From 5 to 10 inches of snow is expected to fall across the Chicago metro area Tuesday with travel conditions – both land and air - deteriorating rapidly Tuesday forenoon – severely-impacted conditions continuing through the afternoon into the evening hours.
A band of light snow has developed well in advance of the main low pressure system and could spread into the Chicago area later today and this evening, but air is so dry here that much of this snowfall will evaporate before reaching the ground – the main system snow – 5 to 10 inches – is set to arrive during the Tuesday morning rush hours – intensifying later that morning into the afternoon with the Tuesday afternoon-evening commute fully impacted.
Low pressure extends from North Dakota south into the central plains will track east-southeast during the next 24 to 36 hours – passing through Illinois Tuesday and continuing on to the east coast Wednesday. The map below depicts the areas forecast to be under winter weather conditions from Blizzard Warnings in northeast Montana and northwest North Dakota (red) to Winter Storm Warnings (pink-shaded) and Advisories (purple) over portions of North and South Dakota, Minnesota, Wisconsin, Iowa and Illinois. Winter Storm Watches are up farther east through northern Indiana and the southern tip of Lower Michigan into northwest Ohio and then to the east coast.
The National Storm Prediction Center has issued man-computer model mix maps depicting the probability of 4 and 8 inches of snow from 6am Tuesday until 6am Wednesday. Much of northern Illinois and Indiana and all of the Chicago area falls in the red – well over a 70 percent probability of 4 inches and (last map) nearly 50 percent area of 8-inches.
Winter Storm Depiction Map
Probability of at least 4 inches of snow 6am Tueday - 6am Wednesday
Probability of at least 8-inches of snow 6am Tuesday - 6am Wednesday