A persistent upper-level jet stream pattern flowing from the Southwest to northern New England has allowed a series of low pressure systems to develop in the southern Rockies and Texas Panhandle and move northeast through the Ohio Valley to the East Coast. This pattern is expected to continue into midweek, with two more low pressure surges forecast to impact northern Illinois Tuesday and Thursday. Water-equivalent precipitation with the late Monday night/Tuesday storm could be as much as a half to one inch, so surface temperatures now forecast to warm slightly above freezing will be crucial as to whether northeast Illinois will receive rain or freezing rain.
The following storm looks like it will lean more to the cold side with a rain/wet snow combination beginning later Wednesday. The upper-air pattern will then shift northwest-southeast over Chicago, and a cold Canadian air mass will be steered into the western Great Lakes late in the week.
--By Paul Dailey, WGN Weather Center Meteorologist
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
