There is a 70 percent chance or greater for at least 4 inches of snow across the Chicago area Tuesday according to a computer driven/forecaster mix derived by the National Weather Service. The two maps below portray the chances of a four-inch or greater and an 8-inch or greater snowfall from 6pm Monday until 6pm Tuesday.
With the intensifying center of low pressure tracking up the Ohio River Valley through Indiana into Ohio Tuesday, strong winds in our area will be out of the northeast off of Lake Michigan for an extended period of time. Thus Illinois lakefront locations and immediately inland will bear the impact of the combined storm snowfall as well as the enhanced lake-effect snowfall associated with this storm.
The first map below shows northern Illinois and the Chicago area in the highest probability (70 percent or greater – outlined in red). The second map displays the probability of 8-inches or more during this time period, and approximently the same area of Illinois is outlined in green indicating at least a 40 percent chance of 8-inches during the 24-hour period beginning 6am this evening.
Probability of 4-inches or more snowfall 6pm Monday - 6pm Tuesday
Probability of 8-inches or more snowfall 6pm Monday - 6pm Tuesday