When to expect dangerous storms

1:15pm Conference Call Update:
We just wrapped up with a conference call with the Chicago National Weather Service and our thinking has not changed much from this morning.  The potential remains for strong to severe thunderstorms Thursday afternoon and evening, but the greatest limiting factor is going to be ongoing morning storms and cloud cover.  Even if we were to get a few hours of clearing, or some sunshine, during the early to mid afternoon, that could be enough to quickly allow storms to develop.  Greatest storm threats still appear to be damaging winds, hail and isolated tornadoes.

The weather could change quickly Thursday afternoon, so it's important to have your severe weather plan in place now.  Even if you don't need it tomorrow, you will need it again so now is the time to prepare!



Morning post:
A few stronger thunderstorms rolled through eastern Iowa and west-central Illinois earlier this morning producing up to golf ball sized hail.  We even had a few quick hitting and heavy rain producing storms move through Ogle and DeKalb counties.  Pea sized hail was reported in Esmond, Kirkland and Sycamore.

The main weather threat this morning is the locally dense fog.  This fog will last through the morning and likely holding on into the afternoon.  We'll continue with an east wind this afternoon which will keep the air mass at the surface stable.  But, just a few thousand feet above a warmer and unstable air mass is in place.

While we've missed out on the majority of rain the past couple of nights, that does look to change tonight.  Winds within the jet stream have been running from southwest to northeast.  Very subtle disturbances moving within the jet stream have produced severe weather across the Plains and Ohio River Valley the past couple of days.

Tonight, a stationary front will pull closer to northern Illinois at the same time a stronger upper level disturbance moves through.  During the day today, severe thunderstorms will be focused mainly south and southwest of northern Illinois.  Areas south of a line from Chicago to Peoria to the Quad Cities and stretching southwest into Kansas and Oklahoma will have the highest threat for damaging winds, hail and tornadoes.

That threat will be focused further north on Thursday ahead of a cold front that will move towards Chicago by Thursday night.  This brings a window for severe weather in the Stateline between 2pm and 7pm.  Damaging winds, hail and even isolated tornadoes are all possible Thursday afternoon, but the biggest question for Thursday will be how quickly thunderstorm development from Wednesday overnight/Thursday morning will clear out.  The quicker we clear, the higher the likelihood for severe weather.  Both myself and Meteorologist Kristin Cwynar will provide updates on our severe potential, so make sure you keep checking back.  This could be the first big severe weather event we've had in quite some time.  Now is the time to plan and prepare.  Make sure you know where your safe place is in your house or workplace.  Also, make sure you have a way to receive warnings - whether it be on your phone or with NOAA Weather Radio.