Skill In Forecasting Daily Temperature and Precipitation: Some Experimental Results
Abstract Estimates of skill in prediction of daily temperature and precipitation are obtained from a six-year record of real-time forecasts for Boston made in the Department of Meteorology at Massachusetts Institute of Technology. No secular increase of skill is found during the period 1966–1972, despite continuous improvement of predicted synoptic-scale flow patterns at the surface and at 500 mb, which were used for guidance. Skill, defined as incremental accuracy of the forecasts over forecasts of the climatological mean, is near 50% for the first day. The decrease of skill with increasing range is more rapid for precipitation than for temperature, the 10% level being reached in two and one-half days and four days, respectively. A pronounced seasonal variation of skill, with a summer minimum, is attributed to a similar variation in the importance of synoptic-scale, as opposed to mesoscale, sources of weather variability. The latter sources are seen as primarily responsible for the present limit of first...