UPDATED 02/01/11 4:19 p.m.

CHICAGO (CBS) — City officials are urging Chicagoans to stay indoors if the trip isn’t “absolutely necessary,” as a blizzard that could reach historic proportions rolls in.

“We want to make it clear that our first priority is always public safety,” Mayor Richard M. Daley said Tuesday afternoon. He urged Chicagoans to “exercise common sense during the storm” by staying indoors unless absolutely necessary and driving carefully when on the road.

The snow started early Tuesday afternoon and is expected to last until Office of Emergency Management and Communications executive director Jose Santiago said that between 9 p.m. Tuesday and 5 a.m. Wednesday, the rate will increase to 3 to 4 inches per hour, as winds pick up to 50 to 60 mph at the lakefront.

In the city of Chicago, most of the Cook County suburbs and Northwest Indiana, snow totals will likely top out in excess of 18 inches, CBS 2 Meteorologist Megan Glaros reported.

Santiago warned that the snowfall could even top out at 2 feet.

“There isn’t a reason to believe, at this point, that the storm will miss the city,” Santiago said Tuesday morning. “Every Chicago resident should brace for a storm that will be remembered for a long time.”

Chicago Public Schools have canceled classes on Wednesday as a result of the storm.

CPS Chief Executive Officer Terry Mazany said that, “based on the anticipation of very severe and dangerous weather conditions that could be harmful to students and their commute and their routine school day, we cannot compromise and risk their safety. Therefore we’ve decided to cancel school for tomorrow.”

Meantime, as of 3 p.m., Santiago said that 38 Chicago residents had called the city’s 311 non-emergency line to report not having any heat and 18 others had called requesting temporary shelter.

Santiago urged all Chicagoans to keep an eye on friends and neighbors, especially the elderly. If you can’t check on your neighbors yourself, officials ask that you call 311, Santiago said.

“This storm will test the city’s resources, and test the patience of Chicago residents used to dealing with inclement weather,” Santiago said. “We ask that everyone be patient, dress appropriately, and above all, if the trip isn’t absolutely necessary, stay indoors.”

The city has deployed a total of 274 city snow-fighting trucks and 100 garbage trucks equipped with “quick hitch” plows to clear the city’s main arterial streets and Lake Shore Drive, Department of Streets and Sanitation Commissioner Thomas Byrne said.

“Even with all of these trucks, snow that falls at the predicted rate will quickly cover the pavement and slow traffic,” Byrne said. “So our trucks will be out there doing the best job they can, but realize that in these types of conditions, traffic is slow and visibility will be limited, especially during rush hour. Motorists need to drive with extreme caution.”

When motorists arrive home, they are reminded not to park on arterial streets with “snow route” designations that forbid parking when snow is over 2 inches deep. Cars will be towed and relocated if necessary, Byrne said.

Meantime, the Chicago Fire Department has received 50 new snowmobiles to assist with responding to emergencies during the blizzard.

Fire Commissioner Robert Hoff said the snowmobiles can be used in emergencies when side streets are blocked by too much snow or stalled vehicles, so that firefighters and paramedics can still reach their destination quickly.

“Our most important thing is public safety and the people that are sick, we want to get them out of their homes and into hospitals,” Hoff said.

Daley said the city decided to use snowmobiles at the Fire Department after watching the problems that New York City faced after a major snowstorm earlier this winter, when many side streets and sidewalks became impassable.

On Wednesday morning, crews from the city’s Water Department and Transportation Department will work with Streets and Sanitation crews to clear out critical areas, including main intersections and fire hydrants, according to Byrne.

Byrne urged residents to help with snow removal by shoveling their sidewalks and piling the snow in parkways.

“Snow should never be pushed into the street,” Byrne said.

The departments of Water Management and Transportation will help dig out critical areas after the blizzard, Byrne said.

Streets and Sanitation has also increased the number of garbage trucks to get ahead of the weekly collection, Byrne said.

During the Blizzard of 1999, which dumped 21.6 inches of snow on the city, Lake Shore Drive had to be shut down for the first time in history.

Byrne said that would happen again if need be, and “we’re prepared as best that we can for anything that could happen along Lake Shore Drive.”

The Chicago Transit Authority is also monitoring forecasts, according to CTA President Richard Rodriguez. CTA buses and trains will run on a normal schedule, but trains will be longer to accommodate an increased volume of passengers, he said.

Trains will be equipped with snow plows, and on the Orange, Pink, Brown, Purple and Yellow lines, which do not run 24 hours, additional sleet trains will run to keep the tracks clear and thawed, Rodriguez said. Diesel-powered snow-fighting locomotives will also clear the tracks if necessary, he said.

At O’Hare International Airport, airlines have canceled more than 1,100 flights as of 10:30 a.m. Airlines were also reporting delays of 45 minutes or more for flights in and out of O’Hare.

At Midway International Airport, airlines have canceled more than 100 flights as of 10:30 a.m. Otherwise, no delays have been reported at Midway.

The Chicago Department of Aviation is working with the Federal Aviation Administration and the airports to clear snow from the runways throughout the duration of the storm, Chicago Aviation Commissioner Rosemarie Andolino said.

In short, the city is gearing up for a major, major storm, the likes of which has not been seen in at least 12 years.

CBS 2 Chief Correspondent Jay Levine reports someone suggested that during the blizzard each of the mayoral candidates should take 24 hours running the city, so that voters can judge them all and see how they really deal with a crisis. Gery Chico has already accepted the proposition.

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