CHANGES TO THE 1995 NCEP OPERATIONAL MEDIUM-RANGE FORECAST MODEL ANALYSIS-FORECAST SYSTEM

Recent changes in the operational National Centers for Environmental P rediction (formerly the National Meteorological Center) global analysi s-forecast system are described. The most significant analysis change was the direct use of satellite-measured radiances as input to the ana lysis 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 sy stem produced substantially better forecasts of geopotential height an d wind throughout the troposphere, especially in the Southern Hemisphe re. Precipitation forecasts over the United States were slightly more skillful in the new system. Subjective evaluations over the Tropics re vealed that the new model is more active at smalt scales, producing mo re clearly defined convective rain cores and vorticity patterns.