Communities from Lake Charles, La., to Mobile, Ala., are feeling the effects of Isaac with conditions deteriorating into Tuesday night.
Isaac showed signs of strengthening Tuesday morning with an eye forming and flight-level winds from aircraft increasing.
Isaac finally became a hurricane Tuesday midday after traveling thousands of miles since emerging off the coast of Africa.
Landfall along the southern coast of Louisiana is forecast by AccuWeather.com Tuesday night, considering that the center may brush the coast for a time while moving west-northwest.
A larger version of the latest forecast track map for Isaac (with times in EDT) can be found on the AccuWeather Hurricane Center.
Ironically, Isaac is expected to threaten lives and property along the northern Gulf Coast almost seven years to the date of Hurricane Katrina's devastating landfall.
As the AccuWeather.com Hurricane Center has been calling for since last Thursday, Isaac is expected to slam into the northern Gulf Coast Tuesday afternoon or evening as strong as a category 1 hurricane (with maximum sustained winds between 96 and 110 mph).
A developing split between high pressure over the interior United States is directing Isaac toward the Louisiana Coast Tuesday and Tuesday night.
Isaac will pound those in its path with destructive winds, widespread flooding rain and perhaps isolated tornadoes.
A track into southeastern Louisiana would spell trouble for New Orleans, Biloxi and Mobile in terms of storm surge.
Such a track will still cause water from Lake Pontchartrain to put stress on the city's levee system.
Winds circulating around Isaac would still funnel some water from the Gulf of Mexico directly into Mobile, via Mobile Bay.
With Isaac's path will drive significant storm surge around Houma and Morgan City, La. Tuesday night.
Those at risk of taking a direct hit by Isaac should closely monitor the progress of the storm, heed all evacuation orders and avoid flood-prone areas.
The dangers of Isaac will not end when the storm makes its final landfall. Flooding rain and the potential for isolated tornadoes will accompany Isaac inland through the South.
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Unionville, MD (1956)
A total of 1.23 inches of rain in one minute. World record for rainfall intensity.
Las Vegas, NV (1975)
Flash flooding stranded more than 100 motorists on the strip. Cars were swept from casino parking lots, killing 2 persons and creating $1 million worth of damage. In spite of the flooding most casinos remained open and one owner exclaimed: "We'll have to have floating crap games before we interrupt any of the gamblers!"
Valley City, MO (1984)
A total of 8.75 inches of rain from heavy thunderstorms.