Rapid Refresh Forecast System (RRFS)

GribStream code: rrfsprslev

Description

The Rapid Refresh Forecast System (RRFS) is NOAA's next-generation, convection-allowing numerical weather prediction system. It is built on the FV3 dynamical core within the Unified Forecast System (UFS) and is intended to replace the HRRR and RAP models. RRFS runs at approximately 3 km horizontal resolution over North America, allowing explicit simulation of convective storms instead of relying on coarse convective parameterizations.

High-resolution, storm-scale guidance is critical for severe weather nowcasting, renewable energy forecasting, aviation routing, transportation logistics, and emergency management. RRFS assimilates a dense set of observations every hour (radar reflectivity/velocity, satellite, aircraft, surface mesonets) using advanced hybrid 3D/4D-EnVar data assimilation techniques. The result is more frequent, higher-fidelity forecasts of thunderstorms, precipitation bands, wind gusts, ceiling/visibility, and other mesoscale phenomena.

Key innovations

• FV3-based nonhydrostatic dynamical core with improved numerics.
• Unified Forecast System (UFS) architecture for simpler maintenance and upgrades.
• Hybrid ensemble-variational data assimilation with frequent radar ingest.
• Single seamless 3 km NA domain (replacing separate HRRR/RAP footprints).

Detail

• Experimental: RRFS is still experimental. Output formats, fields, and cadence can change without notice.
• Archive window: Only the last 15 days are currently available. Once RRFS is fully productionalized (targeted for 2026), GribStream will backfill the history further back for a continuous long-term archive.
• Continuity: The feed may be paused or discontinued at any time.

Technical details

• Resolution: ~3 km horizontal (convection-allowing).
• Cadence: Hourly analysis/forecast cycles.
• Forecast length: Up to 84 hours per cycle.

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