Snow in Colorado

Snow occurs in all areas of Colorado in varying amounts. Snow falls in some part of the state during every month of the year.

Density

The average density of freshly fallen snow in Colorado is 7%.

This means that 10 inches of snow equals 0.7 inches of water or 14 inches of snow equals 1 inch of water.

Over time, the snow becomes more compacted. By the time snow begins melting, it usually has a density of 30-40%.

This means that 3-4 inches of snow equals 1 inch of water.

Influence on water supply

Snowpack provides approximately 75% of Colorado's streamflow and therefore a large portion of the water supply. It is important to keep the following ideas in mind when thinking about Colorado's water supply and demand:

Supply occurs mostly in the winter.

Demand occurs mostly in the summer.

Supply occurs mostly in high places.

Demand occurs mostly in low places.

Snow Courses and SNO-TEL Sites

Snow courses are operated by the Natural Resources Conservation Service (formerly the Soil Conservation Service). Measurements taken at snow courses are used to predict how much runoff will occur in the spring. This information is used by cities, farmers and recreationalists for planning purposes.

A snow course is a permanently marked data site where manual snow measurements are collected on the first day of each month from January through June.

There are approximately 150 snow courses in Colorado.

When a measurement is made at a snow course, the depth of the snow and the density of the snow are measured. These values, measured at numerous locations, are used to estimate the amount of spring runoff that will occur.

SNO-TEL is an abbreviation for SNOw-TELemetry. SNO-TEL sites are used in the western United States for obtaining snow water equivalent, precipitation, air temperature, and other hydrologic measurements from remote data sites via radio transmission.: There are approximately 75 SNO-TEL sites in Colorado.

A picture of a snow pillow near Berthoud Pass.

The Natural Resources Conservation Service makes SNO-TEL data available to the public.

Avalanches can frequently present a hazard in the high country.

Sources:

Doesken, Nolan J. Assistant State Climatologist.

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