NOAA’s Rapid Refresh Forecast System (RRFS) became operational on November 3, replacing five regional forecasting services as the National Weather Service modernizes its short-range guidance. The system brings hourly-updating forecasts across North America and extends forecast lead time for the contiguous United States to 84 hours, according to NOAA.

What changed with RRFS

The implementation retires the North American Mesoscale (NAM), Short-Range Ensemble Forecast (SREF), High-Resolution Ensemble Forecast (HREF), High-Resolution Window (HiresW) and NAM Model Output Statistics (MOS). NWS service notices set the change for November 3; NOAA says RRFS and its ensemble companion, REFS, take over the regional guidance role.

NOAA describes RRFS as combining features of earlier systems: frequent updates associated with HRRR and a broader area similar to NAM. Its 3-kilometer grid is designed to resolve local-scale weather patterns, while the contiguous-U.S. forecast extends to 84 hours, compared with 48 hours for HRRR. NSF Unidata, which distributes operational model output to research and forecasting users, confirms RRFS and REFS data are now available and that the retired NAM, SREF, HREF and HiresW systems have been decommissioned.

What it means for forecasts

The change gives forecasters and downstream data users a consolidated source of short-range model guidance instead of several separate regional systems. It does not mean every forecast will be more accurate in every situation: forecast performance still depends on the weather pattern, observations and how forecasters interpret model output. NOAA says the RRFS suite also includes tools for smoke and dust prediction and an on-demand finer-resolution mode for selected high-impact conditions.

For the public, the transition is mostly behind the scenes. Local forecasts and warnings continue through the National Weather Service; RRFS is one of the models that can inform that guidance. Researchers and technical users can access the new output through NSF Unidata’s data services.

Sources: NOAA’s RRFS implementation release; National Weather Service Service Change Notice 26-47; NSF Unidata on RRFS and REFS data availability.