KEARNEY, Neb. – Dangerous blizzard conditions from a developing low-pressure system are expected to snarl travel along major interstates in the central U.S. for the millions of last-minute holiday travelers hitting the road or catching a flight on Christmas Eve or Christmas Day.
A powerful storm that already caused problems for Southern California and the Desert Southwest last week, fueled by an El Niño-charged southern jet stream, is now teaming up with another storm dropping out of the Pacific Northwest to create a variety of impactful weather.
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While those on the warm side of the storm in the southern Plains and along the Gulf Coast will face a soaking rain and an isolated flash flood threat, the backside side of the storm will bring heavy snow as a cold air mass from Canada dips into northern portions of the U.S.
As of Sunday morning, areas of snow over the central Rockies were beginning to extend northeastward into the central Plains and parts of the northern Plains, where Blizzard Warnings are now in effect.
Up to a half-foot of snow had already been measured west of Denver in the Rockies of Colorado as of early Sunday. As much as 8 inches was recorded in Burlington, Colorado, along the state border with Kansas.
While only minor accumulations were reported around the Denver-Boulder area, it was likely a welcome sight with Santa on his way in a matter of hours.
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Blizzard Warnings have been issued for more than a half-million people across southeastern and south-central South Dakota and central and northeastern Nebraska.
Winter Storm Warnings, Winter Storm Watches and Winter Weather Advisories are in effect for other portions of the region, stretching from parts of Wyoming and Colorado northeastward to portions of western and northern Kansas, Nebraska, South Dakota and North Dakota.
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The complex interaction between the low-pressure system, an upper-level dip in the jet stream and the cold air mass is forecast to kick the entire storm system farther east toward the Mississippi Valley overnight on Christmas Eve, with a more rapid intensification of the low-pressure system expected to take place over the western portion of the Midwest on Christmas Day.
The low-pressure system will intensify even more rapidly from Christmas night into Tuesday morning, introducing a significant threat of strong, gusty winds that will increase and expand across the north-central U.S. With cold air being wrapped around this intensifying storm, the chance of a blizzard continues to increase across the northern and central Plains, with Monday night to Tuesday morning being the most likely time for dangerous blizzard conditions to occur.
According to the National Weather Service, a snowstorm must reach the following criteria to become an official blizzard: sustained winds or frequent gusts to at least 35 mph and considerable falling and/or blowing snow that frequently reduces visibility to one-quarter mile or less, both of which must persist for a period of three hours or longer.
Over a foot of snow is expected to overlap with wind gusts as high as 50-55 mph in the areas under Blizzard Warnings, some of which will remain in effect through 6 a.m. CST Wednesday.
“So this is going to be a major concern over portions of (Interstate) 80, I-29 and even close to I-90,” FOX Weather Meteorologist Craig Herrera said.
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In addition, a wintry mix of sleet and freezing rain will likely be an issue farther east and northeast from the northern Plains to Minnesota from Christmas Day through Tuesday night.
The best chances of any ice accretion appear to be concentrated along Interstate 29 in the eastern Dakotas and western Minnesota, where freezing rain is possible beginning Christmas morning. The freezing rain threat spreads farther west and north on Christmas night.
“The freezing line is a very fine line, so those of you over eastern Nebraska will be dealing with rain, switching to snow in the evening hours,” Herrera said.
By Tuesday, a band of freezing rain with potentially disruptive amounts of ice accretion could stretch from eastern Nebraska and western Iowa to the eastern Dakotas and western and northern Minnesota. This could disrupt travel in Fargo and Grand Forks in North Dakota, Sioux Falls in South Dakota and Sioux City in Iowa.
“We could have a glazing of ice … which can be very disruptive, too,” Herrera added. “Especially bridges and overpasses (along) major interstates like I-94, I-90, I-29 – these will be areas to watch if you’re heading home after the holidays.”
Here is a series of maps highlighting the timing of this massive storm as it tracks across the central U.S. over the next few days.
It is already underway in some areas and will continue to create travel impacts across portions of the Plains and Midwest through Wednesday morning.
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