Common Dreams reports
A Maryland city was devastated [May 27] after 6-inches of heavy rain caused a downtown flash flood. Major damage is reported and many cars have been swept away.
Ellicott City was still recovering from a flash flood two years ago that killed two and forced the historic city to rebuild much of its Main Street. Residents said Sunday's flood seemed even worse than the storm in July 2016--which was called an extremely rare "one-in-1,000 year event", and cost the city tens of millions of dollars in damages.
Additional information at:
The Baltimore Sun
The Washington Post
USAToday
(Score: 2) by HiThere on Tuesday May 29 2018, @06:38PM
It's an estimate of the probability based on that data available at the time it was calculated. It's also highly rounded. You don't see reports of "it's a 1 in 997 year flood".
The numbers aren't updated as frequently as they should be, but even if they were you shouldn't take them that seriously...they aren't intended to be taken that seriously. They are *estimates*.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.