A large, dynamic storm system will bring multifaceted impacts to the central and eastern U.S. this Christmas, including heavy snow, blizzard conditions, and ice for portions of the Central Plains and Upper Midwest with heavy rainfall and the risk for flash flooding in the Southeast.
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As an upper level low deepens over the Central Plains, rich Gulf of Mexico moisture will surge from the central Gulf Coast to the Central Plains.
By Christmas morning, the closed upper low in the Central Plains will foster a favorable environment for surface low pressure to quickly strengthen over Iowa.
On the western flank of the storm, heavy snow will increase in coverage and intensity throughout Christmas day across northern Kansas, Nebraska, and South Dakota.
Snowfall totals of >4" are expected, with a high chance (70+%) of a foot of snow from central Nebraska into south-central South Dakota.
In addition, very strong winds with gusts upwards of 55 mph will lead to Blizzard conditions.
While a White Christmas may be exciting for those nestled at home, the heavy snowfall rates and reduced visibilities due to blowing snow will make for hazardous to even impossible travel conditions.
From the Red River Valley of the North to northern Minnesota, significant icing is expected.
WPC probabilities show a high chance (70+%) of ice accumulations greater than 0.1" across the region, with moderate chances (40-60%) for more significant ice accumulations >0.25" in southeast North Dakota.
Treacherous travel conditions, slippery sidewalks, and isolated power outages due to ice are expected.
By Tuesday, the winter storm will gradually weaken but still produce a combination of heavy snow and blowing snow, shifting more westward into the central High Plains.
The Red River Valley of the North and northern Minnesota will contend with an icy wintry mix throughout the day.
Further east, Gulf of Mexico moisture funneling northward ahead of a passing cold front will spawn numerous showers and a few thunderstorms with moderate to locally heavy rainfall from the Great Lakes to the Ohio Valley and the Southeast.
Very heavy rainfall of several inches is forecast along portions of the Southern Appalachians, where a Slight Risk of Excessive Rainfall (level 2/4) has been issued as some scattered to potentially numerous instances of flash flooding will be possible.
By Tuesday, the plume of Gulf of Mexico moisture will work its way into the Mid-Atlantic as a secondary system organizes along the Southeast coast, continuing the chance for moderate to locally heavy rainfall, particularly along the southern and central Appalachians.
In the West, a new potent Pacific storm system will deliver rounds of heavy coastal/valley rain and snow to the Cascades Monday night and into Tuesday morning.
A wintry mix is forecast for the Columbia River Valley and Basin and may lead to hazardous travel conditions.
Some lighter snow will also spread into the northern Rockies.
Another system will follow quickly on the heels of the first, with precipitation beginning to pick back up again along the coast by Wednesday morning.
Temperature-wise, it's no surprise given all the rain that it will not be feeling a lot like Christmas from the Upper Midwest on east to the Great Lakes and East Coast.
On the heels of a Christmas Eve that sported numerous record warm min and max temps in the Upper Midwest, more unusually mild temps are expected Christmas Day in the Upper Midwest and Great Lakes where highs in the 50s are running between 15-25 degrees above normal.
The East Coast will not witness quite the anomalous warmth that the Midwest and Great Lakes will, but daily average temps into the 40s for New England and 50s and 60s further south will still be rather mild and could range between 10-15 degrees above normal.
Tuesday continues to be exceptionally mild in the Great Lakes and along the East Coast with more record breaking warm min temperatures scattered throughout the Great Lakes.
In contrast, the central/southern Plains and central/southern Rockies will be the coolest versus normal thanks to a recent cold frontal passage injecting the region with an air-mass that feels a lot more like Christmas, with 30s and 40s to the north and 50s to the south.
Conditions will be around average for the West, with 30s and 40s for the Great Basin, 50s and 60s along the coast, and 60s and 70s into the Desert Southwest. ■