Photos: A Rare Tornado Circled Chicago's West Side Yesterday
By Stephen Gossett in News on Aug 10, 2016 2:26PM
Photo: Melanie Harnacke, MDW observer / Courtesy National Weather Service
A minor, "fair-weather" kind of tornado known as a landspout was spotted on Tuesday afternoon around the South Lawndale and Little Village neighborhoods. It was the first tornado within the city limits since 2006, when one briefly formed on the Loyola University campus, according to the National Weather Service.
A phenomenon formed "on the lake breeze boundary," according to the NWS, shortly before 4 p.m. It lasted only about 12 minutes before dissipating.
According to the National Weather Service, a landspout is “a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone (on radar)."
Ben Deubelbeiss, meteorologist at National Weather Service of Romeoville-Chicago, unpacked that definition for us laypeople, comparing the landspout to a spinning figure skater. "When they pull their arms in, they accelerate. This has the same effect," he told Chicagoist. Think of the landspout as the slower-spinning skater with arms stretched out.
The "typically very weak" landspout differs from the "classic, plains" tornado in that it is not supercellular, Deubelbeiss said. "Land and water spouts form from when preexisting spin is in the atmosphere. The vertical stretch from the cloud intensifies and produces the spout. It can form from any fair-weather cumulus cloud in the right conditions."