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...987 MB...29.15 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY... THE TROPICAL STORM WARNING HAS BEEN DISCONTINUED WEST OF MORGAN CITY LOUISIANA. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A TROPICAL STORM WARNING IS IN EFFECT FOR... * MORGAN CITY LOUISIANA TO THE MISSISSIPPI-ALABAMA BORDER... INCLUDING LAKE PONTCHARTRAIN AND LAKE MAUREPAS FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 1000 AM CDT...1500 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE 31.7 NORTH...LONGITUDE 92.1 WEST. ISAAC IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 9 MPH...15 KM/H. A TURN TOWARD THE NORTH IS EXPECTED BY FRIDAY. ON THE FORECAST TRACK...THE CENTER OF ISAAC WILL CONTINUE TO MOVE OVER LOUISIANA TODAY...OVER ARKANSAS ON FRIDAY...AND OVER SOUTHERN MISSOURI FRIDAY NIGHT. MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 40 MPH...65 KM/H...WITH HIGHER GUSTS. FURTHER WEAKENING IS FORECAST DURING THE NEXT 48 HOURS AS THE STORM CONTINUES TO MOVE OVER LAND...AND ISAAC IS EXPECTED TO BECOME A TROPICAL DEPRESSION BY TONIGHT. TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 195 MILES...315 KM...MAINLY TO THE SOUTHEAST OF THE CENTER OVER WATER AND ALONG THE COASTS OF MISSISSIPPI AND SOUTHEASTERN LOUISIANA. THE ESTIMATED MINIMUM CENTRAL PRESSURE BASED ON NEARBY SURFACE OBSERVATIONS 987 MB...29.15 INCHES. HAZARDS AFFECTING LAND ---------------------- EVEN THOUGH ISAAC IS NO LONGER A HURRICANE...LIFE-THREATENING HAZARDS FROM STORM SURGE...INLAND FLOODING...AND TORNADOES ARE STILL OCCURRING. STORM SURGE...THE COMBINATION OF A STORM SURGE AND THE TIDE WILL CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY RISING WATERS. THE WATER COULD REACH THE FOLLOWING DEPTHS ABOVE GROUND IF THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE... * MISSISSIPPI AND SOUTHEASTERN LOUISIANA...4 TO 8 FT * ALABAMA...2 TO 4 FT * SOUTH-CENTRAL LOUISIANA...1 TO 3 FT * FLORIDA PANHANDLE...1 TO 2 FT THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF ONSHORE WINDS. SURGE-RELATED FLOODING DEPENDS ON THE RELATIVE TIMING OF THE SURGE AND THE TIDAL CYCLE...AND CAN VARY GREATLY OVER SHORT DISTANCES. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE SEE PRODUCTS ISSUED BY YOUR LOCAL WEATHER SERVICE OFFICE. NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DANGEROUS WAVES. BASED ON OBSERVATIONS FROM NATIONAL OCEAN SERVICE TIDE GAUGES...AT NEW CANAL STATION LOUISIANA...A STORM SURGE OF NEAR 6 FEET IS STILL OCCURRING ON THE SOUTHERN SHORE OF LAKE PONTCHARTRAIN...AND A STORM SURGE VALUE OF NEAR 5 FEET IS OCCURRING AT WAVELAND MISSISSIPPI. WIND...TROPICAL STORM CONDITIONS WILL CONTINUE ACROSS THE WARNING AREA THROUGH THIS MORNING. RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 7 TO 14 INCHES...WITH ISOLATED MAXIMUM AMOUNTS OF 25 INCHES POSSIBLE...OVER NORTHERN AND EASTERN LOUISIANA....MUCH OF MISSISSIPPI...SOUTHWESTERN ALABAMA...ARKANSAS AND INTO SOUTHERN MISSOURI THROUGH FRIDAY. THESE RAINS COULD RESULT IN SIGNIFICANT LOWLAND FLOODING. THE HEAVY RAIN POTENTIAL WILL BE SPREADING EASTWARD THIS WEEKEND INTO PORTIONS OF THE MID-WEST AND OHIO VALLEY REGIONS. TORNADOES...TORNADOES ARE POSSIBLE ALONG THE CENTRAL GULF COAST REGION AND PARTS OF THE LOWER MISSISSIPPI RIVER VALLEY THROUGH TODAY. SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO AFFECT THE WEST COAST OF FLORIDA AND THE NORTHERN GULF COAST FOR THE NEXT DAY OR SO. NEXT ADVISORY ------------- NEXT INTERMEDIATE ADVISORY...100 PM CDT. NEXT COMPLETE ADVISORY...400 PM CDT. $$ FORECASTER STEWART