Improved Model Output Statistics Forecasts through Model Consensus

Abstract

Consensus forecasts are computed by averaging model output statistics (MOS) forecasts based on the limited-area fine-mesh (LFM) model and the nested grid model (NGM) for the three-year period 1990?92. The test consists of four weather elements (max/min temperature, wind speed, probability of cloud amount, and 12-h probability of precipitation) at four projection times from each initialization (0000 and 1200 UTC) for roughly 250-350 stations. Verification results clearly indicate a substantial improvement for the consensus MOS over both the LFM and NGM MOS forecasts for all variables and all lead times. The accuracy increase is on par with a 2-8-yr scientific advancement and a 4-12-h lead time improvement. Moreover, performance of the consensus MOS forecasts is similar to subjective forecasts issued by the National Weather Service. These results are illustrative of the broad need to adopt a strategy of statistically combining available forecast products rather than relying upon the single most superior product (such as the newest numerical model). Furthermore, there appears to be strong justification to continue support for the entire LFM MOS product both in terms of its full availability and its equation upgrade.