A much more dynamic and volatile weather pattern is looming for the United States as the atmosphere begins to shift gears following a quieter start to December. By early next week, numerous small, weak disturbances will be replaced by one massive storm that could wreak havoc on cross-country travel as well as pose a significant threat to lives and property, AccuWeather meteorologists warn.
"The stage is being set for extreme weather conditions over the U.S. next week, especially for the middle of the nation," AccuWeather Chief On-Air Meteorologist Bernie Rayno said.
This week's weather will feature impacts from a series of weak storms that will deliver drenching rain from the south-central region to the Atlantic coast and stripes of snow from the Rockies to the Upper Midwest and interior Northeast.
One of the foundational pieces of next week's storm was located thousands of miles west of North America on Wednesday. A large storm loaded with moisture over the northern Pacific was forecast to drop toward the western United States this weekend.
From this weekend to next week, the jet stream will change from its current nearly west-to-east configuration to a very convoluted setup that favors at least one major storm.
The first phase of that storm will unfold this weekend, as it brings a substantial amount of rain to coastal areas and lower elevations and mountain snow to the Pacific coast. As the storm then moves across the Rockies, it will remain potent before it eventually reorganizes into a monstrous system by early next week over the Great Plains and Mississippi Valley.
As warm and moist air begins to flow northward from the Gulf of Mexico, shifting and strengthening winds above the ground to the jet stream level of the atmosphere will spark powerful thunderstorms over portions of the South Central states during the first part of next week.
"Not only is there likely to be an outbreak of severe thunderstorms with this [weather pattern], but multiple tornadoes are possible," Rayno said. "The setup could bring a greater number of tornadoes, compared to last week's outbreak in the Southern states as it seems there will be just too much energy available in the atmosphere for that not to occur."
There is a significant chance of tornadoes to be on the ground from Tuesday afternoon to Tuesday night over portions of the interstate 20, 30, 40 and 55 corridors, Rayno added.
Severe thunderstorms could occur west of the I-55 corridor late Monday and may extend well to the east from the Great Lakes to the Tennessee Valley on Wednesday.
Outside of severe thunderstorms, the surging moisture can produce locally heavy rain in parts of the same area. While the downpours are likely to bring yet another boost to river levels on the Mississippi and Ohio rivers, too much rain may fall too fast for small streams and artificial drainage systems to handle, which could result in some flooding around urban areas.
The dynamic storm will have a cold and wintry side as well.
Frigid air that has been hovering over south-central Canada for days will be pulled southward by the strengthening storm.
As this cold air is injected into the storm, a zone of high winds and heavy snow will unfold from portions of the central Rockies to the northern Plains from the early to the middle part of next week.
An all-out blizzard will likely unfold in at least part of the zone from Colorado to the Dakotas and northern Minnesota from Tuesday to Wednesday, Rayno said.
"Portions of the North Central states could be dealing with a doozy of a storm," AccuWeather Long-Range Meteorologist Brandon Buckingham said. "Moisture that is transported from the Gulf of Mexico all the way to the northern Plains by next Tuesday should be impressive."
The cold component of the storm will result in windswept, powdery snow with accumulation totals ranging from inches to a foot or more. Extensive blowing and drifting and difficult-to-impossible travel conditions in portions of the interstate 29, 90 and 94 corridors could occur.
But even as the storm pivots inland from the Pacific Ocean later this weekend to early next week, areas of heavy snow will break out in portions of Nevada, Arizona, Utah, New Mexico, Idaho, Colorado and Wyoming. Travel via interstates 15, 25, 40, 70 and 80 could be adversely affected.
Strong winds from the storm will also develop in portions of the Southwest and the southern High Plains. These winds could kick up dust, raise the wildfire danger and lead to vehicle rollovers on area highways.
AccuWeather forecasters say where the worst conditions in terms of snow and severe weather, including tornadoes, will occur will be determined by how quickly the storm strengthens and the track it eventually takes. AccuWeather's team of meteorologists will continue to examine the latest weather data available and refine forecasts as needed in the coming days.
Another risk forecasters will be exploring in association with the upcoming massive central U.S. storm will be the possibility of a spin-off or secondary storm later next week along the Atlantic coast. This potential storm could also produce its own zone of gusty winds, heavy rain and inland pockets of ice and snow.
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