Quantitative precipitation forecasting of wintertime storms in the Sierra Nevada: Sensitivity to the microphysical parameterization

In this study, Quantitative Precipitation Forecasting (QPF) skill of PSU/NCAR Mesoscale Model MM5 was examined for the wintertime storms documented during the SCPP experiment in the 1980's, and the sensitivity of that skill to the choice of microphysical parameterization and horizontal resolution. The results show a tendency of existing microphysical schemes in MM5 to produce over-prediction of precipitation on both windward and lee slopes of the Sierra Nevada. The QPF skill is not simply improved by increasing the horizontal resolution. The QPF skill is on average better on the windward than on the lee side of the Sierra Nevada. Testing the statistical significance of the differences in the skill scores for different schemes shows that the differences are not statistically significant. Based on the skill scores and accuracy measures, the scheme developed by Reisner performed better than other schemes on both sides of the mountain range.