Evaluating NOAA Climate Forecasting System Subseasonal Forecasts

This talk will describe a multi-year evaluation of the 1-5 week forecasts of the NOAA Climate Forecasting System (CFS) over the globe, North America, and the western U.S.   Forecasts are evaluated for both specific times and for a variety of time-averaging periods.  Initial results show a loss of predictability at approximately three weeks, with sea surface temperature retaining predictability longer than atmospheric variables.   It is demonstrated that a major CFS problem is an inability to realistically simulate propagating convection in the tropics, with substantial implications for midlatitude teleconnections and subseasonal predictability.  The inability of CFS to deal with tropical convection will be discussed in connection with the prediction of major circulation anomalies over the midlatitudes.