An unseasonably deep low pressure center moved across the upper Midwest Thursday, spawning thunderstorms across the region. The storms erupted in somewhat humid air ahead of a cold front, where temperatures warmed to the low and mid 80s. Behind the front, winds gusting over 35 mph swept autumn-like air in from the northwest. Late afternoon temperatures were held in the 50s and low 60s across much of Minnesota and northern Iowa. This air will flow across the Chicago area Friday. Temperatures are forecast to stay below 70 degrees for the first time since May 25th. The influx of cool air is being driven by a buckle in the jet stream produced by winds flowing around the periphery of searing heat along the West coast. Readings will moderate well into the 70s over the weekend.