Strong to severe storms to breed in very warm unstable air mass

For the remainder of the week Chicago will be under the influence of a very warm humid atmospherically-unstable air mass. Complicating matters will be a west-east-oriented frontal boundary that will vacillate north-south over northern Illinois and northwest Indiana and a 110 mile-per-hour jet stream aloft over Wisconsin.

Impulses embedded in the jet stream combined with the frontal boundary will trigger periodic lines/clusters of thunderstorms moving through our area capable of producing damaging winds, large hail, torrential flood-producing downpours and even a few tornadoes.

Flooding on the Des Plaines and Fox Rivers will be increased or the time in flood extended should some of these heavier thunderstorm-producing downpours pass over their drainage basins. Close attention should be paid to forthcoming Watches, Warnings and forecasts in the coming days.