An Evaluation of Simulated Precipitation Characteristics During OLYMPEX

AbstractThe OLYMPEX field campaign, which took place around the Olympic Mountains of Washington State during winter 2015-2016, provided data for evaluating the simulated microphysics and precipitation over and near that barrier. Using OLYMPEX observations, this paper assesses precipitation and associated microphysics in the WRF-ARW model over the U.S. Pacific Northwest. Model precipitation from the University of Washington real-time WRF forecast system during the OLYMPEX field program (November 2015 to February 2016) and an extended period (2008-2018) showed persistent underprediction of precipitation, reaching 100 mm yr−1 over the windward side of the coastal terrain. Increasing horizontal resolution does not substantially reduce this underprediction.Evaluating surface disdrometer observations during the 2015-2016 OLYMPEX winter, it was found that the operational University of Washington WRF modeling system using Thompson microphysics poorly simulated the rain drop size distribution over a windward coast...