High Winds, 'Thundersnow' Expected as Rain Becomes Flurries

Don't let the rain fool you.

Drizzle is expected to turn to snow beginning around 3 p.m. today across the North Side of Chicago and throughout the city's metropolitan area. The National Weather Service has issued both a winter storm warning and hazardous weather outlook for the area; the first in effect until 3 a.m.

The most intense snowfall is expected between 5 and 9 p.m.

Conditions are thanks to a powerful system moving across the central United States, which continues to bring "significant, widespread impacts in the form of blizzard conditions, severe thunderstorms, damaging winds and fire …" 

The Chicago Department of Streets and Sanitation said it already has 285,000 tons of salt ready for Thursday's big storm, ABC Chicago reports. In addition, Huffington Post Chicago indicated around 2 p.m. that 142 flights had so far been canceled and another 131, delayed at O'Hare International Airport. Southwest Airlines out of Midway canceled all outgoing flights leaving after 4 p.m.

Meanwhile, a separate storm is beginning to impact the Pacific Northwest and northern California, where heavy mountain snow and coastal flash flooding is possible. Locally, Chicagoans can expect high winds and snow. The chance of precipitation is listed as 100 percent.

"Winds will become northwest and increase to 30 to 40 mph by late afternoon and evening with damaging wind gusts of 50 to 60 mph possible," the outlook says. "Downed tree limbs and power lines could cause power outages."

It also notes that snow will become heavy at times with snowfall rate of 1 to 2 inches per hour possible. There's also a chance of thundersnow, predicted by both the NWS and the Northern Illinois Storm Chaser Forecasting Facebook page.

"Intense thundersnow will boost rates and totals over the area," says a post on the group's page. "Chicago metro could get 3 inches south to 6 north all being blown around by 60 mph winds."

Meteorologists say the event will be short in duration.

The NWS reminds commuters that the combination of heavy wet snow and very strong winds will create "blizzard-like" conditions late into the afternoon and into the evening, particularly in the far west suburbs. 

To catch a glimpse of Thundersnow in Chicago, see the attached YouTube video, which features Weather Channel meteorologist Jim Cantore, who is jolted by the crash of the thunder during the February 2011 blizzard.

—by Carrie Frillman