Changes to the 1995 NCEP operational medium-range forecast model analysis-forecast system

Recent changes in the operational National Centers for Environmental Prediction (formerly the National Meteorological Center) global analysis-forecast system are described. The most significant analysis change was the direct use of satellite-measured radiances as input to the analysis system. Other analysis system changes involved the inclusion of near-surface winds from the ERS-1 satellite system and the addition of a constraint on the divergence increment. In the forecast model, the parameterization of deep convection and the boundary layer scheme were modified. During two months of tests (June and July 1995), the new system produced substantially better forecasts of geopotential height and wind throughout the troposphere, especially in the Southern Hemisphere. Precipitation forecasts over the United States were slightly more skillful in the new system. Subjective evaluations over the Tropics revealed that the new model is more active at smalt scales, producing more clearly defined convective rain cores and vorticity patterns.