The RUA is designed for a 10-min latency, quickly available. An initial prototype RUA has already been developed at NOAA/ESRL and is running at 1-h frequency using a 1-h HRRR forecast background field and is available 60-75 min after the hour. The RUA analysis differs from an analysis used to initialize a model (such as the HRRR) by fitting the observations more closely (after careful observation quality control). This close fit applies to both in situ observations (especially surface observations), but also remotely sensed observations, such as radar data and satellite-derived cloud information. While highly desirable for RTMA/RUA applications, this close fit to observations has the potential to degrade model forecasts. As examples, specification of complete 3D hydrometeor fields from radar data can result in excessive short-range precipitation, leading to a high bias in the soil moisture and related problems. Similarly, full specification of saturated clouds throughout the atmosphere, can lead to a high relative humidity bias. Because the RUA uses a cycled model background, it benefits from the ability of the model to propagate information from observation-rich regions to observation-sparse regions. An example of this benefit is the analysis of precipitation hydrometeor fields (from the background) in regions that do not have radar reflectivity coverage.
Planned work is to move the RUA to a 15-min update interval sand increase the update frequency of the underlying HRRR-system, as well as improving the horizontal resolution, and adding more observations to the assimilation. Further work will focus on improving the error covariance information, adding more output fields, and examining nowcast capabilities using the RUA fields as initial conditions. With these enhancements, the RUA has the potential to unify many existing NOAA systems and provide highly accurate, consistent 3D guidance for users in many sectors, including short-range forecasting, aviation, severe-weather, and hydrology. At the conference, an overview of the system and update on ongoing work will be presented.