Precipitation Frequency Analysis over Complex Terrain Using the High-Resolution Rapid Refresh

A multi-agency effort is underway to improve estimation of probable maximum precipitation (PMP) amounts over Colorado and New Mexico, and aid structural engineers in planning and assessment of dam safety. As part of this work, NOAA/ESRL is leveraging a 5-year (and growing) climatology of High-Resolution Rapid Refresh (HRRR) model forecasts, produced in real-time by GSD at 3-km resolution and hourly frequency, to quantify the climatological frequency of heavy and extreme precipitation events over regions that are poorly sampled in space and time by existing observational networks. The study region spans an elevation range of more than 3500 m, including regions where point precipitation observations are daily and sparse, and the beam of the nearest NWS WSR-88D radar is centered up to 5 km above the ground. Thus there exists potential to improve on existing PMP datasets by combining long-term observations with a shorter but more comprehensive record of forecasts from a numerical weather prediction model. This presentation will 1) describe the unique HRRR forecast dataset, 2) present initial results of a precipitation frequency analysis over the study domain, 3) identify mitigation strategies for issues such as a short period of record and dynamic model configuration, and 4) propose techniques for combining model forecasts with existing observation datasets to obtain an improved extreme precipitation climatology over the study region.