DENVER, Oct. 11 (UPI) -- As hail season ends in the "hail alley" states east of the Rocky Mountains, weather scientists say these destructive storms appear to be increasing, causing greater property and crop damage and injuring more people and animals.
In 2019, extra-large hailstones measuring 3 inches or more in circumference fell during storms in Colorado, Nebraska, Kansas and Texas this spring and summer, the National Oceanic and Atmospheric Administration reported. A total of 176 episodes of severe hail were reported in those states, plus South Dakota, Montana and Wyoming.
In August, a severe storm with baseball-size hail and 70-mph winds killed between 11,000 and 13,000 waterfowl at a Montana marshland in Yellowstone County. Dead and injured pelicans, cormorants, geese and ducks were scattered around the Big Lake Wildlife Management Area north of Billings, according to state park officials.
"We walked up and saw dead birds strewn across the shoreline and injured birds with broken wings," said Justin Paugh, wildlife biologist for Montana Fish, Wildlife & Parks.
"Once we saw divots in mud on the bank of the lake like golf balls, it came together pretty quick that these were hail fatalities. I've never experienced anything of that magnitude," Paugh said.
States east of the Rocky Mountains are more subject to severe hail-producing weather because of mountain-influenced wind patterns and a change in humidity when wet air from the Gulf of Mexico hits the arid prairie landscape, according to a study by the Fort Collins-based Colorado Climate Center published Aug. 29 in the Journal of Applied Meteorology and Climatology.
"Warm, moist conditions are favorable for severe weather," said Russ Schumacher, head of the climate center. "There's more instability in the atmosphere, and storms that form are even stronger and capable of producing really big hail."
The amount of hail-caused property damage in the United States has been increasing, insurance groups say. In the past three years, the number of insurance claims for hail damage spiked by 19 percent, according to the Illinois-based National Insurance Crime Bureau.
In 2016, insurance policyholders in Texas reported 378,652 claims, with the most damage to cars and personal property in San Antonio, where 68,778 claims measuring $1.4 billion in losses were filed.
Although state totals are not available for this year, damage in Collins County, Texas, alone is expected to be more than $300 million, NOAA records indicate.
Colorado has a smaller population than Texas, but is situated next to the Rockies, where weather patterns can be severe. The state has seen an increase in severe hail weather events starting in 2016, Schumacher said.
In Colorado Springs alone, heavy hailstorms in 2016 and 2018 added up to 66,467 claims, totaling almost $522 million, the insurance bureau reported.
In August 2018, a quick-moving storm pelted baseball-size hailstones onto the Cheyenne Mountain Zoo in Colorado Springs. Fourteen people were injured and at least three zoo animals killed by the giant hailstones.
At nearby Fort Carson, a U.S. Army base, hailstones destroyed every roof on the base and smashed cars in the parking lots, causing almost $60 million in damage, Brandy Gill, chief of media relations, recalled.
"Some of the cars looked as though they had been in a rollover wreck," Gill said. "Back windows, side windows, moon and sun roofs -- those were gone. The housing on the installation had holes in the sides of the buildings and windows in buildings were broken.
"The storm only lasted 15 minutes, but with those size hailstones that's a lot of damage."
16 inches of hail
In early September, a Colorado thunderstorm dropped 16 inches of small pea-size hail stones on the area near Lake George, killing at least one pronghorn deer fawn, Colorado Parks and Wildlife reported.
So-called "snow plow" hail, so deep authorities have to break out the shovels, often doesn't even register on NOAA's severe storm reports, but it can cause damage, the climate center's Schumacher said.
There is no official count of wildlife killed in hailstorms, unless storms happen on state park land, Paugh said. "We sometimes get reports of birds like pheasants or antelope fawns, but we don't really track the deaths," he said.
The largest recorded hailstone in U.S. history fell from the sky in July 2010, in Vivian, S.D.
The megastone, displayed in a freezer at the National Center of Atmospheric Research in Boulder, Colo., measured 8 inches in diameter and weighs 1.94 pounds.
To calculate the increase in hailstorms, climate center scientists are trying to capture the big picture of hail events in the Rocky Mountain corridor.
"Obviously, a farmer can't move his field, but if we can better understand how hail develops, people can move their cars or take other action to be safe," said Sam Childs, a doctoral candidate at Colorado State University who co-authored the new study.
One challenge has been that hail is measured by the damage leaves -- to human dwellings, cars and crops -- which does not capture the all hail activity.
"Hail is only reported where people live or on major thoroughfares," Childs said.
Tracking and predicting hail is notoriously tricky for weather scientists.
Hail falls randomly and erratically when spiraling supercell thunderstorms up to 3 miles tall create warm updrafts that blow drops of rain up into below-freezing storm clouds.
Hailstones freeze and refreeze, gaining size until they are finally heavy enough to fall through the wind currents to the ground.
Hailstorms can ruin one farmer's crop and leave a neighboring farm unscathed.
A June 2018 a fierce storm in Niwot, Colo., flattened 11 acres of vegetables and 7 acres of heritage wheat at Aspen Moon Farms in a half-hour, owners Erin and Jason Griffith said in an online fundraiser.
Calling the storm a "devastating blow" and a "real tragedy," friends raised money to repay the Griffiths' end-of-season farm loans -- "loans that would have been paid with the crops that the hail destroyed," friend Daniel Hindes said.
Farmers can recover some of their crop losses through the non-insured disaster assistance program offered by the U.S. Department of Agriculture's Farm Service Agency, said Brandon Terrazas, Denver-area district director of the farm agency. Other crop-hail insurance coverage is sold privately and backed by the USDA's Risk Management Agency.
"We see hail claims more with fruit and vegetable growers than with grain farmers, who are eligible for privately administered crop insurance," Terrazas said. "Our adjusters look for the signs of hail, holes in the leaves, fruit knocked on the ground. They use weather information to verify the claims."
But insurance only covers a part of the lost crop's initial costs, not the loss from anticipated sales.
"Farmers can recover maybe 50 to 60 percent of their costs. They are never really made whole," Terrazas said.
High- and low-tech tools
Scientists and insurance companies are developing new tools, like artificial intelligence and drone surveillance, to predict and verify hail damage.
National Center for Atmospheric Research scientists at the University of Oklahoma have developed over the last three years a machine-learning model to analyze images from storms and match them with actual measurements of temperature, pressure, wind speed and direction to see which storms produce hail and how big the hailstones are.
The new computer program can't precisely predict hail yet, but machine-learning scientist John Gagne said in a press release that the new method had "a lot of promise to help forecasters better predict a weather phenomenon capable of causing severe damage."
Flying drones after thunderstorms can capture hail damage patterns before the hail melts, especially in rural areas, the climate center's Schumacher said.
"You get out your ruler and send us the photos," he said.
Finally, weather scientists are trying to develop models to project hail damage with different population scenarios, Childs said.
"On the Great Plains, in general, we can predict increasing trends that make an environment favorable for more hailstorms in the future," he said. "We'll see whether change in climate or change in numbers of people living here will correlate to economic loss and damage."