NWS Mesoscale Discussion: Flash Flooding Likely This Afternoon As Rain Expands

Heavy rain is expected to continue through the rest of the afternoon and into this evening across parts of Kentucky, Tennessee, and the central and southern Appalachian Mountains, including portions of western North Carolina.

The biggest concern is flash flooding, not severe thunderstorms.

A slow-moving weather system spinning over Kentucky is acting like a trigger, allowing showers and thunderstorms to repeatedly develop over the same areas. Because these storms are moving very slowly, they can dump a lot of rain in a short amount of time instead of quickly moving away.

Rainfall rates of 1 to 2 inches per hour will be common in the heaviest storms, and a few locations could see more than 2 inches in a single hour. By the time the rain ends, some communities could pick up 2 to 4 inches of rain, with isolated totals over 4 inches where storms repeatedly track over the same location.

This setup is especially concerning because many areas don’t need much additional rain before creeks, streams, and low-lying roads begin to flood. Some locations have already received several inches of rain earlier today, leaving the ground unable to absorb much more water.

The storms are not expected to organize into a widespread severe weather event, but they can “train,” meaning multiple storms move over the same area one after another, or “backbuild,” where new storms continue to develop over the same location. Both of these patterns greatly increase the risk for flash flooding.

If you live in a flood-prone area or near small streams and creeks, keep a close eye on the weather through this evening. Never attempt to drive across a flooded roadway—just a small amount of moving water can sweep away a vehicle, and it’s often impossible to tell how deep the water is.

The flash flood threat is expected to continue through this evening before gradually decreasing after sunset


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Published by wxchristopher

Chief Meteorologist

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