Rainfall Projections for Saturday-Sunday…..Flash Flood GuidanceAugust 30th, 2012 at 10:28 am by Chad Evans under Chad's WLFI Weather Blog
1-3″ looks like a good forecast for the area with a couple isolated 4″ amounts total from Isaac Saturday-Sunday-Monday. Right now, it does not look like flooding will be a big issue. It appears showers/some storms will arrive Saturday (up to 70% coverage late) with some Saturday night & additional showers & few storms Sunday (50%). A few showers/storms may pivot in Monday, but coverage then will run at 30%. A passing cold front will bring 30% coverage of showers/storms Tuesday, followed by dry, cooler, pleasant weather Wednesday-Friday of next week.
Why am I not talking up the flooding?
Below in the first graphic is a flash flood guidance graphic showing how much rain we could take on in a 6-hour period before we see flooding. You can see most of the area can handle 4″ in 6 hours, but anything above that in 6 hours would result in flooding.
In the second graphic, you can see that NOAA flash flood guidance shows that we could handle 3″ in 3 hours, but anything above that would bring flooding.
With largely 1-3″ over a 3-day period (isolated 4″ amount or two), such rainfall does not exceed the threshold for flooding in the area with current deficits & soil moisture (even with recent heavy rainfall).