A cool start to the week is ahead for most of the US East Coast due to cold air damming, but as high pressure moves off to the east while a ridge of high pressure, above average temperatures will finally dominate most of the Eastern third of the country.
Let’s explain this cold air damming, which will take place Sunday into Monday before beginning to weaken but will remain on Tuesday. Cold air damming, which can also be known as a wedge, occurs when high pressure positions itself over the Northeast, drawing in cooler air from the north and pulling it southward east of the Appalachians. These events can sometimes be hard to predict in the Southeast because it depends on how strong the wedge is. For some instances, the cool air associated with the wedge can get as far south as the eastern Gulf Coast.
So on Sunday, high temperatures up and down the East Coast will be up to 20 degrees below average. The most intense negative anomalies will be found in the Carolinas, but it will be cooler than average for a widespread region, extending from most of Georgia and the Carolinas up through the Northeast and back into the Great Lakes, Midwest, and Northern Plains.
Temperatures will moderate across the Northern Tier on Monday, and some areas in the Great Lakes region and the interior Northeast may actually warm up to a few degrees above average. Where the warmest air relative to average will be, however, will remain in the Southern Plains. Meanwhile in the Southeast, this cold air damming event will be at its peak with below average temperatures working as far south and west as Mississippi and the Florida Panhandle. Much of the US East Coast will experience temperatures 10-20 degrees below normal.
Beginning Tuesday, the wedge will begin to weaken. This will allow for near-average temperatures to work into Alabama, the Florida Panhandle, and Georgia. New England will begin to feel those warmer temperatures where highs will be right around average, which is very welcome, because it’s be a cool month. The worst of the cold will be in the Mid-Atlantic while the Great Lakes and the Mid-Mississippi Valley warm up.
Wednesday will be the turning point for many locations. The wedge will break free, and warmer temperatures will invade the Southeast. Temperatures will generally be 5-10 degrees above average throughout the region. It will feel quite nice in the Great Lakes region and Ohio and Tennessee Valleys as well with those milder temperatures. The Northeast coast, however, will remain up to 5-10 degree below average.
By Thursday and Friday, cooler temperatures will begin to invade the Midwest and Great Lakes while the US East Coast experiences temperatures 10-15 degrees above average. Unfortunately, cooler temperatures will return to the East as we begin the month of April next weekend.