Weekend heat brings more storms
Wednesday’s thunderstorms in Chicago brought the monthly rainfall total to 3.79", some 0.40" above normal and over five times the 0.72" total by the same time last June during last summer’s drought. The upper level trough stalled over the Midwest for the past four days is finally drifting eastward, bringing along the recent soggy weather and cool temperatures. In its place, the rain ends and temperatures climb.
By the weekend, the heat in the West finally crosses the Mississippi, causing temperatures to climb past 90° across the region. Gulf moisture is injected into the mix, so humidity also climbs to uncomfortable levels while overnight temperatures linger above 70°.
The increased humidity provides fuel in the fairly unstable upper atmosphere—enough that thunderstorms with significant rainfall are possible from Saturday through Monday.
-Dennis Haller, WGN-TV Meteorologist