Landspout tornadoes possible as thunderstorms and waves of rain bring flooding risk to Chicago area
Waves of rain and thunderstorms could lead to flooding it the Chicago area Monday evening and overnight, and bring with them the risk of unusual landspout tornadoes.
A stationary front wavering in place over the area is meeting an upper-level disturbance that is moving into the area, which will bring rounds of torrential downpours.
The chance for storms and downpours increases as the day goes on, with the heaviest rain in the city expected between 4 p.m. and 6:30 p.m. Rain will move in from the west and southwest, and could cause ponding on the roadways during the evening commute.
More spotty showers and storms remain in the forecast overnight and into Tuesday.
The conditions Monday are right for the possibility of landspout tornadoes, mainly south and west of the city, through sunset.
What is a landspout tornado?
Landspout tornadoes are brief, weaker tornadoes that form in a different way than typical tornadoes
Instead of developing from a rotating supercell thunderstorm, landspouts form when weak spin already near the ground gets stretched upward by a growing shower or thunderstorm. They're common in moist, tropical environments, like the one we have locally this week.
On Monday, a nearby mesoscale convective system – essentially a complex of thunderstorms that has formed its own low pressure system – is providing just enough low-level spin and rising air for a few funnel clouds or landspouts to develop.
Because landspouts are usually not tied to powerful supercells, they are generally less concerning than typical severe weather tornadoes. They tend to be short-lived, narrow, and relatively weak.
A brief landspout can still cause localized damage if it touches down, especially to trees, signs, and outdoor furniture.
Heat and severe storms later this week
While only spotty showers will linger tonight, as the week goes on the conditions will become riper for more dangerous severe weather.
Tuesday and Wednesday night more waves of rain are possible, and some storms could produce gusty winds. By Thursday, strong to severe storms are in the forecast with the biggest concerns at this point being heavy rain and small hail.
The week is also set to get hotter, with highs in the upper 80s Tuesday and back in the 90s Wednesday and Thursday with high humidity. Heat index values will range from the low- to mid-90s Wednesday and Thursday, and could drive stronger storms if they develop.
