000 WTNT34 KNHC 280254 TCPAT4 BULLETIN TROPICAL STORM ISAAC ADVISORY NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 1000 PM CDT MON AUG 27 2012 ...ISAAC TAKING AIM ON THE NORTHERN GULF COAST...SIGNIFICANT STORM SURGE AND FRESHWATER FLOOD THREAT EXPECTED... SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...27.1N 87.0W ABOUT 190 MI...305 KM SE OF THE MOUTH OF THE MISSISSIPPI RIVER ABOUT 255 MI...410 KM SSE OF BILOXI MISSISSIPPI MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...979 MB...28.91 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 ALABAMA-FLORIDA 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... * FROM THE ALABAMA-FLORIDA BORDER TO THE AUCILLA RIVER * INTRACOASTAL CITY TO MORGAN CITY LOUISIANA A TROPICAL STORM WATCH IS IN EFFECT FOR... * EAST OF SABINE PASS TO WEST OF INTRACOASTAL CITY 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...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 1000 PM CDT...0300 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE 27.1 NORTH...LONGITUDE 87.0 WEST. ISAAC IS MOVING TOWARD THE NORTHWEST NEAR 10 MPH...17 KM/H. THIS GENERAL MOTION WITH SOME DECREASE IN FORWARD SPEED IS EXPECTED DURING THE NEXT DAY OR TWO. ON THE FORECAST TRACK...THE CENTER OF ISAAC WILL MOVE OVER THE CENTRAL GULF OF MEXICO TONIGHT AND APPROACH THE COAST OF SOUTHEASTERN LOUISIANA AND MISSISSIPPI TUESDAY AFTERNOON OR TUESDAY NIGHT. MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER GUSTS. STRENGTHENING IS FORECAST...AND ISAAC IS EXPECTED TO BECOME A HURRICANE TONIGHT OR EARLY TUESDAY...AND CONTINUE TO STRENGTHEN UNTIL LANDFALL OCCURS ALONG THE NORTHERN GULF COAST. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205 MILES...335 KM FROM THE CENTER. THE LATEST MINIMUM CENTRAL PRESSURE JUST REPORTED BY AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WAS 979 MB...28.91 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... * SOUTHEAST LOUISIANA AND MISSISSIPPI...6 TO 12 FT * ALABAMA...6 TO 9 FT * SOUTH-CENTRAL LOUISIANA...3 TO 6 FT * FLORIDA PANHANDLE...3 TO 6 FT * FLORIDA WEST COAST INCLUDING APALACHEE BAY...1 TO 3 FT THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF ONSHORE FLOW. 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 ARE EXPECTED TO SPREAD NORTHWARD INTO THE FLORIDA BIG BEND AREA AND THE FLORIDA PANHANDLE IN THE TROPICAL STORM WARNING AREA OVERNIGHT AND TUESDAY. TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE NORTHERN GULF COAST IN THE HURRICANE WARNING AREA OVERNIGHT...WITH HURRICANE CONDITIONS EXPECTED BY TUESDAY AFTERNOON. RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 6 TO 12 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 18 INCHES...IN SOUTHEASTERN LOUISIANA...SOUTHERN MISSISSIPPI... SOUTHERN ALABAMA AND THE EXTREME WESTERN FLORIDA PANHANDLE. TORNADOES...ISOLATED TORNADOES ARE POSSIBLE ACROSS WEST-CENTRAL AND NORTHWESTERN FLORIDA THROUGH TONIGHT...AND ALONG THE NORTHERN GULF COAST LATE TONIGHT AND TUESDAY. SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO AFFECT THE FLORIDA COASTLINE AND THE FLORIDA KEYS DURING THE NEXT DAY OR SO...AND BEGIN TO AFFECT PORTIONS OF THE NORTHERN GULF COAST EARLY TUESDAY. NEXT ADVISORY ------------- NEXT INTERMEDIATE ADVISORY...100 AM CDT. NEXT COMPLETE ADVISORY...400 AM CDT. $$ FORECASTER BROWN/BLAKE