Less than two weeks ago, southern Minnesota had 25 cm of snow on the ground. Yesterday, the region hit 40°C following the biggest two-day temperature swing in decades:
Even more dramatic were the stunning weather changes which occurred to Chicago's west Tuesday. Soaring temperatures smashed records from Nebraska into western Iowa, Minnesota and western Wisconsin—areas which less than 2 weeks earlier had been crippled by a record-breaking foot or more of late-season snow.
Albert Lea, Minnesota recorded a 38°C high Tuesday. Only 12 days earlier that city had been buried under a 250 mm accumulation of snow.
Iowa's state climatologist Harry Hillaker reported in a special weather statement out of the National Weather Service Forecast Office in Des Moines Tuesday that 38°C or higher temperatures have occurred in the month of May on only 11 occasions since official weather records began in the state in 1873. Even rarer have been 38°C readings two weeks after a major snowstorm. Hillaker reports this has happened only a few times over that period.
Here in Chicago, O'Hare hit 33°C and Midway hit 32°C, while at Inner Drive Technology World Headquarters—800 m from Lake Michigan—the temperature hovered around 21°C until the sun went down. Without the sun heating the city, the lake breeze stopped, and temperatures rose. Sitting at Wrigley Field last night, I had my sweater on in the first two innings and was down to a T-shirt by the 6th.
Today's forecast calls for rapidly dropping temperatures bottoming out around 14°C by 4pm.
Welcome to 400 ppm CO2, folks. With more energy in the atmosphere, continental climates like the Midwest U.S. will have these violent temperature changes pretty normally from now on.