#Snowpack / #runoff news: Conditions should improve this weekend

Westwide SNOTEL map April 14, 2016 via the NRCS.
Westwide SNOTEL map April 14, 2016 via the NRCS.

From the Vail Daily (Scott N. Miller):

At the moment, snowpack looks good on Vail Mountain, Fremont Pass and at Copper Mountain — the closest snow-measurement site to Vail Pass. That’s good news, since much of the upper valley’s water supply is stored in snowpack, not reservoirs.

As of Monday, those three snow measurement sites were all within 5 percent of the 30-year historic median levels. That’s good, since we’re within a week or so of the historic peak of what’s called the snow year — roughly Nov. 1 through May 1…

STATUS OF RESERVOIRS

Peter Goble, of the Colorado Climate Center at Colorado State University in Fort Collins, said Dillon Reservoir is at roughly 90 of its average capacity for right now. But fresh water there will be diverted down the Blue River to Green Mountain Reservoir, which is currently at 40 percent. Granby Reservoir, near the Colorado’s headwaters, is releasing water into the river at normal rates right now, Goble said.

STORM HEADED THIS WAY

While snowmelt is on the minds of river-runners and others who depend on water levels right now, it looks like there’s still more precipitation to come.

Dennis Phillips, a meteorologist with the Grand Junction office of the National Weather Service, said a good-sized storm is headed for Colorado from the Pacific Northwest. That storm should hit in the next few days, Phillips said.

More important, Phillips said a low pressure system is expected to set up and stall over the Four Corners area. That system should remain into early next week.

That means there’s a good chance of precipitation, some of it heavy at times.

LOOKING INTO THE FUTURE

Weather forecasting loses a lot of certainty more than about 10 days into the future, but the weather service does do longer-term forecasts, based more on probabilities than actual patterns.

This year, the probabilities look pretty good for a slow, sustained snowmelt. Phillips said the 60-day outlook shows this part of Colorado with an above-average change of above-average precipitation and below-average temperatures. Looking further out, the 90-day outlook shows an above-average chance of above-average precipitation and above-average temperatures.

That came as good news to Eagle River Water & Sanitation District communications and public affairs manager Diane Johnson.

“If it gets to mid-June and warms up, that would be great,” Johnson said. “That means we’ve had a nice, slow snowmelt.”

From The Pueblo Chieftain (Matt Hildner):

Time is running out for snowpack to rebound in the Rio Grande basin but forecasters are optimistic the San Juan Mountains will still get above-normal precipitation in April and May.

The prospect of late spring snow, especially after a 45-day run with almost no snow in February and March, would be ideal, said Pat McDermott, a staff engineer for the Colorado Division of Water Resources in Alamosa “Late April and May snowstorms have a huge impact on this basin as far as runoff,” he told the Rio Grande basin roundtable.

Precipitation to date is at 82 percent of average in the basin but the National Weather Service’s long-term forecast calls for above-average precipitation in April and May.

The arrival of that snow would be good for irrigators come summer, but it would also impact how the state manages its deliveries under the Rio Grande Compact.

The compact, which divvies the river’s flows between Colorado, New Mexico and Texas, has sliding delivery requirements for Colorado that vary according to the amount of streamflows.

Right now the state predicts 645,000 acrefeet of flows on the Rio Grande at Del Norte, which, if true, would amount to 104 percent of the river’s average.

That would require a delivery obligation of 180,000 acre-feet and has led the state engineer’s office to set curtailments on irrigators at 13 percent…

On the Conejos, the San Luis Valley’s second biggest river and a tributary of the Rio Grande, the projected streamflow for the year is 280,000 acre-feet.

If that projection holds, it would be 93 percent of the river’s long-term average, according to records that date back to 1910.

The delivery obligation sits at 95,000 acrefeet, while curtailment is set at 22 percent.

From The Pueblo Chieftain (Chris Woodka):

Will another “Miracle May” quench the thirst?

Impossible to tell in mid-April, when conditions are mirroring those seen last year.

Snowpack in the Arkansas River basin is just 80 percent of average, but ahead of last year at the same time, Water Division 2 Engineer Steve Witte told the Arkansas Basin Roundtable this week.

Reservoirs are full — so full that the only reason more water is not being spilled is the abnormally dry March weather. Until a soaking shower in Pueblo on Sunday and Monday, Pueblo had been parched. Now, rainfall for the year is about normal, and conditions are expected to stay wet for a while.

Styling his talk “State of the Arkansas,” Witte delved into the statistics that paint a picture of unsettled conditions.

“In January things looked good, and I said the drought was over,” Witte joked. “By early April, things had declined. But remember last year when we had a Miracle May and Pueblo got a record 5.6 inches in one month.”

The best result was that reservoirs topped off.

The worst result was that those who had prudently saved water those reservoirs might lose it.

On March 2, Lake Pueblo held 272,000 acre-feet of water, which meant a lot of it could have been lost in order to get to the proscribed flood control volume of 245,373 acre-feet on April 15. Fortunately, the dry weather allowed about 25,000 acre-feet to be used in late winter and early spring, ending that threat.

For now.

“Unless we get another Miracle May,” Witte said.

John Martin and Trinidad Reservoir are also at the highest levels in years, providing assurance that even if the rains don’t come, the Arkansas Valley will be in relatively good shape this year.

From Steamboat Today (Tom Ross):

The Yampa River was flowing at more than three times the median volume for April 14, but a meteorologist at the National Weather Service in Grand Junction confirmed the rushing river was rising due to rapid, low-level snowmelt, and the peak of spring runoff is likely still well in the future.

The Yampa was flowing at 1,650 cubic feet per second at mid-afternoon Thursday after dropping from its daily peak of 1,790 cfs, recorded by the U.S. Geological Survey just after midnight. Those flows compare to the median flow for April 14 of 470 cfs.

“About a week ago, the Yampa began to show a general trend upward with daily swings,” NWS forecaster Dennis Phillips said. “There was a surge with temperatures getting so warm, we saw water run off throughout the night. Low elevation runoff could crest soon.”

Consulting forecasts by the Colorado Basin River Forecast Center, Phillips said the expectation is that the nearby Elk River, which drains the west side of the Mount Zirkel Wilderness Area, should peak on or near June 1. A similar long-range forecast for the Yampa hasn’t been posted.

With a colder storm front due to influence weather in the Yampa Valley for the next four days or so, the forecast center anticipates the Yampa will calm down, with flows gradually receding into next week, Phillips said.

Historical data collected by the U.S. Geological Survey confirms how unusual this week’s flow on the town stretch of the Yampa has been. The record flow for April 14 on the Yampa at the Fifth Street Bridge was the 2,070 cfs, recorded in 1930. Not since the 1,810 cfs (mean flow for the entire day) recorded on April 14, 2000, has the Yampa seen anything similar to April 2016.

The mean flow April 14 in many seasons is in the range of 300 to 500 cfs, according to USGS records.

yampariveratsteamboat04152016

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