Wednesday, June 14, 2017

Strong Storms Possible Wednesday

It has been a very muggy morning, it's not even noon and dew points are currently in the low 70's for many! This is a very tropical like air mass, something that is more typical of the late summer across our neck of the woods. High dew point numbers today are once again already bringing heat index values into the 90's. And we can expect heat index as high as 100° this afternoon, however any storms we get will drop temperatures this afternoon.

Along with the sticky feel, high dew points will also lead to heavy rain producing thunderstorms. Storms will be efficient rain producers because of the high amounts of moisture available, along with their slow moving nature.

Storms will develop midday as a couple features come into play. First features will be a few mid-level impulses that will be moving through northern Illinois today, ahead of our next cold front. As clouds are clearing, we are able to generate more and more instability in the atmosphere that will help to be 'fuel' for thunderstorms. This moist and unstable environment will be key to storm development.

Along with a few 'disturbances' or impulses(energy) moving into the area, we also have an old outflow boundary nearby. Like yesterday, this boundary will be a focal point for storms to develop today.

With high moisture, instability, and even some wind shear; strong to severe storms will be possible today. The storm prediction center shows the Stateline and much of the Midwest under a 'slight risk' for severe storms this afternoon. Biggest threats would be heavy rain, hail, and strong winds. The tornado threat is low, but not zero today.

The best timing is midday to late afternoon, as this time is when we are under peak heating from the sun, and are able to generate a lot of instability to fuel storms. We are just waiting for those energy waves which will be the 'spark' for storms. Storms should begin to fade this evening as we lose the energy.

A cold front passes early Thursday, which will bring back more sunshine. It won't feel any cooler behind the front, we will still be near 90°, but drier air advects in. This means it will be less humid and feel much more comfortable.

Make sure to check back for updates regarding storm potential today.

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