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North American Mesoscale Forecast System (NAM)

An animated image of NAM total surface 3-hourly precipitation, forecast from 03UTC on July 10, 2012 to July 13, 2012 at 12UTC. In the initial few frames, hurricane Emilia can be seen in the bottom left corner spinning off to the west. This image was produced with the Grid Analysis and Display System (GrADS) and ImageMagick.

The North American Mesoscale Forecast System (NAM) is one of the major weather models run by the National Centers for Environmental Prediction (NCEP) for producing weather forecasts. Dozens of weather parameters are available from the NAM grids, from temperature and precipitation to lightning and turbulent kinetic energy. The NAM generates multiple grids (or domains) of weather forecasts over the North American continent at various horizontal resolutions. High-resolution forecasts are generated within the NAM using additional numerical weather models. These high-resolution forecast windows are generated over fixed regions and are occasionally run to follow significant weather events, like hurricanes. The NAM homepage is an excellent source of information for how the model is configured and run, and an excellent source of forecast products. The Continental United States (CONUS), 12km resolution, gridded data are available for download through NOMADS.

A plot of NAM data showing an analysis of mean sea-level pressure on July 10, 2012 at 00UTC. Low pressures are colored in red, higher pressures in blue. In the bottom left corner, the center of hurricane Emilia (a category 2 hurricane at this time) is visible as a red dot surrounded by an orange circle. Data contours were generated with the Grid Analysis and Display System (GrADS) and visualized with Quantum GIS (QGIS), an open-source Geographic Information System (GIS).