Rough weather could threaten portions of the Chicago area late Saturday, a development which may trigger severe weather. The new, more powerful late-day storms would follow the lingering showers and thunderstorms Saturday morning. Those rains are part of a disturbance that walloped south-central Missouri with nearly 5” of rain late Friday while producing thunderstorms downstate—one of which spawned a tornado around 3 p.m. in east-central Illinois near the Indiana border, 4 miles north of Casey, Ill. The twister there was photographed and appeared to occur at the front of the thunderstorm rather than beneath the southwest quadrant of the parent cumulonimbus (the cottony cloud which produces t-storms). This suggests the swirling winds may have been part of a less conventional, shallower circulation known as a “gustnado.”
A cold front, which slashed readings 30-plus degrees between Thursday afternoon and Friday evening, is northbound again. It’s to pass Chicago between 3-4 p.m. this afternoon, shifting cool ESE winds off the lake more southerly.
--By Tom Skilling, WGN-TV Chief Meteorologist
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
