White Christmas Forecast 2020

Now that we’re less than 7 days from Christmas, our Southern Snow app will provide you a super-localized forecast on the upcoming snow potential this Christmas week. Our written forecast discussions, such as this one, should provide a nice ‘heads up’ that may or may not be currently reflected in the daily forecasts. You sort of get the best of both worlds if you have the app.

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High probabilities

A strong shortwave will enter the Pacific Northwest on Tuesday and sweep across the Rockies on Tuesday and Wednesday. This system will add to existing snow cover across the Cascades, the northern Sierra Nevada region and most of the Rockies, ensuring a White Christmas.

Snow cover from last week’s nor’easter will begin rapidly melting on Christmas Eve and Christmas Day. However, areas that picked up feet of snow across the Mid-Atlantic and Northeast will still have snow cover from the event, even at lower elevations.

Moderate probabilities

The upper Midwest and the Great Lakes region will have several opportunities for snow in the coming days. A weaker system will pass through the area early this week, and a stronger storm system will set the stages for lake-effect snow on the backend on Christmas Eve and Day.

The same mid-week system has the potential to bring noteworthy snow accumulations to areas along and west of the Appalachians, along with western areas of New York.

Possible probabilities

One could make the argument that some areas included in the possible probabilities category should eventually get bumped up to moderate chances. I concur. As one shortwave swings across the Midwest and Great Lakes mid-week, another wave will dig southeastward into the Plains and mid/lower Mississippi Valley. As a result, a second surface low could develop farther south early Christmas Day, bringing snow chances as far south as eastern Tennessee and the northern Gulf coast states.

The air mass behind the advancing strong cold front will be very dry, so there remains much uncertainty on moisture availability. Nonetheless, snow-to-rain ratios will be high behind the front, so even a little moisture and lift would do the trick. Climatologically, these setups have a relatively high probability of being a bust for snow, especially farther south. However, if I see that short-range guidance supports higher totals, I’ll probably need to bump up probabilities to a moderate for some.

Before coming eastward, the same wave will have the potential to produce accumulations east of the Rockies across Colorado, Wyoming, and into parts of the Northern/Central Plains before Christmas Day. It’s quite likely some of those areas will get pushed into moderate probabilities in a subsequent update by Firsthand Weather.   

2020 White Christmas forecast
2020 White Christmas Forecast

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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. . .

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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.

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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.