The Development of an Urban Rain Rate Dashboard (URRD) at the NOAA Weather Prediction Center

Flooding is the most common, costly, and deadly weather-related disaster in the United States (Alliance 2020). Urban flooding is a category of flooding that occurs when precipitation exceeds the capacity of the urban watershed to infiltrate the water into the ground or the drainage system to carry it away (Galloway et al. 2018). A large and increasing number of people are impacted annually by urban flooding (National Academies 2019). This increase can be attributed to a number of factors including population growth within cities, expansion of the impervious surfaces that feed aged or outgrown stormwater infrastructure, local development policies, and climate change (National Academies 2019; Galloway et al. 2018). The precipitation responsible for urban flooding is typically intense, convective rainfall of relatively short duration; however, large-scale weather systems of tropical and extratropical origin can also result in urban flooding.

The NOAA/NWS/Weather Prediction Center (WPC) is developing the Urban Rain Rate Dashboard (URRD) to highlight the threat of urban flooding up to three days in advance. The dashboard will use primarily convective-resolving ensembles to depict urban areas in the United States under the threat of intense rainfall. Accumulated rainfall predictions as short as 15 minutes and as long as 12 hours are analyzed and compared to Average Recurrence Intervals (ARIs). The primary input to the URRD is whether or not ARIs are exceeded in a metropolitan area. The URRD is available as a website display of the nation’s largest cities vs time, depicting a threat level scaled by color (e.g., green, yellow, orange, red). Its purpose is to provide a big-picture decision support tool for the NWS and its partners in emergency and stormwater management. The URRD is driven only by ensemble data, and does not replace the interactive and real-time operational decision support services provided by the NWS National Centers and Weather Forecast Offices. Further development in the presentation of the information will be aided by the Nurture Nature Center (NNC), which conducted focus groups with several large US cities’ emergency and stormwater managers. The Rapid Ensemble Forecast System (REFS) and the Global Ensemble Forecast System (GEFS) have been used for prototyping the URRD and for the NNC focus groups evaluations. Plans are underway to utilize the HREF as well.

This presentation will describe the latest development of the URRD and show examples of its output. An update of the ensemble membership that drives the URRD will be provided. Preliminary URRD verification work will also be shown.