Colorado Snows Increase Flooding Concerns

ColoradoA rare May snowstorm blanketed parts of Colorado, Wyoming, and Nebraska on Mother’s Day and overnight into Monday, bringing over a foot of snow in some places and closing roads out into the Eastern Plains. Along the Colorado front range, the snow is likely to disappear within a few days; temperatures are predicted to rise into the 60s by mid-week and 70s by the weekend. However, as May moves into June and warm temperatures move into the mountains, many are increasingly concerned that this year’s above average snowpack will sharply increase the danger of flooding at lower elevations.

Counties north of Denver have become particularly vulnerable to flood damage. Early September of last year brought nearly eight straight days of torrential downpours that caused millions of dollars of damage to roads, houses, and low-lying areas, and resulted in four deaths. The amount of rain the area received was almost unprecedented; meteorologists called it the 1000-year rain and 100-year flood, the numbers indicating the expected frequency of such an event.

Colorado’s Front Range is particularly unsuited to handle such an excessive amount of moisture. Including snowfall totals, the area averages 20 inches of precipitation in a year, a number equaled by last year’s storms in only a week. Soil around the area was unable to absorb the moisture and pushed water down creeks and valleys, resulting in massive amounts of destruction. Several towns were completely cut off as roads above and below were washed out and, as of this spring, repair work is still not finished in many areas.

Of particular concern about this year’s runoff, Colorado’s High Country received a well-above-normal amount a snow over the winter. Some parts of the state reached almost 150 percent above average amounts, a boon for the ski industry and a change from recent years of troubling below-average snow totals. But the generous snowpack also increases the chances of a massive runoff, and many worry fragile areas still recovering from last year’s disaster could be hit again.

The melting snow is only part of the problem; last year’s rains filled reservoirs that are normally emptied for spring runoff, meaning there is no place to store this year’s water and forcing it to go directly down the creeks and canyons. The land around creeks has also lost most of its topsoil and is soft, meaning there is an increased chance of landslides that could wash away roads and entire sides of mountains. Towns could again be cut off, houses that survived last year could again be in danger of being washed down the river, and areas around the Front Range that have only barely recovered will again be at risk of being flooded.

Colorado officials are racing to do what they can to prevent potential flooding.  New reservoirs have been built, dams inspected and strengthened, roads reinforced or moved back as far as possible from creeks, and officials from towns vulnerable to flooding have been holding town-hall meetings to educate residents about what do if and when they have to again deal with rising water levels.

Nevertheless, only so much can be done in the short time remaining before the snows melt. The ever-increasing chances of flooding are at point few have ever seen and even if the state gets lucky and handles the early summer crisis, there is always a chance the skies could open up like last year and bring back the rains. It would be the final insult for a state used to snowy winters but dry summers.

By Andrew Elfenbein
@andyelf

Sources:
Boulder Daily Camera
Weather5280.com 
Aspen Journalism
The Weather Channel

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