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Thomas R. Parish

. Analyses from 0000 UTC 3 Jun 2015 NAM that show (a) sea level pressure (hPa), (b) 950-hPa heights (black lines; m) and temperatures (red dashed lines; °C), (c) 850-hPa heights and temperatures, and (d) 600-hPa heights and temperatures. The 850-hPa height field ( Fig. 5c ) also shows a PGF across the southern Great Plains states although not as strong as that at 950 hPa. Isotherms again reflect the diabatic heating of the Great Plains, running primarily in a north–south direction and parallel to terrain

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Thomas R. Parish and Richard D. Clark

heating thus occurs at a particular isobaric level over the sloping Great Plains where the warmest air is found over the elevated terrain to the west. As a result, an isobaric temperature gradient becomes established with warm air to the west and cooler air to the east. The magnitude of the isobaric temperature gradient is largest at the lowest levels of the atmosphere. Observations from 20 June 2015 show that isobaric temperature gradients arising from the diabatic heating of the sloping terrain

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Thomas R. Parish

diabatic heating of the atmosphere above the level of the jet over the Great Plains in the establishment of the prerequisite background PGF is more important than any enhancements due to diurnal oscillations. The critical role of heating at levels above the jet core requires the LLJ to be a warm-weather phenomenon. The above view recognizes that diurnal variations in the PGF (the Holton mechanism) do occur and can be of importance in the actual wind profile and height of the jet but are small at the

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Shushi Zhang, David B. Parsons, and Yuan Wang

gravity waves. For example, Stephan et al. (2016) found that deep, intense latent heat release within the precipitation systems is the key forcing mechanism for the observed gravity waves, which may potentially remotely interact with and enhance active precipitation. Previous work by Pandya and Durran (1996) show that the distribution of diabatic heating and cooling can force these waves. The lifting of the gravity wave could also cool and moisten the lower troposphere to provide more favorable

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Rachel L. Miller, Conrad L. Ziegler, and Michael I. Biggerstaff

the anvil combined with diabatic heating associated with cloud and precipitation formation in the CL and TS region ( Rutledge et al. 1988 ). Decreasing q υ values are noted within the 0–4 km layer of drier rear inflow and mesoscale subsidence at the leading edge of the TS region. The warmest air in advance of the MCS in θ e ( Fig. 16c ) and θ w ( Fig. 16d ) resides within the 0.5–2 km postfrontal ERL ( Fig. 2 ). Strong westerly shear ( Fig. 16e ) entering the cross-sectional plane (i

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

topography are discussed in section 5 . The influences of environmental heterogeneity and solar heating on the convective evolution are presented in section 6 . Finally, a summary of this study and proposed avenues for future research are found in section 7 . 2. Case description Two convective clusters developed in central Oklahoma at approximately 0300 UTC 1 6 October 2014. These clusters quickly grew upscale into a quasi-linear convective system (QLCS), and the western portion of the system

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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

over the plains. In effect, such propagating waves or singular “buoyancy bores” ( Mapes 1993 ; Mapes et al. 2003 ; Schumacher 2009 ) may be reenergized through a convective feedback, driven by deep latent heat release in emerging MCSs ( Tripoli and Cotton 1989a , b ; Tuttle and Davis 2006 ; Fovell et al. 2006 ; Trier et al. 2010 ). Other studies have shown that daytime heating over the elevated terrain of the Rockies generates mesoscale potential vorticity (PV) anomalies that persist even in

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Matthew D. Parker, Brett S. Borchardt, Rachel L. Miller, and Conrad L. Ziegler

remained roughly 2.5 km as of the 0430 UTC PECAN sounding ( Fig. 3c , green profile), the surface cold pool inferred from Miller (2018) ’s diabatic Lagrangian analyses far exceeded this depth by 0500 UTC. In keeping with the hypothesized transition to surface-based convection, Miller et al. (2019) ’s multi-Doppler syntheses support that streamlines entered the MCS’s updrafts from progressively lower altitudes over time. Unfortunately, the MCS began its most prolific severe wind production as it

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