Yeah, flash floods was always a concern wheeling around San Bernadino county near the mountains from my experience. If we saw a trickle of water and there was rain/snow up in the mountains, keep an eye for that trickle to become a torrent pretty quickly.
Water fording is a tricky beast, by the book you need to be able to know what's under the water, often by getting out and wading across to get an idea of the layout then proceeding across carefully. With a flash flood you got a dynamic situation where you may have the "bed" being eroded away underneath the vehicle [or mud] and you may drop a foot or more instantly while crossing.
I had a wish list item of making sure I have a set of hip waders tossed in the tool box in case someone gets stuck in the muck.
I also make it a point if I play in the water, I do a service/fluids swap shortly afterwards. We're riding in many cases 10-20 year old vehicles, theres a chance a seal is going to ingest water at some point.
