area I outlined yesterday. This was an area with limited instability, but intense lifting and helicity. A rapid refresh sounding for central Illinois near Springfield has only around 700 MLCAPE, but helicity over 800 m2/s2:
I made a 9 day forecast for this event which was one day late, and around 400 miles to the southwest.
Dew points were generally mid 50s in central Illinois to around 60 in southern Illinois.Here are some rapid refresh analysis charts from 12Z: