Tuesday, June 15, 2010

Isolated Tornadoes possible in central Illinois today...

This is a somewhat late notice, but I like the odds at a couple tornadoes in central parts of Illinois today, likely around the Interstate 72 corridor. My target triangle at the moment for a few reports would be from Bloomington to Springfield to Mattoon this afternoon.

A decaying MCS and associated shortwave is approaching from Missouri this afternoon. Associated with this wave will be deep layer shear on the order of 40 knots with the H5 jet streak. Thunderstorms currently over the target area are hindering destabilization at the moment, but in their wake clearing skies should allow for a quick recovery and moderate destabilization. Ahead of the wave, surface winds should increase slightly and turn out of the south and even southeast further north at about 10 knots. This, along with a strengthening LLJ should supply the low level shear needed for rotating thunderstorms, and the 40-50 knot streak at H5 should be more than enough for sustained updrafts and supercell storms.

Storms should begin to develop early in the afternoon in southwest Illinois from around Quincy to St. Louis. Organization may take some time, but storms should reach severe levels by the time they reach the Interstate 55 corridor from Springfield south, as they move northeast. An upscale growth into an MCS is eventually likely, thus this early period from Springfield to Interstate 57 approximately is where tornadoes would be most likely with any storm. Low level shear should be greatest along Interstate 72, so I'd likely try and hug this area.

I'm still on the fence as to whether I will chase this event or not, but at this point am leaning more towards a yes. I'll likely make a decision by noon, and head south towards Bloomington to adjust from there, likely south a little more.

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