CHICAGO (AP) -- Severe thunderstorms, tornadoes and fierce winds sliced through the Midwest, leaving behind bitterly cold air and blizzards in the northern Plains that sent temperatures in some areas plummeting by 50 degrees in a few hours.

Forecasters warned more bad weather was on the way Wednesday.

"This is going to be a hard, vicious slap in the face from Mother Nature," Gino Izzi, a meteorologist with the National Weather Service in Romeoville, Ill., said Tuesday night. "The temperature drop we saw was really spectacular in a bad way."

High winds associated with thunderstorms may have killed two people in Indiana, authorities said Tuesday. Snow forced the closure of schools and highways in many areas, and avalanche warnings were issued for some Western regions.

"I wouldn't call it a common occurrence to see winds this strong with this kind of snow," Izzi said. "This isn't something we see every year."

The cold air and wind gusts as high as 70 mph slammed into the Midwest, where fog created problems for air travel Tuesday in Chicago. About 350 flights were canceled Tuesday at O'Hare International Airport, said Chicago Department of Aviation spokesman Karen Pride.

The system also dragged frigid air across the northern Plains. The Weather Service reported a midday temperature of minus-24 degrees at Glasgow, Mont. North Dakota registered wind chill factors of minus-54 degrees at Garrison, while Williston hit a low of minus-24 degrees.

Most of Minnesota was under wind chill warnings until noon Wednesday due to indexes that fell into the minus-30 degree level. It was as low as 50 degrees below freezing in Hibbing.

Though only light snow fell in western, central and eastern Iowa on Tuesday, winds snapping as fast as 60 mph caused visibility problems, and temperatures dropped into single digits.

In north central and eastern Iowa, forecasters expected strong winds and blowing snow to continue overnight, and for temperatures to possibly dip to 10 below zero.

"It's a little worse than your average snowstorm," said Rod Donovan, a meteorologist with the National Weather Service in Des Moines, Iowa. "The biggest impact is that the driving conditions can change quickly with this type of storm. Once it begins, travel is quite hazardous."

Some 1,500 workers went home early from the Mayo Clinic in Rochester, Minn., while critical medical staff were put up in hotels so they could stay close to serve patients. The blustery winds also put flight operations on ice at the Rochester airport.

Firefighters in southwestern Indiana pulled two bodies from a mobile home near Evansville that had been turned on its side by winds in a thunderstorm, WEHT-TV reported.

Residents near Danville, west of Indianapolis, reported funnel clouds, and damage was reported to a home and the Morgan County Courthouse in Martinsville.

The National Weather Service reported an unconfirmed tornado touchdown near Okawville, Ill. A corner of the roof peeled off a high school in Nashville, Ill., but no injuries were reported.

Temperatures in Illinois dropped from Tuesday's highs in the 40s to about zero overnight. In anticipation, some central Illinois schools canceled Wednesday classes.

In Cape Girardeau County, Mo., winds as strong as 70 mph and dime-size hail were reported Tuesday. Two unconfirmed funnel clouds were reported, said Dick Knaup, the county's emergency management director.

The week began with heavy snow pummeling mountain areas from Washington state to northern Arizona as two storms converged, one from hard-hit California and another from the Gulf of Alaska, meteorologists said.

The storms were followed Tuesday by a third that threatened to leave up to 20 inches of snow in Idaho's mountains, said Jay Breidenbach of the Weather Service office in Boise, Idaho.

A fourth storm was on the way to the interior West: "By Thursday, the next storm will be right on our doorstep. This is quite a storm system," Breidenbach said.

The Navajo reservation, which sprawls across parts of Arizona, Utah and New Mexico, was under an emergency declaration because of the possibility that melting snow could create flooding.

In the snow farther west, avalanche danger forced officials to close Interstate 90 at Snoqualmie Pass, Washington state's main east-west artery across the Cascade Mountains. The pass was to remain closed until Wednesday morning, Meagan McFadden of the state Department of Transportation said.

More than 200 trucks were backed up at North Bend, waiting to move freight across the pass. On a typical weekday, as many as 7,000 trucks travel I-90 over Snoqualmie Pass, she added.

Snow also closed highways in Minnesota, Colorado and Wyoming.

Two of three snowmobilers lost in the mountains west of Denver were found late Tuesday, said Summit County sheriff's spokeswoman Paulette Horr. The third was still missing.

In Oregon, two snowmobilers were rescued Monday after spending two nights in the Wallowa Mountains, where they were trapped by storms. Authorities said the two were dressed warmly and equipped with survival gear, matches and an avalanche beacon.

The threat of flooding as heavy snow melted brought an emergency declaration on the Navajo reservation sprawling across parts of Arizona, Utah and New Mexico.

Associated Press writers P. Solomon Banda in Denver; Sophia Tareen and Michael Tarm in Chicago; Henry C. Jackson in Des Moines, Iowa; Keith Ridler in Boise, Idaho; and Arthur H. Rotstein in Tucson, Ariz., contributed to this report.

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