Audio Script
Colorado鈥檚 biggest storms can happen anytime, CU-Boulder-NOAA study finds
5/20/2015听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听 Kelly Mahoney
People tend to think of weather in terms of seasons being drier or wetter than others, but according to a new study extreme precipitation events of rain, hail or snow can happen anywhere and anytime of the year in Colorado, says atmospheric scientist Kelly Mahoney, lead author of the study.
CUT 1 鈥淐olorado鈥檚 extreme precipitation can occur in any season and, really, at all elevations across the state. So trying to assign extreme events to a certain season isn鈥檛 necessarily a good thing to do here in Colorado. (:12) Very big storms can happen during any season and for those reasons it鈥檚 important for decision makers to understand that impacts such as flooding are a nearly year-round risk across the state.鈥� (:24)
Mahoney is a scientist with the Cooperative Institute for Research in Environmental Science, a partnership between CU-Boulder and NOAA. She says the study was done to improve the understanding of the state鈥檚 extreme event climatology.
CUT 2 鈥淏ecause even in regions where you think you have a strong seasonal signal the data actually show that the heavy precipitation events can happen outside of this sort of expected time. (:10) And that sort of logic is what we were kind of speaking to in this paper. That we really don鈥檛 obey the law of averages in Colorado when you come to the extremes.鈥� (:18)
Researchers found that the central mountains, along the crest of the Continental Divide, defied assumptions that the biggest storm events would happen during the winter, says Mahoney.
CUT 3 鈥淎long the spine of the Continental Divide there鈥檚 really no clear pattern. The common belief鈥攂ased on sort of historical averages鈥攊s that winter storms at the state鈥檚 highest elevations will produce big snow events. And that鈥檚 not necessarily what we found. (:15) Instead, high-elevation intense events have occurred during all months of the year there 鈥� again in those one-day totals - including the summer, which is interesting, because the precipitation at that time of the year is more likely to be rain and therefore more of a flood risk.鈥� (:29)
And the September 2013 flooding along the Front Range, says Mahoney, is more evidence that big storms can happen out of season.
CUT 4 鈥淎fter the September 2013 floods the sort of knee jerk reaction from a lot of people was, 鈥榃hoa! This happened in September. September is not a wet month for the Front Range.鈥� And that鈥檚 true when you look at seasonal averages. (:13) However, when you look at those precipitation ingredients coming together, September actually makes a lot of sense for our heavy one-day totals. So while it wasn鈥檛 typical, it certainly wasn鈥檛 unprecedented. There have been other past events in September.鈥� (:28)
For the study, researchers selected precipitation data from 130 weather observation stations throughout Colorado that had a record of at least 30 years of daily data between 1950 and 2010. At each station, the 10 largest daily rain totals were identified and used to characterize Colorado鈥檚 extreme precipitation by season. The study also includes researchers from Scripps Institution of Oceanography, Colorado State University and the U.S. Geological Survey.
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