Daily downpours keep flash flood risk high in Southeast

Parts of the South have been waterlogged this month, with several cities reporting rainfall amounts more than 200 percent above normal since Sept. 1.

The threat for flash flooding will continue across the Southeast less than a week after Nicholas brought excessive rainfall to the region, AccuWeather forecasters say.

Not only were areas along the Gulf coast inundated with downpours by Nicholas, but high pressure over the Northeast and near Florida has allowed moisture from the Atlantic Ocean and the Gulf of Mexico to stream into the Southeast over the past few days.

This weather setup resulted in major flooding in Alabama Saturday afternoon and 4 to 6 inches of rain that fell in 24 hours across Middle Tennessee. Daily, heavy downpours are expected to continue across the Southeast through the middle of this week.

"Showers and thunderstorms, that could be heavy at times over the Southeast will be in the region in the coming days, but anywhere that does see these storms will have a continued flooding risk that could cause travel delays and localized flooding," AccuWeather Senior Meteorologist Alan Reppert said.

Several locations across the South have already picked up their fair share of rainfall since Sept. 1, leaving them waterlogged. New Orleans reported over 7 inches of rain since Sept. 1, which is nearly 200% of the normal rainfall for this time period. Mobile, Alabama, is another city that has been left waterlogged since Sept. 1, where 209% of the normal rainfall has fallen.

With more rain on the horizon, many cities in the South will remain on alert for the continued threat of localized flash flooding through Tuesday in the Mississippi River Valley and farther east through Wednesday.

"These storms will be drenching at times as they will have moisture from the Gulf of Mexico and Atlantic to work with, leading to the continued threat of localized flash flooding," Reppert explained.

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High pressure in the Northeast and near the Florida Peninsula will allow for tropical moisture from both the Atlantic and the Gulf of Mexico to filter into the Southeast, pausing the normal west-to-east progression of storms. Strong areas of high pressure such as this can essentially act as a roadblock in the atmosphere, resulting in a seemingly never-ending stormy pattern.

An uptick in humidity levels across the Southeast thanks to moisture feeding into the area from the Gulf of Mexico and Atlantic will give thunderstorms plenty of fuel to produce heavy downpours.

AccuWeather meteorologists warn that when heavy downpours persist over the same area, flooding in farm fields that could lead to crop damage is possible along with ponding on roadways.

Experts highly caution that travelers never attempt to drive through flooded roadways, because cars could stall or be swept away by floodwaters, resulting in a potentially deadly situation.

There is relief on the horizon for those in waterlogged cities and towns across the South as a cold front is expected to arrive in the East by midweek.

"The flood threat will continue into midweek until a cold front sweeps through the southeast by Wednesday night, leaving cooler and drier air across the region by Thursday," Reppert said.

Dry, less humid air and much cooler weather for some are expected to stop the threat of daily downpours across the South as the week draws to an end. Dry conditions will allow for any cleanup efforts to get underway from any flooding communities or towns. Waterlogged cities will have the chance to dry out and residents can begin working on outside projects as high pressure moves into behind the front.

High pressure will continue to keep much of the South dry next weekend and potentially into early next week.

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