Runoff news: Dust on snow events leave less mass than in 2010

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From The Denver Post (Jason Blevins):

Beyond the expected deluge, there is widespread worry about just how big the runoff could be. Lengthy stretches of hot temperatures could yield a tempest of whitewater that will swamp entire riverside regions. A healthy weather mix of cool and cloudy with warm and clear could stagger the surge, prolonging the season and keeping rivers roiling deep into July, August or even September. While no one knows what’s to come, at least one factor that has plagued Colorado’s runoff in recent years seems to not be playing as prominent a role this spring. For the last decade, windblown dust from the Colorado Plateau has painted Colorado’s peaks a reddish hue, absorbing sunshine and hastening snowmelt. This year is no different, with snow watchers counting nine significant dust events in Colorado. But unlike recent years, the density of the dust seems less this season…

But the lack of deeply darkened layers doesn’t necessarily exclude a deluge, warns Chris Landry, the executive director of Silverton’s Center for Snow and Avalanche Studies who has studied the impact of desert dust on Colorado’s snowpack since 2003. Dust layers merge as the snow settles and melts, creating incrementally darkening layers of snow that, once exposed to sunlight, accelerate the melt, Landry said. When warmth and sunshine reache that final layer, especially if it’s resting atop lots of water-laden snow, expect a deluge. Landry has recorded nine dust events across the state this spring but with “substantially less dust,” he said, especially in the northern and central ranges of the state. And “while every year is different,” Landry said, “there is an inevitability that at some point that final consolidated dust layer will come into play.”

From (Dann Cianca):

The Loma boat launch ramp was crowded on Memorial Day as rafters and kayakers hit the Colorado River. The flow of the river is quite high, however and those waiting to launch watched as large pieces of trees floated by in the rapid, silty water…The National Weather Service has issued a flood advisory for the stretch of river along the Utah/Colorado border as the river is at bankfull and could go higher in the next few days.

From (Jeffrey Wolf):

The National Weather Service is predicting that by Wednesday or Thursday, the runoff in north-central Colorado will begin in earnest. Its latest report indicates, “Drainages most susceptible to snowmelt flooding this spring include the Cache La Poudre, Big Thompson and Laramie Rivers in Larimer County; the North Platte, Illinois and Michigan Rivers in Jackson County; the Blue River in Summit County; the Colorado River in Grand County; and Clear Creek in Clear Creek County.”

From the Associated Press via The Columbus Republic:

Areas along the Green and Colorado rivers in eastern Utah are under a flood advisory. Forecasters say about two inches of rain have fallen since Friday. More than a foot of snow fell in higher elevations.

From the Fort Collins Coloradoan (Kevin Duggan):

A spike in temperatures forecast for later this week could launch what is expected to be a massive spring runoff on the Poudre River. The result could be flooding in areas with a history of problems during times of high water, including the McConnell Subdivision and County Road 5 near Timnath, said Erik Nilsson, emergency manager for Larimer County. Historically, runoff on the Poudre hits its peak around Father’s Day. This year, given that snowpack in the mountains is more than double of average for the time of year, the peak may come later, Nilsson said…

Flood stage at the mouth of Poudre Canyon is 7.5 feet or about 5,000 cubic feet per second, or cfs, according to the U.S. Geological Survey. Through Fort Collins, flood stage is 12 feet or 10,500 cfs. As of Monday afternoon, the river was running at 4.13 feet at the canyon mouth and about the same in Fort Collins.

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