It's cloudy, breezy, and overcast out the window in Champaign-Urbana, IL with the driveway thermometer reading 63.7 deg F and rising. The pavement is sweating with warm air and moisture advection continuing through the overnight hours. It's a chase day.
The Storm Prediction Center has maintained a broad slight risk area with a 5% tornado risk and 15% hatched risk for hail over 2". High-resolution forecast models continue to depict what looks like two primary zones for severe thunderstorms over the next 24 hours.
First, scattered severe storms should develop near the intersection of a surface low, cold front, and dryline feature across north-central Illinois late in the afternoon and evening hours. Given favorable thermal and wind profiles in the area a few intense supercells producing hail over 2" in diameter may develop. Additionally, storms that are able to develop further east along the approaching dryline bulge away from the encroaching cold front will have a relatively greater tornado potential. These storms may eventually move into the greater Chicago metro, and should a higher end solution manifest, additional supercells may develop along the same boundary into northwest Indiana. If this happened, storms across northeast Illinois and northern Indiana would all carry this large hail and tornado potential as the low-level jet ramps up and hodographs become long and loopy.
A second zone emerges tonight closer to the 500 mb jet streak across the Ohio River Valley. Confidence in this threat region will probably increase/decrease through the day today, but I would not be surprised to see one or two intense supercells tracking through southern Indiana or nearby portions of southern IL, northern KY, and southwest OH late tonight. I think the hail potential would be slightly lower in this southern region, but you could tick the potential for a longer track, stronger tornado upward across this area.
All in all, while storm coverage may limit the overall extent of this one, there is certainly potential for a memorable supercell to occur across the Midwest over the next 12-18 hours.
I'll be sitting in Champaign-Urbana for another hour or so finishing up some work and making sure all parties that I'm responsible for have been alerted to the severe weather potential and then I'm off. I've obviously got to keep the backyard honest, but I'm definitely being lured northward a bit. I think the I-80 corridor from Interstate 39 eastward into northwest Indiana is really interesting... confidence in a daytime supercell in this area is lower, but IF that storm formed, there's no other storm I'd rather be on today.
Even if the tornado potential falls short today, if you told me that on February 27th of this year I'd have the opportunity to go chase some hail producing supercells in-state, I'd be over the Moon. We'll go with the big white 'X' for an early target zone. This affords me the opportunity to bail west to hail producing storms on the cold front if they're the only game in town, or access to supercells across northeast Illinois and northwest Indiana that should carry a higher tornado potential IF they exist.
Good luck if you're headed out today! Chase smart, tripod your cameras, and don't talk to me when I'm filming my storm.