On the 12th day before Christmas, when all throughout the Midwest
Forecasts were teasing snow, but some say it's still a guess.
Poetic cuteness aside, significant changes are coming to the weather pattern in the next two weeks that will have many snow lovers rejoicing. Others will just be bothered by the bitter cold. Nonetheless, chances of a white Christmas are more than twice as high (compared to normal) this year from the Upper Midwest to the Southern Plains.
Confidence is high in a colder-than-normal holiday period for much of the continental United States. Credible forecast models all project below-normal temperatures for the seven days surrounding December 25 in all locations east of the Rockies. However, they do differ in the extent and magnitude of extreme cold (compared to normal) during this period, which is also likely a factor of timing.
The three images below show 7-day average temperature anomalies from multiple runs of the GFS (American), ECMWF (European), and CFS (NOAA).
Temperatures are likely to be at least 10 to 15 degrees below normal from the Northern Plains to the Mid-South on or around Christmas Day. The numbers could be a lot colder than that in some areas, depending on snow cover and the track of multiple storm systems leading up to the holiday.
Here's an example long-range forecast for St. Louis from the GFS. The red box is drawn around a projected stretch of more than a week with subfreezing temperatures (day and night). According to this model, temperatures might even not top 20º for 72 hours straight!
Details on exactly how cold, and for how long, will become more apparent in the days to come. And those specifics will be significantly related to who gets snow or not.
Chances of at least one inch of snow on the ground (or falling) on Christmas Day are more than two times as high as the 30-year average across a large area of the nation's midsection. The interactive graphic below compares the historical probability (1981-2020) to my 2022 forecast.
Cities such as Oklahoma City, Little Rock, and Nashville that historically have less than a 1 in 10 chance of a white Christmas have elevated probabilities of 20 to 30 percent this year. Chances are also more than two times as high (compared to normal) across the Ozarks and lower Ohio River Valley.
The Arctic air that has been bottled up in western Canada since Thanksgiving is about to be unleashed by the powerful storm system moving across the nation this week. It will then be driven farther south by another storm system next week (Dec 19-23), with potentially a third cold front delivering the "knock out" blow of arctic air deep into Dixie.
At this time, significant differences and inconsistencies in model solutions preclude me from posting details on when, where, and how much snow or ice may fall during the week of Christmas. I will be posting numerous times on those details as they become available, including credible modeling and road condition data from my employer Baron Weather.
But for now, just know that this year's Christmas will likely be much colder than normal (and possibly white) from Montana to Mississippi. Temperature anomalies along the west and east coasts are less certain, but an active jet stream pattern is sure to deliver bouts of cold and snow in those areas as well in the coming weeks.
Snow will be sparse this Christmas east of the Rockies and south of I-90, and confidence is high that it will be unusually warm across the Southeast.
An onslaught of winter storms is likely to blanket much of the West with feet of snow over the next 12 days, especially in higher elevations. A white Christmas is also likely across the Northern Plains, Great Lakes, and inland areas of New England from one or two winter storms prior to the 25th.
Cities where snow on Christmas Day is not that uncommon, such as Denver, Des Moines, Chicago, Pittsburgh, New York and Boston, are unlikely to see the magical morning this year. And farther south, a pre-Christmas storm may bring the potential for heavy rain or thunderstorms from the Southern Plains to the Ohio Valley.
White Christmases have become less frequent across more than half of the nation, according to the new 1991-2020 climate normals.
There is some evidence climate change may be leading to warmer Decembers across the Southeast, making snow even more rare around the holiday. But the grinch to blame for this year's brown Christmas across the Midwest is an oscillating climate pattern known as La Niña. This cooling of the equatorial Pacific waters correlates with a wavier jet stream across North America that allows warmer air to surge north more frequently from the Gulf of Mexico.
Long range teleconnection data suggests a change in the pattern may allow colder air to penetrate deeper into the center and eastern parts of the nation by early January, but above normal temperatures (overall) are likely to continue in the Southeast for much of the winter.
