Snowstorm plastering Rockies will hit Plains amid post-Thanksgiving travel

The snowstorm heralds a dramatic drop in temperatures that will spill across much of the Lower 48. By Thursday morning next week, the National Weather Service is expecting morning lows in the 20s in at least 45 states across the continental United States.

Winter storm warnings blanket much of Wyoming, Nebraska and Kansas, while winter weather advisories reach down to northwest Oklahoma and the Texas Panhandle. The snow is winding down in Denver, but the risk of snow is increasing closer to Kansas City.

Return-from-Thanksgiving travel is looking dicey across portions of the Intermountain West and Plains. The season’s first widespread, significant snowfall is plastering the Rockies and will sweep across the central states with plowable snow from the Canadian border to Kansas.

Where the snow is now?

Moisture being pinwheeled north around a low pressure center, which was anchored in western Utah and shifting east, sent scattered snow showers, some heavy, across Wyoming, southern Idaho, Colorado and Utah as of Friday morning. The activity, which was located beneath a pocket of high altitude cold air, low pressure and spin associated with a low pressure system, fostered more ascent, or lift, to enhance snowfall rates.

Moisture advection, or the influx of moisture from the south, sent a band of light to locally moderate snow to the Nebraska Sandhills and northwestern Kansas. Some of the moisture, contained in slightly milder, less dense air, was riding up and over a lip of cold, dense air near the ground. As the moist air cooled, it released its excess moisture in the form of snowflakes. Accumulations of 3 to 5 inches are likely within this zone.

How much has fallen thus far?

According to Weather Company meteorologist Jonathan Erdman, Lander, Wyo., picked up 18.8 inches of snow on Thanksgiving. That's nearly twice the November average. It was also the community's snowiest day in almost a quarter century, Erdman said.

Here are some of the biggest snow totals in the National Weather Service's database:

What’s next?

Low pressure will shift east on Friday, causing the swirl of show showers to move east with it. The high terrain of central and western Colorado will continue to see intermittent heavy snow, with totals in the mountains approaching a foot. In Denver, only another inch or so is expected; winds locally may come from the north in the Mile High City, inducing drying that could cut back on accumulations.

By early Saturday, the low pressure system crosses into northwest Kansas. Snow will taper off into early Saturday across the Nebraska panhandle and Sandhills. A cold front will trail southwest of the maturing low pressure system; along this front, a band of moderate snow is likely, and will persist for much of the day over central Kansas and south central Nebraska. Accumulations of 3 to 6 inches are likely in Kansas, with localized totals up to 8 inches around the intersection of Interstates 35 and 80.

Farther south into northwest Oklahoma and the Texas panhandle, mixed precipitation is anticipated. Places like Woodward, Okla., could see up to 3 inches of snow, along with icing.

Kansas City could see snow on Saturday evening, but it's too early to predict potential accumulations. The band of precipitation will begin to lose moisture and swing northeast toward Chicago and the Great Lakes on Sunday as a new system comes in behind it out of the Upper Midwest.

Behind the low pressure systems and cold front, Canadian high pressure will build. By the middle of next week, overnight lows in the 20s could reach as far south as North Texas and the mountains of North and South Carolina.