Summit County Citizens Voice

Spring storms continue to beef up the snowpack in the northern Rockies.

Big snowpack in northern Rockies, intensifying drought in Southwest

By Summit Voice

SUMMIT COUNTY — It’s the season for western water managers to keep a close eye on the snowpack and projected runoff, and the story in the early spring is the same as it was all winter long — well above average snowfall in the northern sector, with intensifying drought in big parts of the Southwest.

According to the Western Water Assessment, snowfall was significantly above the long-term norms in the northern Colorado mountains, the Wasatch Front in Utah and northern and western Wyoming, while little precipitation fell across central Wyoming, eastern and southern Utah and the plains of Colorado.

Snowpack values in the three-state Intermountain West region (Colorado, Utah, Wyoming) stayed on the same trajectory as all winter, with most basins reporting above-average water content. Southern Colorado was the exception, where snowpack has been lagging near or below average for most of the fall and winter.

NRCS outlook for natural streamflows for spring and summer 2011 in the Intermountain West region as a percent of average streamflows (data through April 1, 2011). (Source: NRCS)

Critical April 1 snowpack readings were above average in all of Wyoming’s river basins, with the statewide average at 123 percent of normal. Utah’s tally is even higher, with a statewide snowpack moisture content at 135 percent of average, the highest since 1983. Both the Weber and Ogden basins reported their highest-ever April 1 snowpack readings since automated measuring began 40 years ago.

In Colorado, the northern river basins reported well above-average snowpack readings as of April 1, but the southern basins were below average, bringing the statewide reading to 113 percent of average.

In an April 12 update, the Colorado dust-on-snow program reported five dust events to-date, all since mid-February. Such events become more common after April 20, so there may be more dust storms on the way, but thus far, the total dust loading in a test area in the San Juans is lower than in 2010.

Overall, April to July inflow into Lake Powell, the reservoir in the greater Colorado River Basin, is expected to be about 120 percent of average.

Good news for Lake Powell in this graph.

In Colorado, runoff in northern river basins like the Yampa and North Platte could be as high as 14 percent of average. Higher than average runoff is also expected in the Gunnison Basin, while the South Platte and Arkansas basins are expected to run near average.

Filed under: climate and weather, Colorado, Environment, La Niña, rivers, Snow and weather, water Tagged: | Colorado, Intermountain West, Lake Powell, snowpack, spring runoff, Summit County Colorado, Summit County News, Utah, Wasatch Front, West