There's a reason they are called "flash floods", they can happen so fast, warnings don't matter.
“”Why were people and dwellings allowed in the flash flood zone?””
Dwellings, hell. They keep showing a video of VERY high-dollar 2-3-story condos or homes completely surrounded by water right now. A lot of money was spent on construction and building exclusive “dwellings” right there.... in that flood zone. I suppose the buyers figured it hadn’t happened yet, so that meant that it wouldn’t happen. Surprise.