What’s cold air damming and why it’s connected to the cold in North and South Carolina? (National Weather Service, University at Albany – Lance F. Bosart and Gerald D. Bell)

It’s the middle of April, and you’re probably wondering why it’s still cold. You are also probably wondering what “cold air damming” is, and why these two are related. 
 
When a high-pressure system moves to the east of a north-south oriented mountain range, a barrier jet will form behind the cold front and move towards the North and South Poles and the Equator. 
 
Bringing you back to science class, cold air is denser than warm air, and will sink to lower elevations faster. Take, for example, oil and vinegar. The vinegar is the cold air; it’s denser and will sink towards the bottom of the glass. Oil, on the other hand, is like the warm air; and will rise towards the top of the glass. The oil and vinegar stay separated until someone, or something shakes it up, just like the warm air will remain on top of the cold air. Even though we really want the cold air to get pushed out and away, in a situation like cold air damming, it’s not that easy. 
 
The cold air sits at the surface, keeping areas like the North and South Carolina and Virginia in a non-stormy cold and cloudy area. The cold air essentially has nowhere to go because of the Appalachian Mountains that stretch north-south. The peaks of these mountains are at a higher height, that cold air cannot rise above. 
 
Cold air damming is most commonly known to affect places like the Carolinas and Virginia in the U.S. But the south of the Alps in Italy and near Taiwan and Korea in Asia are also prone to cold air damming. 
 
One of the simplest ways to get rid of cold air damming is through cold air advection. Cold air advection allows cold air to flow in weakening the warm and cold boundary layer in the atmosphere. Just like in the example above, we needed something to shake up the oil and vinegar so that they weren’t separated. In this case, the cold air advection is that something that comes in and “shakes up” the temperature inversion, allowing solar heating which ultimately warms up the surface. 
 
To learn more about other neat educational topics in meteorology, be sure to click here!

© 2018 Weather Forecaster Allison Finch