We'll know for sure in the next couple of hours when yet another line of storms comes through, but at the moment it looks like Chicago will break its May rainfall record today:
[T]he approach of yet another vigorous weather system spells more storms - possibly severe - for waterlogged northeast Illinois. Only 10.4 mm of additional rain will catapult this May's rainfall, currently 182.6 mm, to 193 mm and the wettest May in Chicago weather history.
Squish, squish, squish.