With one of the largest snowpacks on record in the Sierra and average to above-average amounts of snow in the Wasatch Range and Northern Rockies, scientists with the U.S. Geological Survey are gearing up for a busy June, when much of that snow will turn to water; perhaps too much in too short a time.

One of those scientists, Dr. David Peterson, has helped to develop computer models that forecast, with reasonable accuracy, the amount of snow that will melt in a certain place, over a given time period, under certain conditions. Peterson will describe these models at the spring meeting of the American Geophysical Union, May 28, in Boston, Mass.

Air temperature is the key factor in the statistical model, according to Peterson, and with the model that he and others have developed, the effect of sudden and sustained temperatures changes can be modeled to predict discharge, or runoff in individual stream basins.

With fresh snow falling as late as May 20 in the California Sierra and air temperatures generally remaining below 60 degrees, this year's runoff will begin later than usual.

As the nation's largest water, earth and biological science, and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation and the economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources.