These nocturnal storms for us (in Iowa) are usually part of a mesoscale convective complex or MCC. What are Mesoscale Convective Complexes? They are long lasting thunderstorm complexes that tend to dump a lot of rain usually in the Plains States (including Iowa). How do these form? They form from thunderstorm outbreaks usually on a convergence (such as a front or boundary of some type) They usually develop in the afternoon when daytime heating is at its greatest as it the instibility. This is when the greatest amount of severe weather occurs with an MCC. As the storms congeal, the severity of the storms lessen but the areal coverage of the thunderstorms grows and is carried along with the upper level winds (usually eastward, but depends on the upper level wind field at the time) They usually reach peak coverage around Midnight or so before starting to weaken. They can go a long way before eventually reaching an area that can no longer support the MCC. This could be either, no moisture (dry air), no instibility, no wind shear (High Pressure), or the atmosphere could have become stable (sunrise known to be the most stable time of the day for the atmosphere).

NOTE: This is what is likely to occur later this week along with the close but different MCS!

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