With millions of people preparing to travel for the Thanksgiving holiday, two strong storm systems, including the first major winter storm of the season, are forecast to bring snow, wind and rain across a large swath of the United States this week.
According to the National Weather Service's Weather Prediction Center, the first system, which is expected to bring thunderstorms and possible tornadoes to the central and southern Plains, will collide with arctic air as it moves north, causing widespread snow to develop across the Dakotas, Minnesota and Wisconsin on Wednesday.
Up to a foot of snow is possible in parts of North Dakota. Winds combined with falling snow or snow on the ground will also reduce visibility and result in hazardous travel conditions.
Separately, an upper-level low pressure system was forecast to develop above the Great Lakes later this week, resulting in cooler temperatures, cold rain from the Ohio Valley to the East Coast and accumulating snow for the central Appalachians and parts of the Northeast and Midwest starting late Wednesday into Thursday.
Up to six inches of snow is possible on Thursday and Friday, especially in the higher elevations.
Meanwhile in the Pacific Northwest, an "atmospheric river event" was expected to bring heavy rain and snow to Oregon and Northern California for several days. The rainfall intensity is expected to peak on Thursday with dangerous flash flooding, rock slides and debris flow to follow.
"Rainfall accumulations over 10 inches are likely for portions of northern
California into far southwestern Oregon through Friday morning which will
lead to flooding rainfall and areas of flash flooding," the NWS said. "Accumulation rates of 2-3 inches an hour and wind gusts up to 65 mph will result in whiteout/blizzard conditions and near impossible travel."