Hurricane Isaac is moving northwestward toward the mouth of the Mississippi River. Flooding from storm surge and rainfall is expected. At 1:00 p.m. CDT the center of Hurricane Isaac was located by an Air Force Reserve hurricane hunter aircraft near latitude 28.4 north, longitude 88.7 west.
Isaac is moving toward the northwest near 10 mph, 17 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 as early as this evening.
Maximum sustained winds are near 75 mph, 120 km/h, with higher gusts. Isaac is a Category 1 hurricane on the Saffir-Simpson hurricane wind scale. Some additional strengthening is forecast until isaac makes landfall. Gradual weakening is expected after landfall occurs.
Hurricane-force winds extend outward up to 60 miles, 95 km, northeast and east of the center. Tropical-storm-force winds extend outward up to 185 miles, 295 km from the center. Tropical-storm-force winds are occurring at the mouth of the Mississippi River, where a noaa observing site at southwest pass Louisiana recently measured sustained winds of 60 mph, 93 km/h, and a gust to 76 mph, 122 km/h, at an elevation of 80 feet.
The latest minimum central pressure reported by the hurricane hunter aircraft was 975 mb, 28.79 inches.
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
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 are already occurring near the mouth of the Mississippi River, and will reach other portions of the coastline within the tropical storm and hurricane warning areas by late this afternoon. Hurricane conditions are expected to first reach the coast this afternoon.
Rainfall: Isaac is expected to produce total rainfall amounts of 7 to 14 inches, with possible isolated maximum amounts of 20 inches, in southeastern Louisiana, southern Mississippi, southern alabama, and the extreme western Florida panhandle. These rains could result in significant lowland flooding.
Tornadoes: Tornadoes may occur along the northern gulf coast today.
Surf: Dangerous surf and rip current conditions will continue to affect the Florida coastline and portions of the northern gulf coast for the next day or so.
Next complete advisory, 4:00 p.m. CDT.