000 WTNT34 KNHC 271139 TCPAT4 BULLETIN TROPICAL STORM ISAAC INTERMEDIATE ADVISORY NUMBER 25A NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 800 AM EDT MON AUG 27 2012 ...ISAAC GETTING A LITTLE BETTER ORGANIZED AS IT MOVES WEST-NORTHWESTWARD OVER THE EASTERN GULF OF MEXICO... SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...25.7N 84.7W ABOUT 185 MI...295 KM WSW OF FT. MYERS FLORIDA ABOUT 360 MI...575 KM SE OF THE MOUTH OF THE MISSISSIPPI RIVER MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...988 MB...29.18 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 DESTIN FLORIDA...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 FLORIDA PENINSULA FROM OCEAN REEF SOUTHWARD ON THE EAST COAST AND FROM TARPON SPRINGS SOUTHWARD ON THE WEST COAST * FLORIDA KEYS...INCLUDING THE DRY TORTUGAS AND FLORIDA BAY * EAST OF DESTIN FLORIDA TO THE SUWANNEE 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. A WARNING IS TYPICALLY ISSUED 36 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL STORM FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR DANGEROUS. 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 WATCH IS TYPICALLY ISSUED 48 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL STORM FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR DANGEROUS. A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS. FOR STORM INFORMATION SPECIFIC TO YOUR AREA ...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 800 AM EDT...1200 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT AND NOAA DOPPLER RADARS NEAR LATITUDE 25.7 NORTH...LONGITUDE 84.7 WEST. ISAAC IS MOVING TOWARD THE WEST-NORTHWEST NEAR 14 MPH...22 KM/H... AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE TODAY WITH A GRADUAL DECREASE IN FORWARD SPEED. A TURN TOWARD THE NORTHWEST IS EXPECTED BY TUESDAY. ON THE FORECAST TRACK...THE CENTER OF ISAAC WILL MOVE OVER THE EASTERN GULF OF MEXICO TODAY AND APPROACH THE NORTHERN GULF COAST IN THE HURRICANE WARNING AREA ON TUESDAY. MAXIMUM SUSTAINED WINDS ARE NEAR 65 MPH...100 KM/H...WITH HIGHER GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS... AND ISAAC IS EXPECTED TO BECOME A HURRICANE IN A DAY OR SO. TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 240 MILES...390 KM...FROM THE CENTER. THE ESTIMATED MINIMUM CENTRAL PRESSURE BASED ON DATA FROM THE AIRCRAFT IS 988 MB...29.18 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...MISSISSIPPI...AND ALABAMA...6 TO 12 FT * SOUTH-CENTRAL LOUISIANA...3 TO 6 FT * FLORIDA PANHANDLE...3 TO 6 FT * FLORIDA WEST COAST INCLUDING APALACHEE BAY...1 TO 3 FT * SOUTHEAST FLORIDA COAST AND THE FLORIDA KEYS...1 TO 2 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 OCCURRING OVER THE FLORIDA KEYS...AND SHOULD SPREAD NORTHWARD ALONG THE FLORIDA WEST COAST IN THE TROPICAL STORM WARNING AREA TODAY. TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE NORTHERN GULF COAST IN THE HURRICANE WARNING AREA LATER TODAY...WITH HURRICANE CONDITIONS EXPECTED ON TUESDAY. RAINFALL...ISAAC IS EXPECTED TO PRODUCE ADDITIONAL RAIN ACCUMULATIONS OF 1 TO 3 INCHES OVER CENTRAL AND SOUTHERN FLORIDA... WHERE ISOLATED MAXIMUM STORM TOTAL AMOUNTS OF 15 INCHES ARE POSSIBLE. TOTAL RAINFALL AMOUNTS OF 6 TO 12 INCHES...WITH MAXIMUM AMOUNTS OF 18 INCHES...ARE POSSIBLE IN SOUTHEASTERN LOUISIANA... SOUTHERN ALABAMA...MISSISSIPPI AND THE WESTERN FLORIDA PANHANDLE. TORNADOES...ISOLATED TORNADOES ARE POSSIBLE FROM CENTRAL FLORIDA THROUGH THE NORTHEASTERN GULF COAST TODAY AND TONIGHT. THE TORNADO THREAT WILL DIMINISH OVER SOUTH FLORIDA AND THE FLORIDA KEYS THIS MORNING. SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO AFFECT THE NORTHWESTERN BAHAMAS...THE FLORIDA PENINSULA AND THE FLORIDA KEYS DURING THE NEXT DAY OR SO...AND BEGIN TO AFFECT PORTIONS OF THE NORTHERN GULF COAST TODAY. PLEASE CONSULT PRODUCTS FROM YOUR LOCAL WEATHER OFFICE FOR MORE INFORMATION. NEXT ADVISORY ------------- NEXT COMPLETE ADVISORY...1100 AM EDT. $$ FORECASTER STEWART