Local area an exception to statewide drought conditions
By Bob Berwyn
FRISCO — Summer precipitation was a mixed bag in Summit County, with above average totals in July but less than average rainfall in August, as the monsoon rains petered out. Statewide, conditions remained very dry, with the exception of a small pocket of the high country centered on Eagle, Summit and Lake counties, as well as parts of the San Juans.
Breckenridge-based weather watcher Rick Bly reported 4.21 inches of rain in July, well above the average 2.32 inches. That moisture boosted the year-to-date total to 92 percent of average, amazing considering the widespread drought conditions in Colorado.
More than 1 inch of that rain came in a single 24-hour period during a particularly heavy mid-month downpour.
“It’s only the sixth or seventh time I’ve recorded over an inch of 24-hour moisture in July,” Bly said. “It seems like we’re having bigger events.
Bly’s observation ties in with global weather patterns, which have been trending to more extreme events — heavier rainfall, sustained blizzards, cold spells and drought — all believed to be linked with a warming climate.
Even with the dip back down to below normal totals in August, year-to-date precipitation was still at 91 percent of average in Breckenridge, a small regional anomaly in the statewide picture.
Only three months of the weather year have brought above-normal precipitation: January, February and July.
September generally brings dry conditions, with average precipitation of 1.74 inches and average snowfall of 4 inches, though there have been some big dumps during the month. The record snow for September is 53 inches, in 1961, but there have been many Septembers with no snowfall.
At Summit County’s second official weather observation station in Dillon, moisture trends were similar, with 3.17 inches in July, well above the historic average (records going back to 1909) of 1.88 inches.
August precipitation at the Dillon site, at Denver Water’s Dillon Dam headquarters, was 2.60 inches, also well above the average of 1.77 inches. Compared to Breckenridge, that reading shows how fickle summer rains can be.
July also lived up to its reputation as the warmest month of the year in Summit County. The average maximum daily high at Dillon was 76.1 degrees, nearly 2 degrees higher than the historic average (74.3 degrees).
The average daily minimum temperature was 41. degrees, also well above the historic average of 37.3 degrees. That pattern persisted in August, with daily highs averaging out to 73.6 degrees, which was 1.1 degrees above the historic average. August lows averaged to 38.3 degrees, more than 2 degrees above the historic average of 36 degrees.
July and August are the only months when daily lows average above freezing. September generally brings a big cool down, with the average daily low dropping to below freezing, at 28.7 degrees.
The wet conditions the past few months could give the illusion that the drought isn’t quite so bad, but a look at streamflows shows that the rains offered only slight and temporary relief.
“Every one of our creeks and streams is still a third, at best, of median historical values,” said Troy Wineland, Blue River Basin water commissioner for the State Engineer’s Office.
Many local streams flirted with historic low flows during the summer. Looking back over historic records, Wineland said the only other time streamflows hovered in a similar range were in the 2002-2003 drought.
When temperatures start to dip below freezing at higher elevations, some streams may yet dip to record low levels, and some of the ski areas that rely on direct withdrawals from streams may face challenges meeting minimum streamflow requirements.