Two disturbances are forecast to impact the region through the midweek period. Late Monday evening, satellite imagery showed a zone of shear, or turning aloft extending from southern Canada to Missouri. Clouds and light rain are expected as this area passes overhead on Tuesday. Temperatures remain cold enough aloft that some snow may be mixed in, mainly north of the city. Stronger low pressure is to evolve over the plains Wednesday, spreading precipitation across the Midwest and Great Lakes Wednesday night and Thursday. Though not a major storm, forecasts suggest much of Chicago could receive around a half inch of rain. This system will track well west and north of the metro area, ensuring that temps will rise above normal. Mild air has been absent for almost a month. Over the past 28 days, 27 have registered temperature deficits.