The cold front that passed across the area on Saturday ushered cooler, more seasonable air into the Midwest. Sunday’s highs are forecast to run 7 to 10 degrees lower than the 73-degree reading observed on Saturday. Temperatures through Tuesday are expected to rebound, averaging above normal despite Sunday’s initial cool down. More significant changes are expected to begin midweek. Computer models have been persistent in developing a large upper level low, which is forecast to be centered just north of lake Superior on Friday. This will dramatically alter jet stream flow. High-level wind flow has been mainly from the southwest since climatological autumn began on September 1st. The evolution of this large buckle in the jet stream will steer air into the region from the Canadian arctic, lowering area temps to mid-November levels.