South winds and sunshine allowed temperatures to warm quickly on Monday. The highs of 81 at O’Hare airport, and 82 at Midway were 16 degrees above normal, and only 5 degrees off the record for the respective sites. Change is on the way, and Tuesday promises to be much cooler, and cloudier. Late Monday evening, a vigorous storm system had moved to northeast Oklahoma after blanketing portions of Wyoming and Colorado with over a foot of snow. The Plains storm was ingesting moisture-rich, 70-degree dew point air, resulting in severe thunderstorm development across eastern Kansas and Oklahoma. This storm center will move northeast Tuesday, reaching central Illinois by evening. Rain and thunderstorms are to overspread the Chicago area, with heavy rainfall possible.