East Coast Weather Today: Cold Air Damming Brings Sudden Chill

East Coast – A noticeable fall chill has spread across parts of the eastern United States as a weather pattern known as cold air damming funnels cooler air southward along the Appalachian Mountains.

According to the National Weather Service office in Greenville-Spartanburg, cold air damming, commonly called CAD, is responsible for a sudden change in temperatures Wednesday. Cooler air is moving south and becoming trapped against the eastern slopes of the Appalachians.

The setup typically develops when cold, stable air moves down from the Northeast and becomes wedged against the mountains. Because the dense air has difficulty crossing the Appalachians, it can remain entrenched along the eastern side of the range.

The National Weather Service graphic shows the cold-air wedge extending from the Northeast through the Mid-Atlantic and into portions of the Carolinas and Georgia.

The pattern can also produce major temperature differences over relatively short distances. Communities in the Appalachian foothills can remain significantly cooler than locations farther west in the mountains or east toward the Coastal Plain.

Weather conditions can become damp as well. The National Weather Service notes that warm, moist air moving over the shallow layer of cooler air can produce clouds and precipitation.

For residents across affected portions of the East Coast and Southeast, the setup means conditions may feel considerably more like fall despite recent warmth.

Drivers should also be prepared for potentially damp conditions and reduced visibility where low clouds, fog or precipitation develop.