The information gathered from December through March is critical to mountainous states such as Colorado that are generally dry and rely on snowfall for their water.

"Colorado provides water for a whole lot of states," said Larry Mahrt, a professor from Oregon State University who is leading the study.

"By using information about the snowpack in the mountains and upper river basins, you can assess soil measurements to try to predict conditions for activities such as farming," Mahrt said.

Reservoir operators also will use the information in deciding whether it's a year to draw down water supplies or to hold the line.

Joining Oregon State are scientists from the National Center for Atmospheric Research in Boulder and Colorado State University and the U.S. Forest Service in Fort Collins.

In late November, an array of high-tech instruments was planted on the former Case Ranch, about 5 miles south of Walden. Some of the instruments are mounted on a 78-foot-high tower, so measurements of wind, air temperature and humidity can be captured every 15 feet in altitude.

Along the ground is a forest of shorter poles with similar devices plus others to keep track of snow depths, soil temperatures and even how much sunshine is bestowed on the square-mile site.

The instruments and tower will be taken down in the spring.

Mahrt said scientists hope to improve computer models by better understanding atmospheric circulation, which is affected by the flux of heat, moisture and carbon dioxide from the snow surface.

Another goal is to look at differences in how the snow is distributed on the surface. The site was chosen because snowfall varies widely.

Mahrt described the 8,100-foot-high site as "rolly, with vegetation that ranges from dry sage to fairly thick grass in the bottomlands."

"Our job is to provide "ground truth' for the half-dozen satellites that take measurements from high overhead," Mahrt said. "The satellite operators can use what we find to calibrate their computer programs."

The computer models often don't jibe with snow measurements when snow is patchy or evaporates.

"If the data show that we are missing an important measurement, we will relocate sensors to fill in the gaps," said Steven Oncley, the NCAR scientist in charge of the project's instruments.

Mahrt said there will be intensive periods when the scientists are on scene monitoring the instruments all day, and there will be times when the instruments are checked about every two weeks.

During the long days, the scientists can huddle in a trailer at the site. "But most of the time, since we'll be outside, we'll be wearing eight layers of clothes," Mahrt said.