000 WTNT34 KNHC 282045 TCPAT4 BULLETIN HURRICANE ISAAC ADVISORY NUMBER 31 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 400 PM CDT TUE AUG 28 2012 ...ISAAC GETTING BETTER ORGANIZED AS IT NEARS SOUTHEASTERN LOUISIANA...FLOODING FROM STORM SURGE AND RAINFALL EXPECTED... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...28.7N 89.2W ABOUT 30 MI...45 KM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER ABOUT 105 MI...170 KM SSE OF NEW ORLEANS LOUISIANA MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 8 MPH...13 KM/H MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY... NONE. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A HURRICANE WARNING IS IN EFFECT FOR... * EAST OF MORGAN CITY LOUISIANA TO THE MISSISSIPPI-ALABAMA BORDER... INCLUDING METROPOLITAN NEW ORLEANS...LAKE PONTCHARTRAIN...AND LAKE MAUREPAS A HURRICANE WATCH IS IN EFFECT FOR... * INTRACOASTAL CITY TO MORGAN CITY LOUISIANA A TROPICAL STORM WARNING IS IN EFFECT FOR... * THE MISSISSIPPI-ALABAMA BORDER TO DESTIN FLORIDA * MORGAN CITY TO CAMERON LOUISIANA A TROPICAL STORM WATCH IS IN EFFECT FOR... * EAST OF HIGH ISLAND TEXAS TO JUST WEST OF CAMERON LOUISIANA A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION. A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA. A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA. 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 400 PM CDT...2100 UTC...THE CENTER OF HURRICANE ISAAC WAS LOCATED BY NOAA DOPPLER RADARS NEAR LATITUDE 28.7 NORTH...LONGITUDE 89.2 WEST. ISAAC IS MOVING TOWARD THE NORTHWEST NEAR 8 MPH...13 KM/H. A NORTHWESTWARD MOTION AT A SLIGHTLY SLOWER SPEED IS EXPECTED OVER THE NEXT DAY OR TWO. ON THE FORECAST TRACK...THE CENTER OF HURRICANE ISAAC SHOULD REACH THE COASTLINE OF SOUTHEASTERN LOUISIANA THIS EVENING. MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 80 MPH...130 KM/H... WITH HIGHER GUSTS. ISAAC IS A CATEGORY ONE HURRICANE ON THE SAFFIR- SIMPSON HURRICANE WIND SCALE. SOME SLIGHT STRENGTHENING IS POSSIBLE BEFORE ISAAC MAKES LANDFALL. GRADUAL WEAKENING IS EXPECTED AFTER LANDFALL OCCURS. HURRICANE-FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...MAINLY TO THE NORTHEAST AND EAST OF THE CENTER. TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 185 MILES...295 KM. TROPICAL STORM CONDITIONS ARE OCCURRING ALONG THE COASTAL AREAS OF SOUTHEASTERN LOUISIANA...MISSISSIPPI...AND ALABAMA. NOAA BUOY 42040...LOCATED EAST OF THE MOUTH OF THE MISSISSIPPI RIVER...RECENTLY MEASURED SUSTAINED WINDS OF 63 MPH...100 KM/H...AND A GUST TO 83 MPH... 135 KM/H. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB...28.79 INCHES. HAZARDS AFFECTING LAND ---------------------- 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...6 TO 12 FT * ALABAMA...4 TO 8 FT * SOUTH-CENTRAL LOUISIANA...3 TO 6 FT * FLORIDA PANHANDLE...3 TO 6 FT * APALACHEE BAY...2 TO 4 FT * REMAINDER OF FLORIDA WEST COAST...1 TO 3 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. WIND...TROPICAL STORM CONDITIONS WILL CONTINUE TO SPREAD ACROSS THE WARNING AREA THIS EVENING...AND HURRICANE CONDITIONS SHOULD SPREAD ONSHORE ACROSS SOUTHEASTERN LOUISIANA DURING THE NEXT FEW HOURS. WINDS AFFECTING THE UPPER FLOORS OF HIGH-RISE BUILDINGS WILL BE SIGNIFICANTLY STRONGER THAN THOSE NEAR GROUND LEVEL. AT ABOUT THE 30TH STORY...WINDS WOULD LIKELY BE ONE SAFFIR-SIMPSON CATEGORY STRONGER THAN AT THE SURFACE. RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 7 TO 14 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 20 INCHES...OVER MUCH OF LOUISIANA...SOUTHERN MISSISSIPPI...SOUTHERN ALABAMA...AND THE EXTREME WESTERN FLORIDA PANHANDLE. THESE RAINS COULD RESULT IN SIGNIFICANT LOWLAND FLOODING. TORNADOES...TORNADOES ARE POSSIBLE ALONG THE NORTHERN GULF COAST THROUGH TONIGHT. SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO AFFECT THE WEST COAST OF FLORIDA AND PORTIONS OF THE NORTHERN GULF COAST FOR THE NEXT DAY OR SO. NEXT ADVISORY ------------- NEXT INTERMEDIATE ADVISORIES...600 PM CDT AND 800 PM CDT. NEXT COMPLETE ADVISORY...1000 PM CDT. $$ FORECASTER STEWART