While lower altitudes in Colorado slowly moved from spring toward summer, the high country was still holding onto winter through May, receiving about a foot of snow from one storm system between May 20 and 24, the Natural Resources Conservation Service reported.
While spring storms such as the one in May are common, they usually come much earlier in the season and fall on mountains that have already begun melting their winter snowpack.
As of June 1, the statewide snowpack was at 511 percent of normal. The last time the snowpack was that high was in 2011, when conditions were about the same as 2019.
“May was a particularly wet month, the second wettest month of the year, at 174 percent of normal statewide,” said Brian Domonkos, Colorado Snow Survey supervisor. “This, coupled with the cool temperatures, has aided mountain snowpack to persist later than normal. In fact, this spring has exhibited one of the slowest snowmelt rates in many years. Below-normal reservoir levels will help in absorbing above-normal steamflows.”
Snowpack in the Arkansas River Basin is 439 percent above normal, with May precipitation at 168 percent of average. That brings the water year-to-date precipitation to 119 percent of average.
Reservoir storage for the basin at the end of May was 86 percent of average, compared to 127 percent last year.
Streamflow forecasts for the Arkansas River at Salida for June through July are at 170 percent.
Because of the above-average May precipitation and high snowpack, most state rivers are expected to see above-average streamflows.
Flow rates in the northern half of the state are expected to be lower, relative to the southern half, but still at or above average volumes, the NRCS reported. Western and southern Colorado are expected to be in the range of 130 to 150 percent of average seasonal streamflows.