Riding the Illinois Warm Front This Evening

Eating dinner with Colin after yesterday's chase I was pretty sure today would not be a chase day. Not into the messy mode on the surface low and cold front in Iowa and Missouri, we both figured the only way we were getting into chase mode was the very big if surrounding the Illinois warm front.

Illinois warm fronts are famous in storm chasing, but they're often not a sure thing. When they go, they go, but when they don't, you're out there chasing rain showers wondering what you're doing with your life.

This one looks like it's got the juice though. Tons of moisture pooled near and south of the warm front with dew points in the mid to upper 60s, pushing 70 in south-central Illinois. Instability will be abundant, including in the critical lower levels on a setup like today where you're dependent on stretching the ambient vorticity within the baroclinic zone - i.e. the air near the warm front will have lots of spin, and the faster you stretch that spin the harder it will want to rotate.

Going all the way back to Tuesday, the 12km NAM was dropping a big convective signal along the Illinois warm front in west-central Illinois at 78-84 hours out from the event. Last night the HRRR was showing specs of convection along the warm front as it lifted north across central Illinois but I was tired from several long days and short nights stacked in a row this week and happy to dismiss it as messy/junky.

After a few hours of sleep and my early morning alarm I sat down at my desk to crank out the morning forecast and was jump-scared by the HRRR and other CAMs going pretty aggressively after rotating storms lifting with the warm front across central Illinois.

And now here we are, a little after 1 PM. I've got my work day to-do list done and early morning alerts sent out and am starting to load the car back up. The most consistent signal for a supercell + tornado potential has been off to my west, probably about 2 hours down Interstate 72 toward Jacksonville IL, perhaps as far west as the IL/MO border near Quincy. The HRRR and other high-res guidance has been very consistent with a sustained supercell in this zone from around 5-9 PM.

I can't shake the feeling another supercell or two may pop up further east, closer to home and east of the Illinois river in potentially, or very likely better terrain and road network. Closer to home is objectively nicer most of the time, but I also don't want to miss out on the storm of the day because I was splitting hairs over 70 miles of driving.

Interstate 72 is one of my favorites, it's full of good vibes from past chase days, and because of that it often even feels like a chase day while I'm driving on it, even when it's not a chase day. I'm tired and quick to be like "ew, what, two hours of driving to the target? pass." and it's like, wake up Andrew, it's April, it's tornado season, and you can spend (probably at most) two hours driving on your favorite interstate toward a potential supercell and tornado this evening.

So, probably west on I-72 toward Jacksonville IL or so, but guarding the I-55 corridor from Springfield to Lincoln to Bloomington as well.