Hail — and the physical and economic damage that comes with it — could be gone from Colorado’s Front Range by 2070, say Boulder scientists.
Not having hail to deal with would be a boon to gardeners and farmers. But a shift from hail to rain can also mean more runoff and a greater risk of flash flooding, said Kelly Mahoney, a research scientist at the University of Colorado’s Cooperative Institute for Research in Environmental Sciences.
“In this region of elevated terrain, hail may lessen the risk of flooding because it takes a while to melt,” she said. “Decision-makers may not want to count on that in the future.”
The hail study was conducted by CIRES, the National Oceanic and Atmospheric Administration, and the National Center for Atmospheric Research.
For the study, published this week in the journal Nature Climate Change, Mahoney and her colleagues used “downscaling” techniques to try to understand how climate change might affect hail-producing weather patterns across Colorado.
The research focused on storms involving pea-size and smaller hailstones on Colorado’s Front Range. The state’s most damaging hailstorms tend to occur farther east and involve larger hailstones not examined in the study, said researchers.
In all, over the past 10 years, hailstorms have caused more than $3 billion in insured damage in Colorado, according to the Rocky Mountain Insurance Information Association.
Mahoney and her colleagues have been exploring how climate change may affect the amount and nature of precipitation along the Front Range. They paid particular attention to the safety of mountain dams and flood risk.
They started by looking at the results of two climate models, which assumed that levels of climate-warming greenhouse gases will continue to increase in the future, from about 390 parts per million in the atmosphere today to about 620 ppm in 2070.
However, they found that the weather patterns that form hail occur on much smaller scales that can be reproduced by global climate models, the researchers said.
So the team “downscaled” the global model results twice — first to regional-scale models that can take regional topography and other details into account, and then to weather-scale models that can resolve individual storms and even the cloud processes that create hail.
Finally, the team compared the expected hailstorms of 2041 to 2070 with those from 1971 to 2000, as captured by the same sets of downscaled models. The results were similar.
“We found the near elimination of hail at the surface,” Mahoney said.
Future storms along the Front Range may become more intense and produce more hail inside clouds, the team found. But because those relatively small hailstones fall through a warmer atmosphere, they melt quickly, falling as rain at the surface or evaporating into the atmosphere.
The last hail-related fatality in the U.S. was in Lake Worth Village, Texas, on March 28, 2000. A 19-year-old man was struck by softball-size hail while trying to move a new car. He died the next day from head injuries.
Monte Whaley: 720-929-0907 or mwhaley@denverpost.com
