Multi-Radar Multi-Sensor (MRMS) QPE Products Update—2016/2017

The Multi-Radar Multi-Sensor (MRMS) system implemented at the National Centers for Environmental Prediction Central Operations has provided a group of quantitative precipitation estimation (QPE) products to users since the fall of 2014, which include a radar-based QPE, a radar QPE with local gauge bias correction and a gauge and precipitation climatology merged QPE (i.e., Mountain Mapper). The radar-based QPE suite has the highest spatial (~ 1 km) and temporal (2 min) resolution, least latency (< 5 min) and includes an instantaneous rate and 1- to 72h accumulations. The local gauge corrected radar QPE and Mountain Mapper suites include 1- to 72h accumulations that updates every hour and has a latency of ~ 1h. The precipitation rate fields have been used in national flash flood forecasts and the hourly accumulations from the radar-based and the local gauge bias corrected radar QPEs have been used in the National Weather Service River Forecast Centers for hydrological predictions and also as a forcing to the National Water Model.

During 2016/2017, several updates are made to the MRMS QPE products. The radar-based QPE is upgraded from using multiple radar reflectivity (Z) and precipitation rate (R) relationships to using a dual-polarization (DP) synthetic scheme based on Z, specific attenuation (A), and specific differential phase (K_DP). The DP synthetic QPE will provide improvements over the current radar QPE in heavy rain events during warm season. An evaporation correction is developed to mitigate radar QPE overestimation of light rain in areas of dry atmospheric environment. The local gauge corrected radar QPE is merged with Mountain Mapper to create a multi-sensor QPE, which will provide an unified product with better qualities across CONUS. In addition to the new QPE products, a update to the Canadian radar data quality control will largely reduce ground clutter contamination from anomalous propagation and improve the MRMS radar QPE quality in the high latitudes. The number of hourly gauge observations in MRMS will increase from ~8,000 to ~18,000 when the gauge input is switched from the current Hydrometeorological Automated Data System to the new Meteorological Assimilation Data Ingest System. This paper will provide an overview of the MRMS QPE updates and their impacts.