August 31, 2021

Ida's Remnants Are A Flash Flood Threat In The Mid-Atlantic And Northeast This Week

The remnants of once-powerful Hurricane Ida will bring a threat for flash flooding and tornadoes to much of the eastern U.S. over the next couple of days.

While the storm's winds are a mere shadow of their 150 MPH fury when the storm made landfall in Louisiana on Sunday, the system is still a major rainmaker and will lead to a threat for tornadoes through midweek.

Ida's remnants will pass over the Tennessee Valley Tuesday and Wednesday, reaching the Mid-Atlantic and Northeast by the end of the week.

A trough moving over the Great Lakes will catch up with Ida's remnants by the middle of the week. This trough will help the system redevelop into an extratropical cyclone, or your typical, everyday type of low-pressure system.

The combination of Ida's tropical moisture and all the extra lift from the trough and developing surface low is a recipe for very heavy rainfall. It's the atmospheric version of wringing out a soaked washcloth.

Source: WPC

Right now, the Weather Prediction Center has a moderate risk for excessive rainfall (read: flash flood potential) across a wide swath of the Mid-Atlantic and parts of the southern Northeast. 

The agency's latest rainfall forecast shows widespread totals of 3-5 inches falling along the path of ex-Ida. Locally higher totals are possible, especially where training thunderstorms produce high rainfall rates.

Stay alert for flash flooding during and after heavy rainfall. If any of your daily routes are prone to flooding, map out an alternate route ahead of time so you can avoid danger.

Many people die every year when they drive into a flood and drown. It's impossible to tell how deep the water is until it's too late, and sometimes there's not even a road under the water anymore. 

Flooding won't be ex-Ida's only hazard. There's still enough wind shear on the eastern side of the system to allow thunderstorms to begin rotating.

We'll see a tornado risk across parts of the southeast and Mid-Atlantic over the next couple of days. This risk is greatest in Alabama, Georgia, and the Florida Panhandle on Tuesday, but tornadoes are possible as far north as the Delmarva Peninsula through Wednesday.

Tropical tornadoes happen quickly, sometimes with reduced tornado warning lead time. Make sure your cell phone's wireless emergency alerts are activated so you can receive a tornado warning the moment one is issued.

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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I contribute to The Weather Network as a digital writer, and I've written for Forbes, the Washington Post's Capital Weather Gang, Popular Science, Mental Floss, and Gawker's The Vane. My latest book, The Skies Above, is now available. My first book, The Extreme Weather Survival Manual, arrived in October 2015.