29.2° Temp. Drop in 10 Minutes

This picture was taken late this afternoon at the Harrison Crib – the Chicago water intake, which is 2.75 miles east of downtown.  At 4 pm at the crib – the temperature was 77.2°, the wind was west at 22.3 mph and the humidity was 27.6%.  Shortly after that a strong cold front came through.  There was a quick gust to 36.7 mph.  At 5 pm, the temperature had dropped to 46.0°, the wind was north at 21.1 mph and the humidity had jumped to 80.4%.  At 6 pm, the temp. was down to 39.7°, the wind was up to…