Spring runoff could kick in this weekend on Yampa River in Steamboat Springs

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— The Yampa River at Steamboat Springs was flowing Monday at levels more typical of April 1 than of April 22, but that’s about to change.

The Colorado Basin River Forecast Center predicts the river’s flows will begin to climb steeply Friday as spring runoff season begins in earnest. The Yampa River could reach 600 cubic feet per second in downtown Steamboat by Saturday night.

The river was flowing Monday at a modest 282 cfs where it passes beneath the Fifth Street Bridge, compared to the median flow for the date of 756 cfs.

River Forecast Center hydrologist Brenda Alcorn said the prediction is based on expectations that temperatures will become more seasonable later this week and become even milder by the weekend. The National Weather Service in Grand Junction forecasts a Thursday afternoon high of 55 degrees under sunny skies. Mild weather will continue through the weekend, when it could be 60 degrees both Saturday and Sunday.

The river is expected to stair-step up toward 1,000 cfs by May 2, just about 60 cfs below the historic mean for the date. The River Forecast Center also expects the Elk River to begin to rise Friday, but at a more gradual pace, reaching 800 cfs by Friday night.

Alcorn said that as of a week ago, her Salt Lake City-based agency gave the Yampa a 90 percent chance of peaking at flows greater than 1,350 cfs, but just a 25 percent chance to surpass 3,000 cfs and come close to the historic median runoff peak of 3,070 cfs.

“Those numbers have probably changed from a week ago,” Alcorn said. “The peaks are really dependent on spring temperatures.”

As of April 15, the Elk River was given a 90 percent chance of peaking above 1,500 cfs at its confluence with the Yampa, and a 75 percent chance of surpassing 1,700 cfs. The Elk was given a 50-50 chance of peaking above 2,200 cfs. The Elk peaked just above 7,000 cfs in the record runoff year of 2011.

The Yampa at Steamboat peaked at 1,570 on April 27, 2012, foreshadowing a drought pattern that persisted through most of the summer. But the snowpack surrounding Steamboat, while still below average for the date, is healthier than it was a year ago.

Mage Hultstrand, assistant snow survey supervisor with the Natural Resources Conservation Service in Denver, said Monday that the late-April snow has definitely made a difference in the statewide snowpack.

“It’s a huge improvement,” Hultstrand said. “The colder temperatures have been delaying runoff and we’ll have water in our streams way later than we would have.”

However, April snow doesn’t have the endurance of the snowpack that accumulated throughout the heart of the winter, according to Hultstrand. And although the snow-water equivalent in the combined Yampa and White river basins currently stands at 97 percent of average for the date, the number is a little misleading. That’s because today’s snowpack is being compared to historic numbers recorded at a time of year when the snow is already running off the mountains. It’s more accurate in late April to compare the snow-water content to the median peak for the season.

In those terms, the snowpack now stands at 89 percent of median, Hultstrand said, still greatly improved over April 1, when it was 78 percent of the median.

When temperatures warm up later this week, the recent snow is apt to run off at a faster rate than the condensed snowpack from earlier in the winter, Hultstrand said.

“We don’t have that big base that’s been sitting up there for a long time,” she said.

To reach Tom Ross, call 970-871-4205 or email tross@SteamboatToday.com

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