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Joseph P. Zagrodnik, Lynn McMurdie, and Robert Conrick

with synoptic observations, although the model is prone to underpredicting cloud water and overpredicting snow mixing ratios ( Conrick and Mass 2019a ; Conrick and Mass 2019b ). Figure 1 shows the 36–12–4–1.33-km model domain configuration with 51 vertical levels. The innermost 1.33-km domain is centered over the Olympic Peninsula. Model initialization and boundary conditions were driven by the 0.25° Global Forecast System (GFS) gridded dataset. The 36-km grid boundaries were nudged every 3 h

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Robert Conrick, Clifford F. Mass, and Qi Zhong

–12–4–1.33–0.444 km domain configuration is applied with 51 vertical levels, 1 with the innermost domains centered over the Olympic Peninsula of Washington State ( Fig. 1 ). Initial and 3-h boundary conditions are from the NOAA/National Weather Service Global Forecast System (GFS) 0.25° gridded analysis. Since new GFS data are available every 6 h, only forecast hours 0000 and 0300 are used for boundary conditions and nudging. Fig . 1. Map of the WRF-ARW domains used in this study. The outer domain has 36-km grid

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Minda Le and V. Chandrasekar

Polarimetric Radar (NPOL), and CSU–CHILL radar in the last three years of 2014–18. Fourteen validation cases are selected under different geographical conditions, different seasons of the year, and different surface types. For those cases occurred during the OLYMPEX campaign, we enhanced the validation results ( Chandrasekar and Le 2017 ) together with site ground reports and Precipitation Imaging Package (PIP) images. A match ratio is calculated between surface snowfall product and ground radar retrievals

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Robert Conrick and Clifford F. Mass

conditions. Some surface parameters were initialized from other sources. 2 Model parameterization choices included the Noah LSM with multiparameterization options (Noah-MP; Niu et al. 2011 ), the Rapid Radiative Transfer Model for GCMs (RRTMG) radiation scheme ( Iacono et al. 2008 ), and the Yonsei University (YSU; Hong et al. 2006 ) boundary/surface-layer scheme. A cumulus parameterization scheme (Grell–Freitas; Grell and Freitas 2014 ) was used in all but the 1.33-km domain. Only forecasts from the

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Hannah C. Barnes, Joseph P. Zagrodnik, Lynn A. McMurdie, Angela K. Rowe, and Robert A. Houze Jr.

gradient and a 180° wind shift at 925 hPa ( Fig. 3b ). Data presented in Figs. 4a and 5a suggest that a strong low-level stable frontal inversion of over 8°C and strong directional shear below 1 km resulted in conditions that could support the development and maintenance of KH waves because the Ri was less than 0.25 in multiple layers below 1 km near Davenport. The radar-observed KH waves were located near Waterloo, which is approximately 180 km to the northwest. Given that the frontal boundary

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David J. Purnell and Daniel J. Kirshbaum

representation of upstream thermodynamic and wind profiles, and (iii) uncertainties in model subgrid parameterizations, such as cloud microphysics and boundary layer turbulence. Because of these limitations, retrievals using denser gauge networks and more sophisticated algorithms, analyses of a larger collection of observed events (including occluded fronts), and ensembles of more realistic simulations that consider uncertainties in physical parameterizations and initial conditions are recommended for future

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Aaron R. Naeger, Brian A. Colle, Na Zhou, and Andrew Molthan

configuration focused on the OLYMPEX field site (i.e., Fig. 1c ). Vertical grid spacing increased from about 60 m near the surface to 240 m at 2 km in height. Forecasts were initialized at 1200 UTC 12 November 2015 with initial and lateral boundary conditions provided by the 6-h Global Forecast System (GFS) reanalysis data at 0.25° grid spacing. Other atmospheric analysis data, including the 20-km Rapid Update Cycle, led to unrepresentative meteorological conditions and poorer agreement between the

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Annareli Morales, Hugh Morrison, and Derek J. Posselt

horizontal grid spacing is 2 km for the inner domain (1200 km in length) and stretches up to 6 km over 50 grid points on either side. The domain is 1600 km in length, and the total depth is 18 km with 55 vertical levels. The vertical grid spacing is 0.25 km from the surface to a height of 9 km, increases to 0.5 km between 9 and 10.5 km, and then remains constant at 0.5 km until 18 km. Lateral boundary conditions are open radiative, with a no-slip bottom boundary condition and free-slip top boundary

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Robert Conrick and Clifford F. Mass

. Initialization and boundary conditions were driven by the 0.5° NOAA/National Weather Service (NWS) Global Forecast System (GFS) gridded forecasts, with some surface parameters initialized from other sources. 1 Boundaries were updated and the 36-km grid nudged every 3 h using the GFS forecasts. Parameterization options included the Noah-MP land surface model ( Niu et al. 2011 ), the RRTMG radiation scheme ( Iacono et al. 2008 ), the Yonsei University (YSU; Hong et al. 2006 ) boundary/surface layer (PBL

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Zeinab Takbiri, Ardeshir Ebtehaj, Efi Foufoula-Georgiou, Pierre-Emmanuel Kirstetter, and F. Joseph Turk

Johnson 2011 ). These characteristics are difficult to accurately parameterize as of today. Second, the already weak snowfall scattering signal tends to be masked by the increased atmospheric emissivity and liquid water content in precipitating conditions ( Liu and Seo 2013 ; Wang et al. 2013 ; Panegrossi et al. 2017 ). Third, changes in surface emissivity due to snow accumulation on the ground can significantly alter the snowfall microwave signal. Dry snow cover scatters the upwelling surface

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