I've been keeping an eye on Ivan. My girlfriend lives in Spring and her neighborhood floods in a spit of rain. 20"? I'm not seeing this myself. Maybe a few spots over the next five days around 10-12 locally. I have not seen a single piece of guidence or, for that matter, the look of the system on radar that tells me it is capable of dumping 20" in a single spot. Unless it absolutely parks for a few days and trains over one particular area, I really think 10" will be max with a general coverage of 2-7". Granted, with the conditions, that is still enough for widespread flooding; but for a local met to be saying 20" is a little sensational. Flooding will be a serious problem even with 2-4", though.