Figure 2:  New model simulations suggest that seasonal mean fluctuations in the climate of North American regions may be predictable during some seasons, especially during El Niño years. The bottom panel shows a 3-month retrospective forecast for the winter of 198889, made with a more recent improved climate model assuming that we know global sea-surface temperatures. The model forecasted quite accurately the large-scale shift in the structure of the atmospheric circulation that developed as a result of departures of ocean surface temperatures from their normal conditions. The top panel shows results from a model of 10 years ago, which did not show skill in forecasting this seasonal climate fluctuation. An improved ability to predict the upper atmospheric structure would allow forecasters to adjust their predictions of the track of the jet stream, thus improving predictions of whether winters in particular regions would be warmer or colder, and wetter or drier, than usual (see Appendix D for further information). Source: Center for Ocean-Land-Atmosphere Studies, Calverton, MD.


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