My family moved to Boulder in the summer of 1968. On May 5-9, 1969, hard rains produced the biggest flood in decades. As a 7-year-old the 3 feet of water in our (unfinished) basement seemed super cool, sort of like having an indoor swimming pool.
Growing up in Boulder the “100 Year Flood”, was part of the local lexicon, like fallout shelters were for families in the 60’s; one of those legendary things that can’t really happen. We know about these things and plan for them, right? Every summer at 10 a.m. on the first Monday of each month, Boulder tests its emergency warning system – deafeningly loud sirens and a booming voice over the loudspeakers chillingly announcing, “THIS IS A WARNING SYSTEM TEST.”
But on September 12-15, 2013, when the proverbial “100 Year Flood” actually happened, it was a shocker. For one thing, no one ever thought a big flood would happen in September, when summer monsoon storms typically taper off and thunderstorm producing convection is weak. This year the monsoon was stubborn, and a confluence of static weather systems and particularly abundant monsoon moisture produced a cataclysm that the typically subdued National Weather Service forecasters termed “biblical”.