Here’s the release from the Natural Resources Conservation Service (Brian Domonkos):
While Colorado did receive some mid-month precipitation accumulation, January received below average accumulation to the snowpack. This has been an unfortunate trend throughout the water year after a dry summer. Recent snow accumulations brought statewide snowpack back up to 77 percent of median and water year to date precipitation to 69 percent of average, as of February 1st. NRCS Hydrologist Karl Wetlaufer remarks “While it has been a dry water year so far, there are still two months left in the normal snow accumulation season which leaves time for this pattern to potentially change”. Several years in the recent past have observed substantial late spring and summer precipitation. While this isn’t anything to count on it can be a possibility for the snowpack to still recover to more normal levels.
Reservoir storage varies widely in the state from a low of 60 percent of average in the combined San Miguel-Dolores-Animas-San Juan river basin to a high of 106 percent in the combined Yampa-White river basin. Statewide reservoir storage is currently 82 percent of average. While reservoir storage is currently lowest in southern Colorado, it is encouraging that these basins did receive notable snow accumulation during recent storms.
In addition to the current snowpack and fall precipitation, one major consideration this year is that winter started with notable drought conditions across the state. The summer and fall of 2020 were abnormally hot and dry leaving soils in both the mountains and valleys of Colorado very dry. Wetlaufer continued to note that “With extremely dry soils existing under the snowpack, it is anticipated that soil moisture deficits will have to be satisfied by snowmelt, leaving less water available to make it to rivers and streams. This will lead to lower total streamflow amounts than would be commonly seen with a similar snowpack, regardless of what that ends up being”.
The average streamflow forecasts in different river basins range from 55 percent of average in the combined Yampa-White river basin to a high of 80 percent in the Upper Rio Grande river basin. Given the statewide drought conditions across Colorado going into winter, it will be a challenging year to determine exactly how to forecast the relationship between snowpack and streamflow. These relationships can also remain dynamic throughout the snowmelt season and on into the summer depending on future weather. Going forward, it will be important to keep an eye on changing conditions over the coming months.