Early July, still living in Las Vegas, huge storms broke out, water running down our street, west side of the city, was a foot deep. I saw news flashes on T-V of the parking lot at Caesar's Palace, part of which lies in a very large natural run-off wash. Devastation of cars parked there prompted me to run down for a look. A lot of cleanup was already completed by the time I took the first two pictures, below. The van in the second pic had New York plates! Signs strategically placed in that part of the lot, clearly warned of possible flash flooding. What, in Las Vegas? What a surprise for vacationers mal-parked there! The third pic is one from a newscast. It was a most memorable summer. A report on the storm is here: https://pubs.er.usgs.gov/publication/ofr76100
How about the flooding there this past Saturday - April 9th http://lasvegassun.com/news/2016/apr/09/strong-storm-hits-las-vegas-flooding-roads-and-dum/