Spring and summer conditions are emerging slowly in Colorado’s high country. Highlighting one snapshot of these conditions, mountain snowpack monitoring stations across Colorado observed an average increase of 1.4 inches of snow water equivalent, equal to about one foot or more of snow depth, from one storm system during May 20th through the 24th.
Spring storms such as these are generally normal and often occur twice during the snowmelt season, but usually come earlier in the spring. As of June 1, statewide snowpack is significantly greater than normal. The last time statewide snowpack was this high was in 2011 when conditions were much the same as this year. However when focusing in on the basin scale, most individual basins’ current snowpack most closely compares with 1995, particularly in the southern and western basins. In 1995 snowpack peaked higher compared to this year. This year snowpack peaked at 134% of statewide normal.
“May was a particularly wet month, the second wettest month of the year at 174% of normal statewide. This coupled with the cool temperatures have aided mountain snowpack to persist later than normal,” said Brian Domonkos, Colorado Snow Survey supervisor.
In fact, this spring has exhibited one of the slowest snowmelt rates in many years. With May’s above-normal statewide precipitation, the year-to-date totals are now 124 %of average. The combined Yampa, White & North Platte maintains the lowest percent of average in the state at 116. Reservoir storage remains generally low in anticipation of rising streamflows as rivers have yet to peak.
“Below-normal reservoir levels will help in absorbing above-normal streamflows,” said Domonkos.
Since the snowpack peak in early to mid-April, snowpack is nearly half-melted according to SNOw TELemetery (SNOTEL) snowpack monitoring stations. With half of the snowpack remaining to melt, streamflows will rise as temperatures continue to warm.
This year’s snowpack is particularly high compared to last year and normal conditions, which are both relatively small. This disparity explains the relatively high percent of last year’s snowpack numbers such as in the Colorado, South Platte and statewide snowpack values.