The NCEP North American Mesoscale Modeling System : Recent changes and future plans

In June 2006 NCEP implemented into the North America Mesoscale (NAM) Modeling System the WRF version of the Non-Hydrostatic Mesoscale Model (WRF-NMM), and a regional version of the NCEP Grid-Point Statistical Interpolation (GSI) analysis, replacing the Eta model and the Eta 3D-VAR analysis. Since this initial implementation, several significant upgrades to the NAM have been performed, including changes to the WRF-NMM dynamics and physics (including gravity-wave drag/mountain blocking, and unified (with NCAR) land-surface physics), assimilation of new observation types (METOP, AIRS and GOES 1x1 radiances, TAMDAR/AMDAR aircraft data), and changes to the NAM Data Assimilation System (NDAS). Further details on these changes and their impact on NAM forecast performance will be presented.

By late 2010, the NAM will be changed to run within new ESMF-based NCEP Environmental Modeling System (NEMS) framework. In addition to the current 12 km North American run, NCEP plans to add a CONUS and Alaska 5 km nested run inside the 12 km parent run. An overview of the planned changes will be presented.