GribStream

Rapid Refresh Forecast System Ensemble (RRFS Ensemble)

GribStream code: refsprslev

Description

The RRFS Ensemble is the experimental probabilistic extension of NOAA's next-generation Rapid Refresh Forecast System. This high-resolution (3 km), convection-allowing ensemble provides five members (m001-m005) every hour, enabling storm-scale ensemble prediction for North America. Unlike deterministic models, the RRFS ensemble provides a spread of outcomes, supporting probabilistic weather and risk guidance.

The deterministic/control RRFS forecast is available separately using the rrfsprslev code.

Each cycle assimilates dense observations—including radar, satellite, and surface—via hybrid 3D/4D-EnVar data assimilation, then launches five parallel forecasts (ensemble members) to represent forecast uncertainty. This system is designed for advanced nowcasting, severe weather risk assessment, ML/AI training, and research into convective predictability at the kilometer scale.

Key innovations

Detail

Technical details

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