A massive coast-to-coast winter storm is sweeping across the nation, bringing exceptionally heavy snow, blizzard conditions, freezing rain and high winds. Fifty million Americans are under winter storm watch, winter weather warnings or alerts. And some locations are on blizzard warning as they prepare for the storm’s increased severity.
The weather alerts span virtually the entire Lower 48 from California to Maine, where the system will do its final work late Thursday evening. Until then, 1 to 2 feet of widespread snow is expected to fall over a 2,000-mile area of the country, with the bullseye near Minneapolis. There, the local National Weather Service office warns that this system is “expected to catch up with the top 5 heaviest snowstorms.”
The office also warns of “snow blowing and drifting significantly with whiteout conditions in open areas” and adds that travel could become nearly impossible in some places, with drifts that could reach several feet high.
A freezing rain transition zone is expected to the south of the system’s snow belt. Ice accumulations, including glaze bedding, could exceed half an inch locally, weighing down power lines and causing power outages. Dangerous travel and vegetation damage from the Corn Belt through the Midwest and even the interior of the Northeast is also expected.
A bowling ball-like upper air disturbance of cold air at high altitude, low pressure and rotation was plunging southeast from British Columbia into the western United States on Tuesday. It will pass over the Great Basin of Nevada in western Utah early Wednesday. At the same time, it will absorb energy from a second higher air system.
Those high-elevation systems will support the development of dual-surface downs: a weaker one over Kansas and a stronger one over Utah. Both will progress eastward over time, their counterclockwise circulations swirling moisture northward and helping generate winter precipitation as cold air crashes southward in their wake.
The duo will drift eastward with time, though the latter will be more powerful. They will ride along a stalled warm front, which will stretch from the north-central plains all the way to New York City. North of there, cold air will be mixed with winter precipitation or all snow. In the south, mostly rain. Strong gusts of wind will also accompany the storms.
The impact will be so widespread that it could drive continuously from the western side of Canada to Mexico and remain in areas under winter storm warning all the while. The Cascades and Sierra Nevada will see 6 to 12 hours of snow through late Wednesday; it will come north first, then work south in time as the instigating moisture plume sweeps along the coast. Some rain is possible in the lowlands, but mostly at high altitudes.
The first round of snow through Wednesday night is expected to be limited to the mountains of Washington State, Oregon, and northern and central California. Snowfall levels will drop as low as 1,000 feet due to unusually cold air, meaning heavy snow (a foot or more) may fall in communities unaccustomed to Old Man Winter’s frequent visits. In the highest peaks, it is likely 2 to 3 feet.
Then a second robust system will bring mountain snow and a healthy dose of valley rain to central and southern California Thursday through Friday.
Before then, strong winds will cover most of the desert Southwest and California, where a litany of wind warnings are in effect. Gusts of 40 to 60 mph (highest in high wind warning areas) are likely.
The winds will pick up on Tuesday afternoon and last through the first half of Wednesday.
Meanwhile, a batch of snow is working southeast from the Columbia River Basin. It will cross Idaho and Utah early Wednesday before a more pronounced spiral of snow builds under the nascent low pressure center. Heavy snow in the mountains is likely to cover virtually all of Intermountain West before the system spills over to the lowlands.
Central US and Great Lakes
The worst point of the system will come when it crosses the plains. The worst impacts will occur north of Interstate 80 in Nebraska and Iowa and south of Interstate 94; I-90 will be impassable during the height of the storm, which arrives Wednesday through early Thursday.
15 to 25 inches of snow is likely in Minneapolis, along with strong winds west of the metro area that could lead to blizzard conditions. The weather will deteriorate rapidly Wednesday morning, with snow rates at times exceeding an inch per hour. The National Weather Service in the Twin Cities calls the upcoming episode “historic.”
“Historically speaking, this event could very well disrupt the first five snowfalls in the Twin Cities dating back to 1884,” the bureau wrote. “The biggest, most memorable event that seems to happen every year was the 1991 Halloween Blizzard with 28.4 inches of snow. Number two was a storm over Thanksgiving weekend in 1985 that totaled 21.1 inches.
A historic winter storm will begin later today and last through Thursday. In addition to heavy snow with impressive totals, gusty winds will cause significant travel impacts. Here is a thread with current predictions and updated charts (1/5) #mnwx #wiwx pic.twitter.com/Syn07Gc4Ak
— NWS Twin Cities (@NWSTwinCities) February 21, 2023
The storm will charge eastward, starting as light snow in Wisconsin and Michigan Tuesday night before rainfall becomes moderate to heavy during the evening through Thursday. There may be a lull before one last round of snow Thursday night.
For Chicago and Detroit, a brief period of freezing rain is likely on Wednesday before a transition to normal rain.
The storm will enter the Northeast during the second half of Wednesday. As the warm front, upon which precipitation is traveling, rises northward, any initial winter precipitation over Pennsylvania, New Jersey, the New York City tri-state area, or southern New England will turn to rain.
Boston, Hartford and Providence will likely see a burst of heavy, wet snow Wednesday night before it abruptly changes to sleet and then rain. However, there may be some freezing rain in the Blackstone and Connecticut River Valleys, as well as the Berkshires and foothills of northwestern Connecticut. It is there that the sub-zero surface air seeping in from the north can prolong the winter weather.
In central and northern New England and upstate New York all snow will fall. It could pile up 8 to 14 inches, or possibly more. Winter storm watches are in effect. Snow is expected to come out eastward by Friday morning.
On the southern edge of the storm system’s precipitation shield, freezing rain is likely. This is due to overshoot, or the process by which mild moisture-laden air rises above a shallow lip of cold, dense, ground-hugging air. This means that liquid precipitation falls from the warm air above and into a cold layer where it can freeze rapidly upon contact with the ground.
Ice will be a concern in a swath about 50 to 100 miles wide that stretches from the Corn Belt to the East Coast. Central and northern Iowa north of Interstate 80, southern Wisconsin, most of Michigan, parts of New York, western Massachusetts, and southern Vermont and New Hampshire should closely monitor the system. This includes cities like Cedar Rapids, Madison, Milwaukee, Grand Rapids, Detroit, Buffalo, Syracuse and Albany.