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Philip T. Bergmaier and Bart Geerts

eta ( η ) levels, the first 14 of which are in the lowest 1 km AGL. Initial and lateral boundary conditions were generated at 6-h intervals with analyses from the 12-km North American Mesoscale Forecast System (NAM). The simulation was run for 96 h, from 0000 UTC 6 January to 0000 UTC 10 January. The model physics configuration includes the Yonsei University planetary boundary layer scheme ( Hong et al. 2006 ), the revised MM5 surface layer scheme ( Jiménez et al. 2012 ), and the Noah land surface

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Seth Saslo and Steven J. Greybush

events by altering wind fields and creating local orographic lift ( Onton and Steenburgh 2001 ; Alcott and Steenburgh 2013 ). This can result in localized precipitation enhancement ( Veals and Steenburgh 2015 ), although the mechanisms associated with this are still under investigation ( Minder et al. 2015 ; Campbell et al. 2016 ). It follows that an accurate LES precipitation forecast needs to account for large-scale synoptic forcing, as well as local features and mesoscale variables. As a result

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David A. R. Kristovich, Richard D. Clark, Jeffrey Frame, Bart Geerts, Kevin R. Knupp, Karen A. Kosiba, Neil F. Laird, Nicholas D. Metz, Justin R. Minder, Todd D. Sikora, W. James Steenburgh, Scott M. Steiger, Joshua Wurman, and George S. Young

N. F. Laird , 2012 : Great Salt Lake–effect precipitation: Observed frequency, characteristics, and associated environmental factors . Wea. Forecasting , 27 , 954 – 971 , doi: 10.1175/WAF-D-12-00016.1 . 10.1175/WAF-D-12-00016.1 Ballentine , R. J. , A. J. Stamm , E. E. Chermack , G. P. Byrd , and D. Schleede , 1998 : Mesoscale model simulation of the 4–5 January 1995 lake-effect snowstorm . Wea. Forecasting , 13 , 893 – 920 , doi: 10.1175/1520-0434(1998)013<0893:MMSOTJ>2

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W. James Steenburgh and Leah S. Campbell

, and mixed forest (not shown). Analyses from the NCEP North American Mesoscale Forecast System (NAM) provide initial atmospheric and land surface (soil moisture, soil temperature, and snow cover) conditions at 1200 UTC 10 December 2013, as well as lateral boundary conditions at 6-h intervals throughout the study period. For Great Lakes surface temperatures, we use the Great Lakes Environmental Research Laboratory (GLERL) Great Lakes Coastal Forecasting System analysis at 6-h intervals. In areas

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David A. R. Kristovich, Luke Bard, Leslie Stoecker, and Bart Geerts

1. Introduction Forecasts of lake-effect snowstorms have become increasingly accurate as numerical atmospheric simulations have improved. However, critical details of the mesoscale structure, spatial and temporal distribution of snowfall, snowband movement, and precipitation intensity continue to be difficult to predict (e.g., Niziol et al. 1995 ). Much of the forecast difficulty is due to smaller-scale processes within the lake-effect boundary layer ( Saslo and Greybush 2017 ), many of which

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Daniel T. Eipper, George S. Young, Steven J. Greybush, Seth Saslo, Todd D. Sikora, and Richard D. Clark

://doi.org/10.1175/1520-0469(1989)046<1877:AAIOMC>2.0.CO;2 . 10.1175/1520-0469(1989)046<1877:AAIOMC>2.0.CO;2 Ballentine , R. J. , A. J. Stamm , E. E. Chermack , G. P. Byrd , and D. Schleede , 1998 : Mesoscale model simulation of the 4–5 January 1995 lake-effect snowstorm . Wea. Forecasting , 13 , 893 – 920 , https://doi.org/10.1175/1520-0434(1998)013<0893:MMSOTJ>2.0.CO;2 . 10.1175/1520-0434(1998)013<0893:MMSOTJ>2.0.CO;2 Banacos , P. C. , and M. L. Ekster , 2010 : The association of the

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Peter G. Veals and W. James Steenburgh

the Great Salt Lake of Utah. Synoptic, mesoscale, lake-surface, and land surface conditions influence the areal coverage, intensity, and organization of lake-effect precipitation systems, leading to a rich morphological spectrum that includes the following: Wind-parallel bands generated by land-breeze convergence when the prevailing flow is oriented along the long axis of an elongated body of water (e.g., Peace and Sykes 1966 ; Passarelli and Braham 1981 ; Braham 1983 ; Hjelmfelt 1990

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Leah S. Campbell, W. James Steenburgh, Peter G. Veals, Theodore W. Letcher, and Justin R. Minder

-00016.1 . Barnes , S. L. , F. Caracena , and A. Marroquin , 1996 : Extracting synoptic-scale diagnostic information from mesoscale models: The Eta model, gravity waves, and quasigeostrophic diagnostics . Bull. Amer. Meteor. Soc. , 77 , 519 – 528 , doi: 10.1175/1520-0477(1996)077<0519:ESSDIF>2.0.CO;2 . Benjamin , S. G. , and Coauthors , 2016 : A North American hourly assimilation and model forecast cycle: The Rapid Refresh . Mon. Wea. Rev. , doi: 10.1175/MWR-D-15-0242.1 , in press . Bergeron

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Daniel T. Eipper, Steven J. Greybush, George S. Young, Seth Saslo, Todd D. Sikora, and Richard D. Clark

environmental baroclinity in lake-effect settings and exploring the influences of both weak and strong environmental baroclinity on the inland structure of lake-effect snowbands. Lake-effect snowstorms are known to form in diverse modes or morphologies, including 1) multiple wind-parallel rolls (cloud streets; e.g., Sikora et al. 2001 ), 2) mesoscale vortices, and 3) one or sometimes two band(s) parallel to the major axis of an elongated body of water (e.g., Holroyd 1971 ; Kelly 1986 ; Hjelmfelt 1990

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Leah S. Campbell and W. James Steenburgh

). We used the U.S. Geological Survey (USGS) land-use dataset for land-use characteristics and the North American Mesoscale Forecast System (NAM) analyses for atmospheric initial and lateral boundary conditions (6-h intervals), land surface conditions, and snow-coverage distribution. Over the Great Lakes, we specified ice cover manually based on inspection of Great Lakes Environmental Research Laboratory (GLERL) ice-cover analyses from 11 and 12 December and included localized ice cover in Black Bay

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