Fast-moving undulations in the jet stream flow aloft will mark significant changes in Chicago’s weather pattern during the week ahead.
A northwest upper level flow will bring chilling Canadian air into the western Great Lakes today and Monday. A west to southwest flow steers low pressure over or just to the north allowing warm, moist air to briefly invade the area midweek. Northwest flow aloft returns Thursday followed by shift to the SW later Friday and Saturday.
Subtle variations in this high-level pattern can significantly impact the forecast for northeast Illinois. Computer models and forecasters are divided on the actual low pressure storm track which will be crucial to the Chicago projections. Should the low track follow a path through central Illinois, temperatures could be some 10 to 20° cooler than present forecasts. Either path will result in significant rainfall Wednesday.
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
