CNN
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A major winter storm slammed into the western United States over the weekend, blanketing mountain areas with heavy snow, and is now poised to sweep across the country, threatening dangerous blizzards, strong tornadoes and flooding this week.
“This winter storm is a true coast-to-coast, top-to-bottom impact that will be felt by every person in the country at some point this week,” CNN meteorologist Brandon Miller said.
The storm has already brought avalanche warnings to parts of the West, closing major highways as conditions turned icy.
More than 10 million people in more than a dozen states are under some level of winter weather warning as the powerful storm moves across the county, bringing with it a multi-day severe storm threat.
The storm will strengthen as it travels east, bringing snow to the Rockies tonight, where a foot of snow is expected before the system strengthens even more.
The upper Midwest and northern and central Plains will be hardest hit overnight Monday into Tuesday as heavy snow falls.
“Snow accumulations through Tuesday morning will generally range between 6 and 12 inches, centrally across the northern High Plains,” the weather forecast center said. “The heaviest snow is currently forecast for western South Dakota and northwestern Nebraska, where upwards of 18 to 24 inches are possible.”
Meanwhile, a widespread area from eastern Wyoming and Colorado to western South Dakota and Nebraska will also have wind gusts up to 60 mph. Heavy snowfall and strong winds will set the stage for a blizzard, resulting in whiteout conditions and impossible travel.
Blizzard conditions are when there are sustained winds of 35 mph or higher and visibility below a quarter mile for at least three consecutive hours.
Winter storm warnings extend from the Canadian border to the Mexican border, and blizzard warnings extend from west of Denver to the Dakotas.
“All preparations for this storm should be underway and completed sooner rather than later,” the National Weather Service office in Rapid City said.
Some areas in the blizzard warning areas could receive up to 20 inches of snow. Winds can be strong enough to knock down tree limbs and cause power outages, and the harsh conditions can be deadly for anyone outdoors.
“Brozen wind chills, as low as 20 below zero, can cause frostbite on exposed skin in as little as 30 minutes,” the weather service in Cheyenne, Wyoming, said.
Farther east, ice warnings cover eastern North Dakota, where nearly half an inch of ice could accumulate. If it does, power outages are certain and travel will be impossible.
Icing is also possible in southwestern Minnesota and western Iowa, where one-tenth of an inch of ice may form.
While the storm brings sunny conditions to the north, the southern part of the storm will have the potential to bring late-season tornadoes along with severe thunderstorms.
Storms will move across western Kansas as well as the Texas and Oklahoma plains Monday afternoon. There is a risk level of 2 out of 5 of severe weather for this area.
“Thunderstorms are expected to develop near or after dusk,” the Storm Prediction Center said. They also mention “a risk of gusty winds, hail and a few tornadoes overnight tonight and into early Tuesday.”
As the storm system strengthens and pushes east on Tuesday, the possibility of damaging winds, hail, flash flooding and even severe tornadoes will be a concern for parts of the Deep South, especially central Louisiana and east Texas.
“All severe regimes will be possible with damaging winds, hail and some more tornadoes in late fall,” the Shreveport Weather Service said.
Shreveport, Monroe and Alexandria in Louisiana are at a 3 out of 5 risk level for severe weather.
“A few strong tornadoes are possible, especially in isolated storms that may develop just ahead of the main convective band,” the Storm Prediction Center said.
By Wednesday, storms are not expected to be as intense, but could still be strong along the Gulf Coast. New Orleans, Mobile and Tallahassee are under severe weather risk level 2 out of 5 as the potential for tornadoes will still exist.
Very heavy rain will also be a problem, as several inches of rain could fall in a short amount of time within some of the heaviest showers.
There is a Level 2 out of 4 risk of excessive rainfall focused in the Mississippi River Valley, as rainfall amounts could exceed 4 inches, leading to isolated pockets of flash flooding.
The area is starved for rain as the Mississippi River saw some of it the lowest water levels on record this fall. Rain this week could actually help the gauge get closer Memphis rises above low water stage for the first time since mid-August. The slight rise in water levels is expected to be only temporary, but is a positive sign of progress.
The storm has already created icy and dangerous conditions on key roads, authorities said Saturday closure a long stretch of Interstate 80, from Colfax in Northern California to Stateline, Nevada, due to “snow and near-zero visibility,” said Caltrans, the state’s transportation agency Twitter.
In the Sierra Nevada, total snowpack is already above average, according to the National Weather Service in Reno.
“The snowpack is about 225 percent of normal, so it’s more than double what we would expect this time in December,” said Mark Deutschendorf, a forecaster at the National Weather Service’s Reno office.
The Tahoe Basin and Eastern Sierra see total snowfall that is usually recorded in January.
The storm covered some mountainous areas withered by drought California with heavy snow, including Soda Springs in the northern part of the state, which received 60 inches of snow in just 48 hours.
“It’s a lot like Christmas here,” Deutschendorf said. “It didn’t come with a lot of wind and it stuck to everything. It’s like a postcard.
While noting that the snow totals so far have been impressive, Deutschendorf said he is “cautiously optimistic” about these precipitations putting major drought breakthrough in the state.
“We had a similar series of storms last year. We had a good lead and then January through March were incredibly dry,” explained Deutschendorf.
In California over the weekend, 48 inches of snow fell at Twin Bridges in a 48-hour period, 46 inches fell at Tahoe-Donner, 45 inches at Donner Peak and 44 inches at Palsades Tahoe Ski Area.
“We are buried,” Palisades Tahoe Ski Resort wrote on its website Sunday, sharing photos of thick snow blanketing the ski resort in Olympic Valley, California.
“This is definitely a storm to remember. We now have 7.5 feet of snow since December 1st. Plus, in just 24 hours from Saturday morning to Sunday morning, we received more than 35 inches of snow – the 6th largest 24-hour snowfall total on record,” resort operators wrote.
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