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Composite Reflectivity


The High-Resolution Rapid Refresh


The HRRR is a 3-km resolution, hourly updated, cloud-resolving atmospheric model, initialized by DFI-fields from the 13km radar-enhanced Rapid Update Cycle (RUC) run at NOAA/ESRL/GSD. (soon to be initialized similarly by the 13km radar-assimilating Rapid Refresh ).

    The HRRR uses
  • a configuration of the WRF model, similar to that used for the Rapid Refresh (ARW core, Thompson microphysics, etc., as defined here ), but without any convective parameterization.
  • initialized with latest 3-d radar reflectivity via 13km development RUC at GSD, which includes radar reflectivity assimilation via its radar-DFI (digital filter initialization) technique.
  • currently runs over a Northeast Corridor domain from Missouri-Minnesota on the western boundary to the Atlantic Ocean on the east boundary.
  • no separate data assimilation, relying instead on radar-assimilating RUC.
  • 1-way nest inside RUC (including cloud hydrometeors specified on lateral boundaries)
The HRRR is the only hourly updated, radar-initialized, storm-resolving model running at this time over the US (or internationally), to our best knowledge.
    As a higher-resolution nest inside the hourly-updated Rapid Refresh (and current RUC), the HRRR is designed to
  • provide rapidly updated model guidance on convective storms for
    • air traffic management
    • severe weather forecasting
    • NOAA National Weather Service Warn-On Forecast
  • eventually provide improved background fields for NWS Real-Time Mesoscale Analysis
  • provide improved basis for other aviation hazard forecasts (e.g., wake vortex, ceiling, visibility, turbulence, inflight icing, terminal forecasts)
  • The HRRR is fully dependent on the hourly-updated Rapid Refresh and currently, the radar-enhanced Rapid Update Cycle (RUC) , as shown in daily comparisons of 3km model runs with and without the 13km radar-reflectivity assimilation in the RUC/RR.