Tuesday's sunshine and comfortable temperatures and humidities belie the severe weather threat predicted to come together after midnight and into the predawn hours Wednesday. That's when strong fast-moving thunderstorms are to sweep across the Chicago area from the west, possibly delivering downpours, hail and potentially strong winds. The vigorous, jet stream-borne disturbance expected to ignite these storms was behind an eruption of severe weather Monday afternoon across the northern Plains and was still in progress as night fell. Several storms generated cloud tops scanned by radar to have heights of 67,000 feet. The worst of these storms unleashed grapefruit to softball-size hail that broke windows in buildings and cars at Hulett, Wyo. Another bombarded St. Francis, S.D., with hailstones the size of baseballs. At least five reports of twisters were filed with the Storm Prediction Center across four states, from Montana to the Dakotas, a region covered by five severe weather watches-two for tornadoes and three for thunderstorms.
This summer's days have generated much larger temperature deficits than the nights
Chicago is in the midst of its coolest July open in 40 years. The month's average temperature through late Monday was 68.5-degrees---four degrees below the long-term (50-year) average at O'Hare International Airport. The month has produced fewer than half the 80-degree or higher temperatures during the same period a year ago. The cool readings have had a beneficial effect. It's estimated these lower temperatures may have reduced the need for air conditioning by more than half.
This summer's days have generated much larger temperature deficits than the nights
Chicago is in the midst of its coolest July open in 40 years. The month's average temperature through late Monday was 68.5-degrees---four degrees below the long-term (50-year) average at O'Hare International Airport. The month has produced fewer than half the 80-degree or higher temperatures during the same period a year ago. The cool readings have had a beneficial effect. It's estimated these lower temperatures may have reduced the need for air conditioning by more than half.
