Chicago weather: Two-day severe weather threat could bring tornadoes, strong winds

CHICAGO - An outbreak of severe weather is looking likely across our region over the next two days; make sure you are prepared and ready.

We saw a big uptick in the heat and humidity today, with heat index values in the 90s and even a couple of spots spilling into the triple digits. Along with that, we have seen spotty to isolated pockets of rain and thunder. Most of that activity will slowly taper off overnight tonight, but a leftover pocket of rain may linger through early morning.

Wednesday is shaping up to be a very hot and humid day with highs in the lower 90s and heat index values around 100 degrees for many. We will likely see a fair amount of sunshine as well. In addition, there is a growing threat for severe weather. 

Wednesday forecast:

Here's the breakdown for Wednesday: 

• What: Multiple rounds of strong to severe thunderstorms.
• When: 4 p.m. to 7 p.m. and 9 p.m. to 2 a.m.
• Concerns: Damaging straight-line wind gusts topping 70 mph, along with a few storms producing quarter-sized hail. A couple of tornadoes cannot be ruled out.

Plan on a watch and several warnings to be issued by the afternoon and evening. Make sure you have a way to get the alerts when they are issued and be prepared for alter plans around the storms.

Thursday's forecast:

Thursday is going to be somewhat similar with high heat and humidity along with another (higher) threat for severe weather. 

Depending on the timing of a cold front Thursday afternoon, things could get ugly in a hurry. This is how Thursday is shaping up:

• What: Large line of severe thunderstorms
• When: 4 p.m. to 10 p.m.
• Concerns: Damaging wind gusts topping 60 mph, multiple tornadoes, and hail larger than golf balls. We may be setting up for what is called a "QLCS" line of storms, and those tend to feature quick spin-ups and prompt numerous tornado warnings, so be prepared.

Looking ahead:

Once the storms move out, the dew points (humidity) will start to drop off and give us a little bit of relief. Highs will still be in the 80s for Friday, but with lower dew points, it won't feel as hot.

Another day of the 80s is expected on Saturday, followed by another weak cold front. That front may trigger some late evening rain and thunder. 

However, behind that front, our highs will fall into the 70s for Sunday through Tuesday of next. Expect a sunny to partly cloudy sky each day and morning lows in the upper 50s to lower 60s. There may be another chance for rain late Tuesday of next week.