If there is one common weakness among television weather forecasters, it may be their propensity to "overforecast" changes in the weather, according to UC Davis atmospheric science students who recently tracked the accuracy of five Sacramento-area television weather broadcasters. "Most broadcasters were expecting changes in the weather to be greater than they actually were," says Richard Grotjahn, a UC Davis professor of atmospheric science, who directed the study. Students in his weather analysis and prediction class recorded the late evening forecasts for the next day's high temperature, the three-day high and low forecasts and five-day high and low forecasts. They compared those predictions to the temperatures actually recorded by the National Weather Service 17 times over an eight-week period. While the final scores showed some forecasters doing better than others, the main purpose of the exercise was to help students understand better the science of weather forecasting. "The students realized that forecasting skill varies from day to day and even the worst forecaster can be the best on a given day," says Grotjahn. "But the best forecasters are those who minimize their forecasting busts." He added that the comparison showed that averaging the forecasts made by all of the weather broadcasters tended to show better results in the long-run than any individual forecaster.