Dam-Breaking High Wind (40-70 mph Gusts) Event…Evolution of Event on NAM Model

Thursday night into Friday, the dam of cold air is going to break over the Appalachians into the Mid-Atlantic with a high wind event I call “Dam-Breaking High Winds.” This type of event occurs when the cold air builds up on he west slopes of the Appalachians and eventually break over the mountains into the Mid-Atlantic with wind gusts 40-70 mph.

Low topped thunderstorms may be associated with the event that only enhance wind gusts. In addition, high winds aloft can be brought down to the surface in sudden gusts that cause power outages and damage to trees and buildings.

Midwest Snowfall is About

Ratios and Temperatures

The event that unfolds Thursday night into Friday morning is a classic one as temperatures will be in the 70s on the East slopes and in the 30s on the West slopes. That cold air will rush over the mountains at night, slamming the big cities with high wind gusts of 40-70 mph.

Below are several animations showing the event in regards to the temperatures, squall line, and wind gusts.

Temperatures Showing the Cold Air Pooling then Coming over the Mountains.


Squall Line that Forms


Wind Gusts



Posted by

Expert Meteorologist with over 30 years of weather forecasting and blogging.

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