What to worry about next: The freeze

Now that you've cleared 20 inches of snow off your car, driveway and sidewalk, get ready for Mother Nature's next punch: subzero temperatures.

Temperatures in the suburbs were expected to plunge to between 10 and 20 below zero Wednesday night, and even though the winds will diminish, it was expected to feel like 20 to 40 below zero outside.

The forecast high temperature Thursday is between 9 and 13 degrees, and then Friday? More snow.

“It's a weak system,” said National Weather Service meteorologist Gino Izzo, “but it's more snow.”

The brutal weather week has potential to damage property, make outdoor activity more dangerous, and keep schools and businesses and roads closed.

As snowblowers buzzed Wednesday afternoon and children played in the snow drifts, suburban schools weighed whether to take a second, or in some cases, third snow day.

By early Wednesday evening, nearly every school in northeastern Illinois decided to remain closed Thursday.

In anticipation of the deep freeze, weary public works crews were rushing to finish plowing side streets and get some de-icing agents on the ground before the temperatures dipped below 10 degrees, which makes salt ineffective.

“What we don't clear today will be here for a while,” said West Dundee Village Manager Joe Cavallaro. “We want to effectively clear streets today and then throw salt and the beet juice mixture down.”

In Carpentersville, Village President Ed Ritter was going to have crews start salting the roads Wednesday night.

“If it gets really, really cold out there, there's not a whole lot that will melt the ice,” Ritter said. “We'll get salt down to get some grit on the road so drivers will at least get a bit of traction.”

A wind chill watch is set to go into effect at 9 p.m. The cold also could keep O'Hare and Midway airports from fully resuming their flight schedules, which is bad news given that the airports were essentially closed most of Tuesday and Wednesday. The cancellations would continue to be in effect until early Thursday morning, officials said. The airports remain open to help stranded passengers.

Metra, struggling to run on a reduced Sunday schedule on Wednesday, also was assessing plans for Thursday and referred riders to metrarail.com as conditions change.

Another problem the heavy snow followed by frigid temperatures can cause: ice dams on roofs. Sun and heat from the attic melt the snow on the roof and it can seep into the shingles and cause leaks, or pile up and rip off gutters or pieces of roof, according to the Rosemont-based National Roofing Contractors Association.

An alert from the National Weather Service Wednesday warned the snow and cold means “a silent danger may loom” for humans, too.

People can suffer hypothermia by sweating in the cold wind chills, or suffer a heart attack while overexerting themselves while pushing cars or shoveling huge amounts of snow. Exhausted drivers can cause accidents.

“Those unaccustomed to exercise are urged to use extreme caution,” the alert said.

In the 1999 blizzard, which was comparable to this one, Izzi said 43 people died of heart attacks while shoveling snow.

“We're really worried about people underestimating how much effort it takes to shovel,” Izzi said.

In the suburbs, at least two deaths have been attributed to the weather. A man was found dead in a car on Route 45 in Grayslake around 11 p.m. Tuesday, and an 84-year-old Lake County man suffered a heart attack while shoveling Wednesday.

Gov. Pat Quinn has declared the state a weather disaster area, and in Cook County, board President Toni Preckwinkle declared a state of emergency, ordering employees under the jurisdiction of her office to stay home except for those involved in essential services for public safety. She said county hospitals would remain open during the storm and she expects “regular county operations will resume” Thursday.

The Blizzard of 2011 fell just short of being the biggest snowstorm in Chicago history. The National Weather Service said 20.2 inches of snow had fallen at O'Hare, ranking it third behind the blizzards in 1967 (23 inches) and 1999 (21.6 inches).

“It missed by less than two inches,” Izzi said. “This is pretty much as big as it gets in Chicago.”

Ÿ Daily Herald staff writers Larissa Chinwah, Paul Biasco and Ted Cox contributed to this report.