A Real-Time Precipitation Monitoring Algorithm—Quantitative Precipitation Estimation and Segregation Using Multiple Sensors (QPE SUMS)

Numerous studies have documented the low reliability of operational Precipitation Processing System products especially for cool season, stratiform precipitation in complex terrain. Collaboration between Arizona NWS forecasters and researchers at the Salt River Project and National Severe Storms Laboratory has led to the implementation of an improved and more robust real-time QPE scheme. In its current configuration, QPE SUMS produces accumulations every 5 minutes on a grid covering the entire sate of Arizona. The grid cell resolution is approximately 1x1 km. Beginning with full volume, level II data from 4 WSR-88D radars, it eliminates reflectivity from non-weather targets (e.g., ground clutter and AP), identifies convective and stratiform echo, utilizes appropriate Z-R equations, and mosaics accumulations from adjacent radars. If a bright band is detected, then a multi-sensor QPE approach is applied. In "cool season mode", QPE SUMS uses radar-observed melting layer heights to differentiate between frozen and liquid precipitation. Additionally, IR satellite data are adaptively calibrated by radar precipitation rates sampled below the melting layer in order to provide more reasonable QPEs to regions where radar samples within and above the bright band. An algorithm overview will be presented as well as results from selected winter extratropical cyclones and summer convective storms affecting Arizona.