000 WTNT34 KNHC 291054 TCPAT4 BULLETIN HURRICANE ISAAC INTERMEDIATE ADVISORY NUMBER 33A NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 600 AM CDT WED AUG 29 2012 ...ISAAC CONTINUES TO LASH NEW ORLEANS...DANGEROUS STORM SURGE AND FLOOD THREAT FROM HEAVY RAINS LIKELY TO CONTINUE THROUGH TODAY AND TONIGHT... SUMMARY OF 600 AM CDT...1100 UTC...INFORMATION ---------------------------------------------- LOCATION...29.4N 90.5W ABOUT 20 MI...30 KM SE OF HOUMA LOUISIANA ABOUT 50 MI...75 KM SSW OF NEW ORLEANS LOUISIANA MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...970 MB...28.64 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 SABINE PASS TEXAS A TROPICAL STORM WATCH IS IN EFFECT FOR... * EAST OF HIGH ISLAND TEXAS TO JUST WEST OF SABINE PASS 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 600 AM CDT...1100 UTC...THE CENTER OF HURRICANE ISAAC WAS LOCATED NEAR LATITUDE 29.4 NORTH...LONGITUDE 90.5 WEST. ISAAC HAS BEEN WOBBLING OVER THE PAST COUPLE OF HOURS...BUT A GENERAL NORTHWESTWARD MOTION NEAR 6 MPH...9 KM/H...IS EXPECTED THIS MORNING. A NORTHWESTWARD MOTION IS EXPECTED TO CONTINUE THROUGH TONIGHT...FOLLOWED BY A TURN TOWARD THE NORTH-NORTHWEST BY THURSDAY NIGHT OR EARLY FRIDAY. ON THE FORECAST TRACK...THE CENTER OF ISAAC WILL MOVE OVER LOUISIANA TODAY AND TOMORROW...AND OVER SOUTHERN ARKANSAS EARLY FRIDAY. MAXIMUM SUSTAINED WINDS ARE NEAR 80 MPH...130 KM/H...WITH HIGHER GUSTS. ISAAC IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON HURRICANE WIND SCALE. WEAKENING IS FORECAST AS ISAAC MOVES OVER LAND DURING THE NEXT 48 HOURS. HURRICANE-FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM THE CENTER...AND TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM. DURING THE PAST HOUR...A SUSTAINED WIND OF 54 MPH WITH A GUST TO 70 MPH WAS REPORTED AT LAKEFRONT AIRPORT IN NEW ORLEANS...A SUSTAINED WIND OF 46 MPH WITH A GUST TO 69 MPH WAS REPORTED AT NEW CANAL STATION IN NEW ORLEANS...AND A SUSTAINED WIND OF 58 MPH WITH A GUST TO 73 MPH WAS REPORTED AT SHELL BEACH LOUISIANA. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB...28.64 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...3 TO 6 FT * SOUTH-CENTRAL LOUISIANA...3 TO 6 FT * FLORIDA PANHANDLE AND APALACHEE BAY...2 TO 4 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 ACROSS THE WARNING AREA THIS MORNING...AND HURRICANE CONDITIONS WILL CONTINUE TO AFFECT PORTIONS OF SOUTHEASTERN LOUISIANA IN THE HURRICANE WARNING AREA. 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...AND SOUTHWEST ALABAMA THROUGH FRIDAY MORNING. THESE RAINS COULD RESULT IN SIGNIFICANT LOWLAND FLOODING. RAINS ARE EXPECTED TO INCREASE NORTHWARD INTO ARKANSAS ON THURSDAY WITH AMOUNTS OF 3 TO 6 INCHES EXPECTED OVER SOUTHERN ARKANSAS BY FRIDAY MORNING. TORNADOES...ISOLATED TORNADOES ARE POSSIBLE ALONG THE CENTRAL GULF COAST REGION AND PARTS OF THE LOWER MISSISSIPPI RIVER VALLEY THROUGH WEDNESDAY. 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...800 AM CDT. NEXT COMPLETE ADVISORY...1000 AM CDT. $$ FORECASTER PASCH/ROBERTS/STEWART