Hopefully you were able to get out and enjoy the warmth this week because a shot of winter is here for the next 72 hours. We hit 73° on Thursday, which tied the record high for the day. That was the top of the roller coaster hill. Now, we are riding downhill! Friday afternoon we rose to 68° ahead of a potent cold front. As of Friday evening, we are sitting in the upper 30's across northern Illinois. That is roughly a 30-degree drop in temperatures in just about 7 hours of time. We can thank the cold front and very strong westerly winds for ushering in that sharp temperature change. Temperatures will continue to drop into the weekend with highs each afternoon in the upper 30's and lows both Saturday and Sunday night near 20°. It would be very possible to see low temperatures drop into the teens in outlying areas each night, especially in typically cold locations such as Freeport and Rochelle.
This is the first truly potent autumn storm system to affect the Midwest and Great Lakes regions. These types of systems are not abnormal. During the fall season, the warmth of the summer attempts to hang on. Meanwhile, the cold of winter tries moving in from Canada. As a result of the battling seasons, very intense low pressure systems develop and swing through the Midwest. And, typically, these systems take above average temperatures and send them back to reality, if not colder than where they should be.