Here is the current AccuWeather composite radar at 7:45am CDT. I have added arrows to show the direction of movement of the rainfall. In this case, heavy rain keeps falling over the same areas, adding up to some tremendous amounts.
The flooding threat seems to be increasing from Tropical Storm Lee. Here is an AccuWeather display of estimated rainfall from the NWS radar in New Orleans:
|click to enlarge any graphic|
Already rainfall amounts of 4″ or more (red) are common in southeast Louisiana. And, the 4″ amounts (note slightly different color scale) are being experienced near the AL-FL border.
While Lee is expected to have sustained winds of 65 mph (with gusts to 75 mph) at landfall which will cause trees to be uprooted with power failures; extensive, widespread flooding will be the worse problem. Why? Because even though 2-6″ have already fallen, storm total rainfall forecasts have been revised upward.
An additional 19″ of rain is forecast for New Orleans with ≥15″ for Mobile, Gulfport and Hattiesburg! People living in these areas should be prepared for major flooding and evacuations.
And, the threat doesn’t stop in the South.
The bright yellow is 7″ which includes Birmingham and Asheville. That’s plenty of rain to cause at least some flooding. But, as Lee merges with a cold front, the heavy rains continue into the Northeast with about 7″ forecast around Harrisburg.
Here is a map of rainfalls for the last two weeks that includes the rains from Irene:
Where the heavy rains from Lee overlap the areas with saturated soils from Irene, major flooding may redevelop.