Southeast White Christmas? Part 1

southern snowstorm

We made a post the other day asking our followers when they had experienced their last White Christmas. Quite a few said never. A few others said back in 2010. Since many of our readers live in the Southeast, those responses weren’t all that surprising. Climatologically, having snow on the ground at some point on Christmas Day in the Southeast is exceptionally rare. Though, not impossible. . .

Download Southern Snow

In the coming days, we’re going to discuss those years that the Southeast had a White Christmas. They may be few and far between, but there’s value in revisiting the conditions and overall pattern that brought those rare snowy Christmases.

In this article, we will take a peek at how the pattern will likely evolve from now through Christmas Day. The overall pattern will remain quite progressive. Meaning, most regions of the U.S. will not remain under the influence of troughing or ridging for more than a few days at a time, if that. Unfortunately, such a setup favors lots of swings in temperatures.

For the first time in a while, temperatures MAY actually feel like Christmas on Christmas Day in the Southeast (give or take a day). Most model guidance agrees that a longwave trough will develop across the eastern half of the U.S., as ridging amplifies across western Canada and eastern Alaska. This pattern configuration favors anomalous warmth along the West Coast and into the Southwest. An anomalously cold air mass will sweep across most locations along and east of the Rockies. Even Florida could get in on this chilly air mass!

Projected departure from average temperatures Christmas Day morning

Most reading this post are already wondering, will there be any precipitation to go along with that brief shot of cold air in the Southeast? Maybe. The models indicate that a shortwave could become detached from the main flow and close off into a mid-level low as it approaches southern California and Baja California sometime next week. It would eventually get swept eastward by the southern stream. But features like these can meander for a while or even retrograde westward before getting reabsorbed back into the main flow. If the cold air intrusion is a strong as modeled, there could be about a two-day window, probably a day or two after Christmas, that any passing southern stream system could produce wintry weather for parts of the Southeast.  

Taking a look at projected 500mb geopotential height anomalies from the latest European model, it already has the longwave trough lifting northeastward by the 26th. At the same time, the closed low quickly moves eastward across Texas/northern Mexico. Residual cold air may hang around for a day or two tops, thanks to a departing surface high. This closed low, or any southern stream feature for that matter, would need to encroach upon the Mid-South and Southeast just as the long-wave trough begins lifting out.

Longwave trough lifts out the day after Christmas

If I were a betting man, I wouldn’t put anything down on a White Christmas happening across the Southeast at this time. Yes, there could be a very brief window for some action right after Christmas Day, but that window appears to be short. I’d certainly recommend not getting too hung up on model guidance in the coming days. Large inconsistencies may exist in how models handle any closed low that develops. But hey, a small chance is always something to watch!

Make sure you download our new mobile app that’s dedicated to providing you with detailed snow forecasts. Firsthand Weather recently launched a new mobile app called Southern Snow for iOS devices, which gives you a snow forecast for anywhere in the U.S! If snow starts showing up in the forecast, Southern Snow will let you know.

Download Southern Snow

Be sure to join us on the Firsthand Weather this Saturday at 2pm ET to get our official White Christmas forecast for the entire U.S.

Find out if you’ll have a White Christmas 2020 this Saturday on Firsthand Weather

The featured image used in this post is courtesy of Jennifer Kyzer, who captured a great shot of an early season snowstorm in SC in 2014. 

Everything You Need To Know About This Upcoming Winter Storm

As promised, I will keep this article brief and to the point. I have provided you with a lot of details on this upcoming winter storm already, but given that I have put out numerous updates on social media and the website at different times, I’m sure some of you have missed some important information.

Just to reiterate, a lot hasn’t changed with my overall forecast. This winter storm will be a significant winter storm for many across the United States, and it is definitely showing similar characteristics to some of the historic winter storms of the past. Overall, the forecast model guidance is in agreement other than on some of the specifics. The European model came in slightly north with its overall track and the GFS jogged slightly south. Surprisingly, I’m not in strong disagreement with the actual track that the models take this system. With that said, a jog as little as 25-50 miles north or south can make a HUGE difference, so be aware of that.

Okay, take special note of all the bullet points that I listed below:

• Snow/sleet will fall across northern Mississippi, eastern Arkansas, western Tennessee, and possibly as far south as extreme northern Louisiana on Friday. Many of those regions will start out as rain, but the transition to frozen precipitation will occur on Friday. Accumulating snow, which could be locally high in places, could fall especially across the northern third of Mississippi, the eastern third of Arkansas, and western Tennessee. Some accumulations will be possible in the other regions mentioned, too.
• A stout warm nose will be present just above the surface, extending across much of Alabama, Georgia, and eastern Tennessee. This will originally cause most of the area to start out as a cold rain, but a transition to snow/sleet will eventually occur. This will cut down on overall snowfall accumulations, but regions as far south as Atlanta and Birmingham could get some accumulating snow once the transition occurs. The heavier accumulations should occur just north of those bigger cities.
• As I have mentioned several times, there will likely be a cold air damming scenario that sets up as far south as northeast Georgia and Upstate and northern South Carolina. I expect a potentially significant ice storm (accumulations of ¼ inch of ice) to unfold across these regions starting on Friday. High ice accumulations will likely also occur across central and eastern North Carolina (likely excluding the near coastal regions). Forecast models tend to handle these scenarios horribly, but I have noticed that the guidance is handling this well today. Models could be slightly underestimating how far south this freezing rain falls. Please read the next bullet point.

Probability of greater than 1/4 inches of ice accumulations from Thursday night to Friday night:

Ice Storm Probability

• A transition to snow will eventually occur across most of the regions mentioned in the last bullet point, and the heavier accumulations will fall the farther north one goes. Snow could fall as far south as Midlands SC, but accumulating snow will be higher the farther north was one goes. I can’t even rule out some snow falling along the northern South Carolina coastal regions and near the North Carolina coast, as the cold air rushes in behind this system and moisture gets wrapped around the coastal low.
• The bullseye of very heaviest snowfall accumulations will likely fall from Kentucky into West Virginia and Virginia, including the Washington, D.C./Baltimore areas, southeastern Pennsylvania, including Philadelphia, Maryland, Delaware, and New Jersey. A region of heavy accumulations could also fall in western and north-central regions of North Carolina. This is going to be an extremely close call for New York City and Long Island, as a slight shift southward in track will remove NYC and Long Island from seeing as high of snowfall amounts. Many of these areas will be measuring snow in feet.
• Extreme southern regions of the Ohio Valley could get accumulating snow from this system, too.

Probability of greater than 4 inches of snow falling from Thursday night to Friday night (probabilities for amounts lower than 4 inches aren’t included):

snow prob map 1

Probability of greater than 4 inches of snow falling from Friday night to Saturday night (probabilities for amounts lower than 4 inches aren’t included):

snow prob map 2

I including every region that could possibly be impacted by this system. If you are on the edges of any of the regions that I just mention, be aware that a slight jog 25 miles north or south could be the difference between getting snow accumulations or very little snow at all. Also, as energy gets transferred to the coast, a dry slot will probably eventually set up somewhere. Keyword SOMEWHERE. Nailing that down will be pretty difficult, and wherever this sets up, this could cut down on overall accumulations for some of you.

Overall, I’m very pleased with the forecast. Hopefully this clears up some of your questions. Most of you are well-aware of how a slight change in track could change the forecast significantly for some of you, especially if you’re on those borderline zones. I will have continuous coverage tomorrow on this winter storm.

By the way, the image used as the feature image in this article was from last winter, taken in Grafton, MA by Sevag Sarkisian. I figured it was fitting for this article!