The risk for severe thunderstorms across central and southern Illinois today (Thu, Apr 18th) is not a new thing - there's been at least a slight risk across some portions of the area back to the Day 3 outlook issued on Tuesday morning. We're currently sitting with an enhanced risk and 5% tornado probability max over the southern 1/3rd of Illinois and a slight risk and 2% tornado probability north of I-72 into central Illinois. Sitting at my desk right now working away this morning I'm included in the slight risk/2% tornado probability.
The more I've sat with things this morning, the more this pit in my stomach has grown. A QLCS, perhaps with embedded supercells, traveling down a warm frontal zone along Interstate 72 in central Illinois in the month of April.
Could this line of storms become problematic and pose a risk for embedded tornadoes as it moves through central Illinois? Favorable low-level wind fields and loopy hodographs plus a vorticity rich baroclinic zone would certainly suggest so. The ceiling on the event from a severity standpoint will be how far north the warm front surges through the afternoon and how unstable the warm sector becomes. Forecast soundings from Springfield to Champaign, Illinois this evening show just enough instability and some subtle capping by late evening. It's extremely possible that the warm front doesn't surge north as currently advertised and/or thin clouds inhibit full destabilization and we see a messy, disorganized line of storms that poses no severe weather risk this far north.
Could this line of storms become photogenic and display jaw-dropping structure as it glides over the central Illinois farm fields at dusk? Once again, favorable wind fields in the lower levels now combined with some subtle capping would present the potential for a shelf cloud that appears "smooth" visually perhaps flirting with mothership appearances as it comes over the horizon. This scenario would largely be dependent on robust storms erupting across western Illinois and establishing themselves before any capping can set in. An established, robust QLCS would get a strong vote of confidence on my end to continue to ride eastward along the warm front, wherever it currently lay, well into the late evening beyond sunset.
Could this line of storms become problematic, and photogenic? That's the thing that gives me a pit in my stomach and has had me frantically clearing my busy family calendar for the evening. As it is, I'm free to roam, spectate, and provide severe weather coverage locally after 4:30 PM here in central Illinois.
Sometimes it really is that easy. A surging warm front with deep moisture and favorable wind fields in central Illinois in mid-April - am I really going to sit by and ignore that?
Evening storm observation goals: a photogenic shelf cloud at dusk, perhaps with a little extra kinky fun.