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. . .
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!
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.
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!
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Since many of you asked for me to do this, I decided to make a White Christmas probability map. Now, probability maps can be hard to interpret, so let me briefly explain everything a bit further. Climatologically, most Christmas snows are confined to the northern U.S. and the mountains out west. Because of the coming pattern flip that will significantly increase the United States snow chances (even unusually far to the south), I am going against climatology and am much more bullish on widespread snow cover across the U.S. this Christmas or right around that timeframe.
For those of you that follow my forecasts closely, I typically try to identify any pattern change or potential storm development several weeks out, and then I fine-tune those forecasts as we get closer to the event. We’re still over 10 days away from Christmas, and while I am confident that a winter storm will occur right around Christmas, it’s very difficult to determine if it will actually happen on Christmas Day, or where it’ll track.
Right now, snow cover extent across the United States is very low, but that will begin to change as we get around Christmas and beyond. Putting together this probability map was particularly tricky because Christmas will be the timeframe that the pattern will actually be flipping back colder, similar to what we had in November except colder. As any meteorologist knows, saying that a storm is going to happen on an exact day is difficult beyond five to seven days, but identifying a pattern change beyond seven days can be done and can give some strong hints as to what should be expected later down the road.
White Christmas 2014 Probability Map
Because I am expecting a winter storm right around Christmas and a potential pre-Christmas storm next weekend, you will notice that I have most of the U.S. with a chance at having a white Christmas. What may even be more surprising is that I have a 15 to 30% chance of a white Christmas across a large region of the southern U.S., which is unheard of for this time of year. The reason I did this was because of the potential storm around Christmas, but if for some reason I see that this storm will occur right after Christmas (say the 26th or 27th), then I will cut back those chances in my future probability map that I’ll be putting out next Sunday. Typically, the southernmost regions in the 15 to 30% zone have less than a 5% chance of seeing a white Christmas.
If you missed my detailed article yesterday explaining all of my predictions for this timeframe, please click here. Below, I decided to post the historical chances of a white Christmas, so as you can clearly see, I’m definitely going against climatology this year if you compare it to my map above.
Historical Chance of a White Christmas
I will continue to keep you updated on the winter storm potential around Christmas. Please like and follow Firsthand Weather on Facebook and Twitter.
We’re less than two weeks away from Christmas, and everyone is wanting to know if they’re going to have a white Christmas. It’s always difficult to determine if you will have snow on the ground in YOUR backyard on Christmas Day until we get much closer to the 25th, but what I can tell you is whether or not the overall pattern will favor a winter storm developing over a particular region. My confidence continues to grow that a large area of the United States will be under snow cover this Christmas, and that is taking into account that most of our snow cover has melted since the big November freeze. I will even go as far to say that regions that typically never see a white Christmas could have one this season. Please don’t misunderstand me because regardless of how favorable the overall pattern may be, there are going to be some that will be happy and some that will be disappointed on Christmas morning.
The Current Pattern and How Things Are About To Flip:
Relatively speaking, much of the United States has had temperatures closer to average or just above average, which is a 180 degree flip from what most of us experienced in November. Some areas along the East Coast have still held close to average, even below average in places, while temperatures have been above average further west. This has definitely not been the blowtorch December that many were predicting, and there are signals that are strongly hinting at a pattern flip taking place around Christmas. That goes right in line with my thinking that regions across the central and particularly the eastern United States will be flipping back cold after mid-December.
While the pattern starts to make the flip back to a colder pattern, there is going to be a lot of volatility in the weather, and despite not having a locked-in cold pattern yet, you can still get a lot of active weather, including winter storms.
Most of the United States has been getting its air from the warmer Pacific this month, whereas most of our air was coming directly from the Arctic last month. As most of you are well aware, California and up the West Coast has become extremely wet, and this is due to a strong Pacific jet stream that has been bringing a steady flow of moisture over the region. This strong Pacific jet stream that set up as predicted is important because it will bring in the needed pieces of energy from the Pacific to increase the winter storm potential further east and south throughout the winter months. This is one piece of the puzzle that needed to occur to bring a wetter and potentially snowier winter across the South, and we are seeing that setup already.
Once we get the needed blocking over the Arctic and Greenland, that will start to push that Arctic air south over the United States once again. The polar vortex is still very strong and well-established over the Arctic, and eventually, that will likely once again weaken/split and become displaced. For those of you that don’t know, the polar vortex is a low pressure area that is located in the upper levels of the atmosphere. Strong winds rotate cyclonically around this low over the North Pole keeping all of that Arctic cold bottled up to the north, but this vortex can weaken and split, displacing that colder air to the south. I am expecting that to occur as we get further into winter, and this upcoming January is already starting to look similar to what occurred last January.
If you didn’t understand all of the explanation above, that is completely fine! Now I’m about to tell you what to actually expect, although I will have to explain some of the meteorology behind everything. I’ll try to keep things simple.
Pre-Christmas Winter Storm Potential:
Before I get fully into this discussion, please understand that this is NOT the potential winter storm that I have been predicting for a while now on Christmas or around then. This is ANOTHER winter storm potential that could take place right before Christmas, if and only if, everything comes together just right. Someone will likely get a winter-type storm, but it’s a matter of where. Let me explain.
There is a piece of energy that is currently moving over California, and it is going to come east tonight and tomorrow. This is going to cause a surface low to develop and then move over the Southern Plains tomorrow and eventually push northeast over the Great Lakes early in the week. This will bring rain to the Southern Plains (maybe even storms) and eventually rainy conditions further north and east. Now let me explain why all of this matters for the pre-Christmas winter storm potential for next weekend.
This low pressure system that develops and moves over the Southern Plains is going to eventually make its way to the Northeast and then strengthen over northeast Canada. Now around mid-week, there is going to be another system move into California and track across the Southern U.S. Because the overall pattern is not necessarily favorable for winter storms developing and tracking across the Gulf Coast states just yet, we’re going to need that surface low pressure system to strength over northeast Canada which would allow for a strong high pressure to develop and strengthen over the Northern Plains and Great Lakes and further southward. If this occurs, then the system pushing into California would be forced further south once it moves eastward, and because of this, a surface low could develop across the Gulf Coast states next weekend around the 21st. Because of the placement of the low and high pressure systems further north allowing cold air to funnel southward, this could get VERY interesting for the Gulf Coast states and up the East Coast. Remember, storm systems take the path of least resistance.
This is the pre-Christmas system that will be moving into California that needs to be watched closely.
This is one of those situations where everything would just have to play out perfectly. If it doesn’t, then that storm system is going to move further north and would bring wintry weather further north. Because we don’t have the cold pattern set up over the region just yet, the southern regions would have to depend on sufficiently cold air to funnel down south due to the high pressure system to the north.
I hope that I didn’t get too complicated, but what I’m saying is that I’m not ruling out a potential winter storm for parts of the Gulf Coast states this weekend and then eventually areas northward up the East Coast. Parts of Tennessee, North Carolina, Virginia, and likely northward would for sure get snow with a more southern track storm. The track of this system could also favor snow and/or ice even further south across parts of the Gulf Coast states, possibly including parts of Alabama, Georgia, South Carolina, and maybe other states. Again, details are super iffy and subject-to-change. In this setup, everything has to come together just right! I can’t stress that enough so I hope you sense my uncertainty and lower than normal confidence.
Christmas Eve/Day Winter Storm Potential:
This may sound weird to you, but I am more confident about a winter storm developing on or around Christmas Eve or Christmas Day than I am regarding the potential storm that I just discussed above. The reason for this is that our pattern is going to likely flip right around Christmas, and the overall pattern is going to support cold across the central and eastern United States. The necessary blocking is going to start to set up over the regions that I mentioned in the beginning of this article, and that in return is going to favor storminess across the southern states and up the East Coast. Any energy that develops and moves into California will then be in a favorable environment further east to develop and strength. Under such an active pattern, you can have northern pieces of energy phase with southern pieces of energy. In simple terms, when you have two smaller systems combine into one big system, you get a stronger system.
Once again, another storm system is supposed to move into California before Christmas and track eastward. Again, the overall pattern will support this system staying south, and even if it were not to phase exactly right with a northern branch system, areas across the Southern U.S. has the potential to get snow and/or ice around Christmas.
This is the second system that could bring a big winter storm on Christmas Eve/Christmas Day. Notice the first pre-Christmas storm system on the East Coast.
From what I can tell, I see this potentially being a big winter storm for the Gulf Coast states and eventually up the East Coast on Christmas Eve/Day or right around then. Even the Southern Plains need to keep an eye on this system before it moves east, but my primary focus is on the Gulf Coast states and East Coast. The track of this system and the amount of cold air available (which could be plenty sufficient) would support wintry weather pretty far south. No, if you’re in Miami, FL, I’m not saying you’re getting snow, but what I am saying is that some regions that hardly ever have a White Christmas could get one this year.
Please understand that just because you’re in the South doesn’t mean you’re going to get snow or ice on Christmas. The goal of this article is to make you aware that the overall pattern favors a White Christmas for many. Some of the methods that I use to come up with my forecasts (that don’t rely on model guidance) also are strongly hinting at a winter storm around Christmas. Right now, everything seems like it could come together.
The details will become more fine-tuned as we get closer to each potential system. My goal is to always make you aware that there are certain limitations in weather forecasting, but I’m not going to sit here and keep all of this to myself just because we’re still a decent ways out. I hope this article gave you a good understanding of what is going on, and why I am making these predictions. If there is enough interest, I may come out with one of those “what are your chances of seeing a White Christmas” maps sometime this week. Let me know if that’s something that would interest you.
I’ll continue to keep you updated on the latest through this site. I will be putting out daily updates on Facebook and Twitter, so be sure to like and follow both of those pages. It’s important that you follow my forecasts closely over the next couple of weeks because changes will have to be made due to the volatility of the current pattern.