Heavy rain and thunderstorms were moving through Illinois Friday afternoon, with another round of severe weather likely to begin overnight. Flash flooding is also possible.
Meanwhile, winter storm watches and warnings have been issued for Idaho, Montana and Washington state.
A winter storm will be especially severe for parts of Western Montana, where some areas could see up to 50 inches of snow.
The National Weather Service says this snowstorm could be compared to the one in September 1934.
The storm could create whiteout conditions and very dangerous travel.
In addition to heavy snow, winds are expected to gust near 50 mph, which will create near-zero visibility and blizzard-like conditions.
Cold temperatures and wind chills are also expected Sunday in the Northern Rockies and the Pacific Northwest.
In the Tropical Atlantic, there are still two tropical cyclones: Lorenzo, a Category 4 hurricane with winds of 145 mph, and Karen, with winds of 40 mph.
Karen is expected to dissipate and not pose any threat to the U.S. or any landmass.
On Thursday, monsoon storms dropped as much as 2 to 3 inches of rain in a short period of time, creating flash flooding in parts of Southern California and Arizona.
Some roads even had to shut down due to the water rushing over them; however, the monsoon storms were mostly over as of Friday.