It’s the middle of monsoon season in Summit County and, no, you haven’t just landed in Southeast Asia.
The rain the county received Monday, Aug. 4, created the wettest day of the summer so far, said Nolan Doesken, state climatologist with the Colorado Climate Center at Colorado State University.
Some parts of Silverthorne received more than an inch, and the rain total countywide averaged to about ¾ of an inch, he said, which is heavy for such an arid region.
The monsoon term you might’ve heard lately refers to a seasonally reversing wind pattern. Most people think of the copious amount of rain dumped on India and Bangladesh from the Indian Ocean, but a similar phenomenon also occurs in the Southwest U.S.
It’s called the North American monsoon, and it’s much weaker and more chaotic than the Southeast Asian version, Doesken said, because “we don’t just have one big ocean. We have Mexico dividing the air masses which come up from the Pacific on the west side and the Gulf of Mexico on the east side.”
West and northwest winds that normally howl on the High Country mountain tops and push around air high above the peaks are at their weakest at the end of July and early August, so that’s when tropical and subtropical moisture from either side of Mexico can arrive bringing classic afternoon thunderstorms and rain.
“Looks like Fourth of July sort of started the fireworks off,” Doesken said. “June was fairly dry, which it normally is up your way,” but in the last month, only seven days have been dry throughout most of Summit.
That brings good news for current drought conditions for communities that form the headwaters of the Upper Colorado River and the North and South Platte River. A snowy winter combined with steady precipitation in July means reservoirs on both sides of the Continental Divide are at or above normal levels for this time of year.
“We are for now drought-free” in Summit, Doesken said, so the next drought will belong to a new drought pattern. In this part of the country, “we’re either in drought, entering drought or exiting drought.”
The Southwest is still in the midst of a long-term drought as evidenced by water levels in Lake Powell, and much of southern Colorado is still experiencing drought conditions. Doesken said the state basks in generous water supplies only about 10 percent of the time.
“That’s why we have water managers,” he said. “Nature doesn’t do it that way.”
He called recent flooding on the Front Range “typical, seasonal, mostly local flash flooding” and said he hasn’t seen conditions anywhere close to what created hundred-year floods last September.
As for the forecast, he said to expect average temperatures and on-and-off showers for the next month, or “basically darn pleasant,” as opposed to any weather extremes.
The steady rain means reduced fire risk and should be a relief to wildland firefighters and residents living in and around forest areas.
“It’s preferable to be wet now and then than to be dry all the time,” he said. “Do your best to enjoy to it.”