Severe weather threats across the United States have millions of Americans on alert for blizzard conditions, potential tornadoes and record-breaking high temperatures in the coming days.
More than 11.5 million people are under blizzard warnings, another 4.3 million are under winter storm warnings, and about 20.6 million are under an extreme heat watch, according to forecasters.
A storm sweeping system is expected to bring life-threatening travel conditions in the Northern Plains and Upper Great Lakes, the potential for damaging winds and tornadoes across the eastern half of the country on Monday.
Across parts of the West, an unusually early heat wave is expected for much of the week.
Blizzard slams Northern Plains, Upper Great Lakes
A rapidly intensifying storm is producing blizzard conditions from eastern South Dakota through Wisconsin into Michigan’s Upper Peninsula on Sunday.
More than a foot of snow fell in some portions of Minnesota and Wisconsin on Sunday, according to National Weather Service reports, with another several inches likely to fall in the Minneapolis area amid blizzard warnings by the weather service.
Warnings of hazardous road conditions were issued across Minnesota, Michigan and Wisconsin, where transportation officials warned of worsening conditions Sunday with low visibility and snow-covered roadways.
More than 600 flights flying out of and into the Minneapolis-Saint Paul International Airport were canceled Sunday, according to FlightAware, a website that tracks flight disruptions. Dozens more through Detroit were also scrapped.
State officials have issued a no-travel advisory in southern Minnesota, and Gov. Tim Walz has authorized the Minnesota National Guard to support emergency operations, CBS Minnesota reported.
Wisconsin snowplow driver Aaron Haas said it was one of the worst storms he had seen in years. On Sunday, he was stacking piles of snow as high as his truck in the town of Marshfield.
“You can’t see anything when you’re on the highways outside of the city,” he said.
Blizzard conditions are likely to stretch into Monday with additional lake-effect snow behind the storm.
Severe weather threat expanding east
The same storm fueling the blizzard is also triggering severe storms across the Midwest and South along a powerful cold front.
A developing squall line is expected to sweep across parts of the Midwest and Mid-South on Sunday, moving east overnight. Forecasters warn of an enhanced risk of severe weather from the Lower Great Lakes through the Ohio and Tennessee valleys.
CBS News 
The threat is expected to intensify Monday, when a moderate risk of severe weather stretches across parts of the Mid-Atlantic. Storms could produce tornadoes, damaging wind gusts, hail and flash flooding as they push toward the East Coast, according to forecasters.
A stretch from parts of South Carolina to Maryland appeared most likely to experience particularly damaging winds Monday afternoon, the weather service said. That could include Raleigh, North Carolina; Richmond, Virginia and the nation’s capital. The weather service said an increased — albeit much lower — risk stretched north to a portion of New York and south to northern Florida.
CBS News 
Early-season heat building in the West
While the central and eastern U.S. brace for storms, the western U.S. is heading into an unusually early heat wave driven by a strengthening ridge of high pressure.
Beginning Monday and continuing through much of the week, record-high temperatures are possible across Southern California, the Desert Southwest and the Great Basin, forecasters said. Desert areas could see temperatures climbing into the 90s and 100s, while much of California and the interior West may experience highs in the 70s and 80s.
The warm, dry, and windy pattern is also expected to increase wildfire danger across parts of the West and High Plains.
Landslides, rescues, and collapsed homes on Maui
Acres of farmland and homes have been flooded in Hawaii. Roads have been closed, and shelters opened. PowerOutage.us, which tracks outages nationwide, reported over 50,000 electric customers in Hawaii without power as of early Sunday.
Flash flooding has been a major problem in recent days in places like Maui, Molokai and the Big Island, where rain had been falling from 1 to 2 inches an hour overnight, according to the Hawaii Emergency Management Agency.
Maui County via AP 
Maui County Mayor Richard Bissen said in a social media post late Saturday that some areas of Maui had received 20 inches of rain in the previous 24 hours.
“We’re seeing flooding, landslides, sinkholes, debris and downed power lines across the county,” he said. Expressing gratitude in the Hawaiian language, the mayor added “mahalo for continuing to look out for one another.”
