COLUMBIA, S.C. — If you live in the Midlands, or anywhere across the Carolina's, you have probably heard the term "the Wedge" talked about in your weather forecast a few times. It's a weather phenomena that occurs in the Southeast and can leave the area under a mixed bag of conditions depending on the time of year.
This setup is forecast to occur again on Tuesday, keeping our temperatures low and providing a small chance for rain, but what exactly is the Wedge?
Meteorologists use the term "Cold Air Damming" when talking about this specific setup, as cold air gets pushed, or dammed, up against the eastern side of the Appalachian mountains. When looking at a pressure map, it is easy to see how the nickname of the Wedge was created. Isobars, or lines of equal pressure, get wedged up against the mountains.
The setup all starts with an area of high pressure situated in the northeastern United States. Air spins clockwise around high pressure, meaning for us in the Carolina's that air is typically coming from the northeast. This cool northern air continues to funnel into the Southeast at the surface and gets trapped up against the Appalachian Mountains, making conditions pretty chilly for us at home.
In the upper atmosphere, winds continue to blow from the south, bringing in warmer air above the cooler air at the surface. Cloudy conditions are often created from the warm, moist air aloft.
Thus, cold air damming tends to create chilly temperatures for us here in the Midlands, while keeping skies fairly cloudy.
For forecasters, this setup can become tricky to forecast when increased moisture is present and some form of precipitation will likely occur. The depth of the layer of cold air can dictate whether someone sees rain, freezing rain, or snow.
Thankfully, we are not concerned with any precipitation type forecasts this time around, as temperatures are still in the 60s and 70s. However, this setup could be the deciding factor once Winter rolls around on whether or not we see any winter precipitation here in the Midlands.