A strong May cold front will send temperatures tumbling as it moves across the Midwest and Plains late Monday. Monday will be warm in Chicago, Des Moines, Kansas City and Omaha with highs in the 80s ahead of the front. Enjoy those 80s because highs drop into the 50s and 60s by Tuesday. The warmth peaks across the Northeast Tuesday before the cold front moves in and drops temperatures below average for the rest of the week. See how cool it will get in your city…