While I don't think that the flooding in Colorado was unprecedented, it was unusual.
But the reality is that we plan for what we can see, and (sometimes) fail to plan for what we cannot.
Is all yer stuff in a basement?
Got a sump pump? Have a spare? A means to power it? How about a manual backup?
Have you a secondary stash of supplies?
Have you gamed out all the "what ifs" you can and made plans for them?
The folks in Colorado obviously were caught unprepared....at least some of them. I doubt that they were all sheep either. Flash Floods happen quicker than you know. Now no doubt many folks never even considered that they were in a flash flood zone, or that rivers can and will leave their banks.
Living in or near a waterway OR DRAINAGE AREA is asking for disaster, especially if you are unprepared. Some towns are still cut off from the rest of us, as all their roads have washed away.
Think on it.