|AccuWeather Global Weather Center – December 1, 2021 – With a growing number of places across the United States getting their first snowflakes of the season, it’s once again that time of year to break out the hot chocolate and look ahead at the chances of a white Christmas across the contiguous U.S.
A climate pattern well-known for bringing precipitation to the northern tier of the country may tip the scales on which areas get a white Christmas or just a handful of flurries — if that — this year.
To forecast what kind of weather the different regions of the U.S. will have a month out from the big day, AccuWeather’s team of long-range forecasters, led by Senior Meteorologist Paul Pastelok, looked to key patterns that could favor snow in time for the holidays this winter.
La Niña, a phase in which sea surface temperatures in the equatorial Pacific Ocean drop to lower-than-average levels for an extended period of time, was one such pattern that played a major role in drawing the map. The big thing to know about La Niña is that it tends to steer storms northward, cutting the southern portion of the U.S. off from moisture.
With the La Niña phase in place, areas across the Northwest, upper Plains and interior Northeast will have a higher probability than average of having a white Christmas. However, the same cannot be said for the lower half of the nation.
AccuWeather’s criteria for a “white Christmas” centers around having at least an inch of snow on the ground for the holiday — a qualification that is difficult for many warmer locations in the U.S. even without a La Niña pattern.
“It’s the southern areas that may be in hurting shape because La Niñas are usually northern track storms, and if we have this lull in December, we may have some issues across some of the southern tier,” Pastelok said, suggesting that Americans living across lower latitudes and dreaming of a white Christmas shouldn’t expect those dreams to become a reality.
In addition to the storm track preventing snow from reaching places to the south, chances of snow on or around Christmas are lower across the mid-Atlantic, Southeast and southern Plains as temperatures just may not be cold enough for snow to fall and remain on the ground.
Even areas that historically have a less than 5% chance for snow on Christmas Day will have a lower probability for snow compared to normal. Areas with these extremely low chances stretch through the Gulf Coast and up the Eastern Seaboard and into southern New England. While the Northeast is forecast to have below-average chances of a white Christmas, probabilities lean closer to normal, and snow is likely to be on the ground in higher elevations.
“We’re actually kind of in that normal zone for [the Northeast] just in case we get one of these sneaky, late-December systems coming in there,” Pastelok said. “But I do feel like the probability of a white Christmas in Boston, New York, D.C. and Baltimore is slightly lower” this year.
NYP2000123006 – 30 DECEMBER 2000- NEW YORK, NEW YORK, USA: Snow covers the trees that lead up to the main Christmas tree in New York City Rockefeller Center December 30, 2000. New York received a foot of snow from a storm described as a “snow bomb”. bc/ep/Ezio Petersen UPI, UPI / Ezio Petersen
With the La Niña phase favoring a northern storm track, the southern branch tends to get cut off most of the time, Pastelok said, but he noted that there have been some exceptions. During the winter of 2020 into 2021, systems early on dipped into the South with some reaching all the way into Mexico. However, Pastelok said that this year, conditions are set up differently and the Southern states should have “more of a traditional La Niña” pattern, at least during the first part of the season.
The same applies to the southwestern U.S., and fewer storms could greatly impact not only ski resorts but also areas that rely on a healthy snowpack to ease drought conditions.
The American Southwest has endured a long, ongoing drought stretching from Southern California into New Mexico. Not even the Great Salt Lake has escaped the impacts of the intense heat and lack of rain over the decades.
“The upper-level high has been pretty pronounced across the Southwest, and that has caused temperatures to come up. It’s caused a lot of dryness to return to these areas,” Pastelok said. Forecasters believe that this high will pulsate throughout the winter season, allowing the storm track to drift southward from time to time into Central California, the central Rockies and Colorado this winter season. However, many of the same areas have historically had a less than 5% chance of getting snow over Christmas — and those chances are expected to be even lower this year.
As of Dec.1, Denver, Colorado, has recorded 224 consecutive snowless days as warm and dry conditions continue across the area. The last time the Mile High City received measurable snow was on April 21, 2021. On average, the Denver International Airport measures 9.1 inches of snowfall during the meteorological fall, and the city typically receives its first measurable snow by Oct. 18.
In contrast, areas in the Northwest — a region that has also been struggling with drought — are likely to have higher-than-normal chances of snowfall, especially in the higher elevations.
Oregon and Washington state in particular have endured the intense repercussions of drought, especially after the deadly heat wave that killed at least 96 people in Oregon alone during June, The Guardian reported.
Due to the La Niña storm track, however, they are two states most likely to have a higher-than-normal chance of a white Christmas, along with western Idaho and portions of Northern California and Nevada. Any precipitation would be welcome in these specific parts of the West if only to buffer the areas from drought conditions during the upcoming summer.
The Midwest will be more of a mixed bag in terms of what to expect for the holiday.
A swath of the region across the central Plains into the Great Lakes area is likely to have a higher chance than normal to get a white Christmas, including cities such as Omaha, Chicago and Cleveland.
However, moving farther south, the chances of a white Christmas start to become slim to none. Rain may overtake snow through Christmas in the Tennessee Valley to the lower Ohio Valley, according to AccuWeather forecasters, making it difficult for any snow that does fall to remain on the ground.
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