Wall clouds, like the one picture here near Rockford late Thursday, are low hanging cloud formations often near the southwest quadrant of powerful thunderstorms beneath which tornadoes often spring to life. These photos, taken just before sunset and relayed to us by Scott Lasker and Brad Bartley, accompanied a powerful northeastbound cluster of thunderstorm—one of several which flared in north-central Illinois Thursday and proceeded quickly into Wisconsin.
Far more numerous thunderstorms flared later Thursday evening knocking out power around 9 p.m. on the west side of Davenport Iowa, and shortly afterward prompting reports of funnel clouds near Rock Falls, Morrison and Tampico, Illinois in Whiteside County.
Explosions of power transformers were so numerous, a National Weather Service-trained spotter reported they appeared to "light up the sky" east of Dixon, Illinois. Trees and power lines were reported down in storm gusts which raked Sterling. Gusts reached 60 m.p.h. at Mt. Morris. The late night storm eruption prompted the issuance of a tornado watch which included a large swath of the Chicago area through 5 a.m. Friday morning.
Our thanks to Scott Lasker and Brad Bartley for sharing the amazing wall cloud photos with us!
-Tom Skilling
Photos courtesy: Scott Lasker and Brad Bartley
