Penn State e-wall website. Can you see it? It’s covering most of Wisconsin! MCCs are massive thunderstorm complexes that derive their strength from strong southerly flows of moist air from the Gulf of Mexico. True to form, this MCC set up north of a warm front and its radar signature is the classic round shape, with a nice cirrus outflow at the edges. I’ve written about MCCs several times in AOPA Pilot, and an upcoming Wx Watch in the July issue will address the subject again. MCCs have a nasty habit of persisting for days, so let’s see how this one plays out.