000 WTNT34 KNHC 301142 TCPAT4 BULLETIN TROPICAL STORM ISAAC INTERMEDIATE ADVISORY NUMBER 37A NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 700 AM CDT THU AUG 30 2012 ...ISAAC CONTINUES TO MOVE SLOWLY NORTHWESTWARD OVER CENTRAL LOUISIANA...STILL PRODUCING HEAVY RAINS...SEVERE WEATHER...AND HIGH WATER LEVELS ALONG THE NORTHERN GULF COAST... SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...31.1N 91.8W ABOUT 35 MI...60 KM SE OF ALEXANDRIA LOUISIANA ABOUT 125 MI...205 KM NW OF NEW ORLEANS LOUISIANA MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...NW OR 325 DEGREES AT 8 MPH...13 KM/H MINIMUM CENTRAL PRESSURE...985 MB...29.09 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY... NONE. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A TROPICAL STORM WARNING IS IN EFFECT FOR... * INTRACOASTAL 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 700 AM CDT...1200 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE 31.1 NORTH...LONGITUDE 91.8 WEST. ISAAC IS MOVING TOWARD THE NORTHWEST NEAR 8 MPH...13 KM/H. A TURN TOWARD THE NORTH-NORTHWEST IS EXPECTED LATER TODAY...FOLLOWED BY A TURN TOWARD THE NORTH ON 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 ARE NEAR 45 MPH...75 KM/H... WITH HIGHER GUSTS. THE STRONGEST WINDS ARE PRIMARILY OCCURRING OVER WATER OR NEAR THE COAST. STEADY WEAKENING IS EXPECTED DURING THE NEXT 48 HOURS AS ISAAC CONTINUES TO MOVE OVER LAND. ISAAC IS FORECAST TO BECOME A TROPICAL DEPRESSION BY TONIGHT. TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM...MAINLY EAST THROUGH SOUTH OF THE CENTER. THE ESTIMATED MINIMUM CENTRAL PRESSURE BASED ON NEARBY SURFACE OBSERVATIONS IS 985 MB...29.09 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...5 TO 10 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 AMOUNTS OF 7 TO 14 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 25 INCHES...OVER MUCH OF LOUISIANA...MISSISSIPPI...SOUTHWEST ALABAMA AND ARKANSAS THROUGH FRIDAY. THESE RAINS COULD RESULT IN SIGNIFICANT LOWLAND FLOODING. AN UNOFFICIAL REPORT OF A RAINFALL TOTAL OF 23.31 INCHES HAS BEEN RECEIVED FROM GRETNA LOUISIANA. TORNADOES...ISOLATED 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 COMPLETE ADVISORY...1000 AM CDT. $$ FORECASTER STEWART/BLAKE