All the meteorological ingredients for thundery downpours are in place Friday. Powerful wind gusts are a threat as well. Winds are converging along an incoming cold front, a set-up which encourages air to “pileup” —leaving it no place to go but up. This vigorous ascension of air creates cumulonimbus clouds or -thunderheads—the tallest clouds on earth. The ability of such formidable mounds of cloudiness to completely block incoming daylight is why skies darken so ominously as t-storms approach. Friday’s muggy, 70° dew point air is to fuel concentrated downpours which threaten to force 40-50 m.p.h. winds blowing just above the surface to crash to earth as powerful storm gusts. Local 1” rainfalls are a possibility.
Seasonably cool air takes up residence this weekend. Several fast-moving disturbances sweep across the area Saturday and Sunday nights, which is when any weekend showers will occur.
--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.
