High pressure will move east of the area Saturday morning, allowing southwest winds to develop. The shift in wind flow is expected to bring a modest increase in warmth and humidity to the region in advance of a southbound cold front over the upper Midwest. Meanwhile, a disturbance over central Canada is to move southeast, acting to push the front south of the Chicago area by early Sunday. As the boundary passes late Saturday night, scattered thunderstorms may develop. The Storm Prediction Center says there is a marginal risk of severe storms in the metro area. Any storms that do occur will be brief and localized, limiting heavy rainfall potential. With this activity due to arrive overnight, storms are expected to be in a weakening mode. Sunday is forecast to bring another influx of cool, dry, stable, storm-free air.