Doppler estimated 48-hour rainfall totals in South (National Weather Service)

Over the past two days, the Deep South has been deluged by up to 5-10 inches of rain, leading to flash flooding in parts of Mississippi and Alabama.  This is part of the same storm system producing a chilly rain in the central and northern Mid-Atlantic.

In the South, some of the heaviest rains fell Sunday and Sunday night. The Weather Channel reports:

Hardest hit was parts of northern Alabama, including the Birmingham metro area, where evacuations and high-water rescues were prompted.

In Pelham, just south of Birmingham, more than 4 inches of rain fell from 7 p.m. Sunday to 7 a.m. Monday.

In Mississippi, a 9-year-old girl is missing and feared swept away by floodwaters in Yazoo City.

Here’s some video of the Alabama flooding:

Firefighters save a stranded driver after flash flooding in Birmingham, Ala., overtakes city streets. (Reuters)

Some flooding has spread into Georgia today.

The culprit for the extreme rainfall is low pressure in the Tennessee Valley which has acted like a pump, drawing rich tropical moisture from the Gulf of Mexico northward.

The map below shows the area of low pressure over Kentucky and sprawling zone of elevated moisture to its east and southeast.  Levels of precipitable water, a measure of the depth of rain if all humidity in the air column were to condense, are in the 1.5-2 inches rain – which is very high.


RAP model simulation of low pressure in the Tennessee Valley drawing northward very high precipitable water levels from the Gulf Coast to the southern Mid-Atlantic (WeatherBell.com)

As this area of low pressure jogs to the northeast towards the eastern Great Lakes, the deep plume of moisture will push off the eastern seaboard, ending the heavy rain threat by late tonight.  Before it does so, heavy rains are expected from northern Florida to eastern North Carolina, along with the possibility of severe thunderstorms.  Already, strong storms have erupted in northern Florida and eastern Georgia where a tornado watch is in effect through 4 p.m.