Despite average snowpack, Roaring Fork River runoff forecast to be below normal
Frigid late winter snowstorm could help runoff projections
The late-winter blast sweeping through the Roaring Fork River basin is boosting the snowpack to near average, but runoff is still expected to fall short this spring and early summer.
The high country received nearly a foot of snow by Tuesday evening and more was forecast to fall overnight with a winter storm warning set to run until noon Wednesday.
“Snowpack in the Roaring Fork basin was running slightly above average but has dropped back down to average for this date,” Don Meyer, senior water resources engineer with the Colorado River District said Monday as the storm was cranking up. “I don’t think this incoming storm will bring us back up above the peak (snowpack) to date, but time will tell.”
The snowpack for the watershed overall — the main stem of the Roaring Fork as well as the Crystal and Fryingpan rivers — was 98.6% of median as of April 1, according to the U.S. Natural Resources Conservation Service.
“(The Roaring Fork basin) fared rather well overall,” said Karl Wetlaufer, a hydrologist with the NRCS. “It was much better than much of the state.”
As of midnight Tuesday, snowpack ranged from 86% of median at the Independence Pass site to 112% at the Ivanhoe site at the Fryingpan River headwaters and 113% at Schofield Pass at the headwaters of the Crystal River.
The Upper Colorado River basin as a whole was at only 94% of median. Most other major river basins in Colorado were lower.
Meyer said this winter saw a typical weather pattern for a La Niña year. More snow tends to fall in the northern part of the state; less in the south, he said. Aspen and the Central Mountains can go either way.
It was feast or famine for long stretches of the winter for Aspen. The season started dry and then a strong storm cycle dumped snow across the region starting around Christmas and lasting into early January, Wetlaufer noted.
That was followed by a dry spell that lasted into February. The Roaring Fork watershed was among a part of the state that fared well with snowfall during the last half of February and through March. However, warm temperatures accelerated melting of the snowpack about two to three weeks earlier than usual, Wetlaufer said.
Snowfall at Aspen Mountain, Aspen Highlands and Snowmass was well above average during March, according to micro-forecasting service aspenweather.com. Snowmass recorded 72 inches of snow during the month, 131% of the average of 55 inches.
Aspen Highlands collected 68 inches during March. That was 124% of the average of 55 inches.
Aspen Mountain reaped 65 inches compared with an average of 49 inches. The total was 133% of normal, according to Aspen Weather meteorologist Corey Gates.
The city of Aspen water department recorded almost 32 inches of snow at the water plant. That was about 17.5% higher than the average of 27 inches, according to the monthly weather report.
Even with above average snowfall in March, the snowpack lost ground because of warm temperatures and melting.
Wetlaufer said the snowpack has likely already reached its peak because it has warmed through its depth and started melting. The frigid temperatures forecast for tonight and Wednesday night will temporarily delay melting but streamflow levels will soon start climbing, he said.
The Colorado Basin River Forecast Center projected April 1 that the volume of water flowing in the Roaring Fork River at Glenwood Springs during runoff from April through July would be 90% of average. By April 11, that had slipped to a forecast of 87% of average.
The forecast center indicated the runoff flow volume on the Fryingpan River at Ruedi Reservoir would be 88% of average, down from 93% forecast April 1.
The streamflow projections are lower than average even though snowpack is about average. That’s due to the dry conditions Colorado has experienced. All of Pitkin County was still rated in the “abnormally dry” level by the latest U.S. Drought Monitor map. Low moisture levels in soils soak in snowmelt before it reaches rivers and streams.
Wetlaufer said the runoff volume on the Roaring Fork River at Glenwood Springs was only 52% of normal last year, so a runoff volume between 90% and 95% this year would be welcomed.
“I would consider that good news, especially compared to the last couple of years,” he said. “At this point it depends so heavily on spring weather.”
Meyer said the current storm could change the outlook significantly. The outlook should be a lot clearer May 1.
“It’s really early right now,” Meyer said, “but we’re in a good spot compared to the rest of the state.”