After an excessively rainy May and June, the Chicago area has turned bone dry in July’s opening two weeks. Through Friday evening, the city’s official rainfall totaled just 0.27 inches, more than an inch below normal. Things should begin to change this weekend as a cold front interacts with the hot and increasingly humid air mass over the area, triggering several rounds of showers and thunderstorms, capable of producing downpours and strong winds. A line of severe storms erupted Friday evening from southern Wisconsin into eastern Iowa. Flooding rains topped five inches at Cassville, Wisconsin, while highs winds toppled trees and downed power lines in many locations. Peak wind gusts were 75 mph at Davenport, Iowa, 70 mph at South Wayne, Wisconsin and 65 mph at Dubuque, Iowa and Nora, Illinois. Cooler and less humid air should arrive by Tuesday and linger most of next week.