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Thomas R. Parish and Richard D. Clark

show a decrease with height, representing the effects of the thermal wind induced by isobaric temperature gradients. Even during the nighttime hours, warmest air resides over the highest terrain. The seasonal time scale of heating contributes to the mean or background geostrophic wind, whereas the diurnal cycle serves to perturb the mean horizontal pressure gradient force. 4. Summary Development of the nocturnal wind maximum in the lower atmosphere over the Great Plains states has incited

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Thomas R. Parish

highly concentrated summertime flows over the Great Plains result from larger-scale inertial effects similar to those that drive the Gulf Stream. Wexler (1961) argued that the strength of the southerly flow east of the Rocky Mountains is a prerequisite to the nighttime LLJ development (see also Ting and Wang 2006 ). Lettau (1967) offered that the diurnal heating and cooling of the sloping terrain must be considered in any explanation of the LLJ. Sangster (1967) demonstrated that a diurnal

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Aaron Johnson, Xuguang Wang, Kevin R. Haghi, and David B. Parsons

1989 ; their Eqs. (2.4)–(2.6)]: Here, h 1 is the depth of the stable layer after bore passage, C is the bore speed, g ′ is reduced gravity, and u 1 is the bore-relative flow (different from the density current relative flow U ). It has been shown ( Klemp et al. 1997 ; Kingsmill and Crook 2003 ) that the following equation improves upon the derivation for C in Eq. (3) and Rottman and Simpson (1989) by including the effects of energy dissipation by undulations and turbulence and the

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Aaron Johnson and Xuguang Wang

-allowing and convection-parameterizing ensemble forecasts of a mesoscale convective vortex and associated severe weather environment . Wea. Forecasting , 25 , 1052 – 1081 , https://doi.org/10.1175/2010WAF2222390.1 . 10.1175/2010WAF2222390.1 Coleman , T. A. , and K. R. Knupp , 2011 : Radiometer and profiler analysis of the effects of a bore and a solitary wave on the stability of the nocturnal boundary layer . Mon. Wea. Rev. , 139 , 211 – 223 , https://doi.org/10.1175/2010MWR3376.1 . 10

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David B. Parsons, Kevin R. Haghi, Kelton T. Halbert, Blake Elmer, and Junhong Wang

. Mitchell , and K. M. Labas , 1997 : The Great Plains low-level jet during the warm season of 1993 . Mon. Wea. Rev. , 125 , 2176 – 2192 , https://doi.org/10.1175/1520-0493(1997)125<2176:TGPLLJ>2.0.CO;2 . 10.1175/1520-0493(1997)125<2176:TGPLLJ>2.0.CO;2 Baines , P. G. , 1984 : A unified description of two-layer flow over topography . J. Fluid Mech. , 146 , 127 – 167 , https://doi.org/10.1017/S0022112084001798 . 10.1017/S0022112084001798 Baines , P. G. , 1995 : Topographic Effects in

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Samuel K. Degelia, Xuguang Wang, and David J. Stensrud

near the ongoing surface-based convection, convective-scale regions along the borders of the storms are moistened by the final assimilation cycle ( Figs. 17b,h ). This moisture impact is maximized at 600 hPa ( Fig. 18 ). Assimilating wind profilers and rawinsonde observations produces similar effects near the ongoing convection ( Figs. 17d,f ), though additional moisture is already present due to the effects discussed previously. The additional moisture from assimilating Doppler lidar and surface

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Manda B. Chasteen, Steven E. Koch, and David B. Parsons

and surface-based CAPE ( Figs. 10h,i ). To our knowledge, no prior studies have examined the influence that such prominent moisture plumes have on nocturnal convection within central Texas. The effects of baroclinicity on the LLJ structure are more pronounced within regions of strongly sloped terrain, which were spatially varying owing to the complex topography of west Texas. Using the inference that spatial gradients in buoyancy generate horizontal vorticity, Gebauer et al. (2018) explained

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Alan Shapiro, Evgeni Fedorovich, and Joshua G. Gebauer

decrease in from 1000 to 600 km nearly doubles from about 5 to 10 cm s −1 . Consistent with our previous discussion, the pattern descends with time, and the duration of low-level ascent is longer for smaller N and larger λ. These results suggest competing effects of scale on vertical parcel displacements: a smaller λ increases net displacements by increasing , but decreases net displacements by shortening the ascent phase. As we will see, the former effect is more important than the latter, at

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Bart Geerts, David Parsons, Conrad L. Ziegler, Tammy M. Weckwerth, Michael I. Biggerstaff, Richard D. Clark, Michael C. Coniglio, Belay B. Demoz, Richard A. Ferrare, William A. Gallus Jr., Kevin Haghi, John M. Hanesiak, Petra M. Klein, Kevin R. Knupp, Karen Kosiba, Greg M. McFarquhar, James A. Moore, Amin R. Nehrir, Matthew D. Parker, James O. Pinto, Robert M. Rauber, Russ S. Schumacher, David D. Turner, Qing Wang, Xuguang Wang, Zhien Wang, and Joshua Wurman

precipitation cycle in convection-resolving and non-convection-resolving mesoscale models . Mon. Wea. Rev. , 135 , 3456 – 3473 , doi: 10.1175/MWR3467.1 . 10.1175/MWR3467.1 Coleman , T. A. , and K. R. Knupp , 2011 : Radiometer and profiler analysis of the effects of a bore and a solitary wave on the stability of the nocturnal boundary layer . Mon. Wea. Rev. , 139 , 211 – 223 , doi: 10.1175/2010MWR3376.1 . 10.1175/2010MWR3376.1 Colman , B. R. , 1990 : Thunderstorms above frontal surfaces in

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Samuel K. Degelia, Xuguang Wang, David J. Stensrud, and Aaron Johnson

the thermodynamic profile. A sounding valid 45 min before CI that has been modified for the two profiles of vertical velocity is shown in Fig. 14 . The one-dimensional model to modify a sounding is taken from Stensrud and Maddox (1988) and only considers the effects of vertical velocity and latent heating. The governing equations are where is designed to maintain saturation and is defined as Other terms include as the latent heat of condensation, as the specific heat at constant pressure

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