USA: Colorado - the art and science of planning for heavy rains

Colorado State University (CSU), USA researcher and State Climatologist, Nolan Doesken, asks whether the structural resilience of Colorado's buildings will be able to withstand the potential impacts of climate change and if the county is prepared.

An extract from Colorado Water, a newsletter of the Water Center of Colorado State University, March / April 2010,  Volume 27, Issue 2

The climatology of heavy rains in Colorado by Nolan Doesken, Colorado Climate Center, Department of Atmospheric Science, Colorado State University.

'Fortunately for Colorado, it has now been over 10 years without another extreme precipitation event. But our history tells us that it’s only a matter of time before the next extreme storm hits, and it will most likely be somewhere along the Front Range—where the intersection of mountains and plains tends to focus and exacerbate flood-producing storms. Will we be ready?

What Comes Next? That, of course, is the big question. A clear finding from past rain gauge and streamflow data is that Colorado’s largest storms and most extreme flash floods occur at elevations below about 7,500–8,000 feet, primarily east of the Continental Divide. This is because the bulk of the moisture in our atmosphere is transported in the warmest layers in the nearest few thousand feet above the ground, and the greatest sources of moisture come in summer air masses that originate near the Gulf of Mexico or across the humid Midwestern states. But if the atmosphere continues to warm, there could periodically be more water vapor available to fuel extreme storms at higher elevations, both east and west of the Continental Divide. If this were to happen, we might see more extreme rain events at higher elevations that would lead to dramatic flash floods. Climate scientists and hydrologists are not sure this will happen, but it could. Are we ready?'