DENVER – Colorado is no stranger to severe weather during the summer months, but Wednesday night’s hailstorm in the eastern plains will no doubt be one for the record books.
“Didn't expect to wake up to reports of possibly the biggest set of hailstorms on a single day in state history, and most of it late at night,” tweeted Russ Schumacher, the Colorado State climatologist earlier Thursday.
You might wonder, “But why is hail newsworthy?” and you would be right – hailstorms in and of themselves aren’t that newsworthy in Colorado, but when they happen late at night and in bigger-than-usual numbers?
“That in itself, is the rarity of what we've been dealing with this entire severe season,” said Greg Heavener, the warning coordination meteorologist with National Weather Service (NWS) in Boulder. “The fact that we're seeing these storms develop later in the evening and that it’s causing all these impacts and issues, that’s not, you know, a typical Colorado severe season for us.”
Heavener said the majority of the storms we get in Colorado usually develop around 11 a.m. or noon across the high country and then kind of push off to the east throughout the Urban Corridor, followed by I-25 Corridor, and then farther east across the plains, basically moving east of the Urban Corridor by 4 p.m. or 5 p.m.
“The fact that this year, including last night, we've had three (hailstorms) now that have occurred (late at night) since really, mid-May, is rare for Colorado standards,” Heavener explained.
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Preliminary reports from the Colorado Climate Center (Schumacher serves as its director) showed at least 11 reports of hail over three inches in size (baseball-sized hail) and four reports of hail over four inches in size (soft ball-sized hail).
Schumacher said the last time hail over three inches in size was reported in a single day was on June 10, 2010, when only four reports came in that day.
Why is that a big deal? Because weather scientists consider hail up to 2¾ inches in size to already be “very large hail.” Anything over that is already classified as “giant."
“Really big hail late at night is also very rare in Colorado,” Schumacher wrote. “Before last night, there were only 5 reports of 3”+ hail between 11pm-11 am in 65+ years; last night there were seven.”
Heavener agreed.
“I think what's the rarity of it is, obviously the number of hail stones we got that we considered significant hailstones,” Heavener said. “The biggest rarity of it, though, is that it all occurred really late last night before coming into early Thursday morning.”
Hailstones that are two-inch in diameter (golf ball to baseball-size) are considered “significant,” per climatologist’s parameters. At that size, it’s going to do “some pretty nasty damage, especially if it’s wind-driven,” Heavener said.
“We're looking at two- and three-quarter inch diameter hailstones being blown horizontally by 70, maybe even 80 mph wind gusts into cars, into houses,” he said.
Reports of soft ball-sized hailstones came from parts of Morgan as well as Washington counties along the I-76 Corridor, Heavener said, with towns like Akron and Brush getting hit particularly hard by the hail somewhere between 11 p.m. Wednesday and 3 a.m. Thursday.
Both Schumacher and Heavener did warn though, there are some caveats when reporting on severe weather – especially when it comes to unusual events, because of the increase in population in any given area over the years, as well as access to technology that people didn’t have before.
“It's a little difficult to say if this was the most (late night reports) that we're aware of thus far, again, because reporting standards have increased and the volume of reports that we get these days is in order of magnitude – if not more – than say, what we got 65 years ago,” Heavener said.
For weather history buffs, the largest hailstone to have ever fallen out of the sky in Colorado happened back in August 2019 in Bethune (Kit Carson County). That hailstone was recorded as a 4.83 inches in diameter, according to Heavener.
While it seems like we’ve gotten a lot of hail this year, he said this severe weather season is on par to what we would typically see for Colorado in the summertime. What’s more atypical is the number of large hailstones and that they’re happening late at night.
Still, Schumacher said this year's severe weather season will go down in history.
“Between last night’s storms and those earlier in the month, June 2023 will surely go down among the biggest months for hail in Colorado records.”
Editor's note: A previous version of this story stated the record-breaking hailstone that fell north of Bethune was recorded at 4.6 inches in diameter, but that is incorrect. The hailstone measured at 4.83 inches in diameter at its widest point.
