After a mild opening weekend of May that brought temperatures averaging nearly 10 degrees above normal, our weather became more March-like on Monday. The city’s official high of 48 degrees at O’Hare International Airport represented a 26 degree drop from Sunday, which will likely be the last day for some time to produce a temperature surplus. Forecast models have been very consistent in developing what is referred to as an “Omega block” along western North America by the end of the week. This type of pattern keeps the West warm, while polar-source air flows across the Great lakes and Northeast. As the term suggests, this feature blocks a typical west-to-east progression of weather systems, leading to the pattern’s persistence. Temperatures across the metro area are forecast to average more than 12 degrees below normal during the period of May 5th through the 14th.
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