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Hristo G. Chipilski, Xuguang Wang, and David B. Parsons

height. The dashed blue line corresponds to . The second part of the probabilistic bore prediction utilizes linear wave theory and estimates whether the environmental conditions are favorable for maintaining the convectively generated atmospheric bore. In particular, the algorithm calculates the ensemble distribution of the Scorer parameter ( Scorer 1949 ) ahead of the density current (i.e., at point ). The example distribution from Fig. 9b shows a sharp decrease in from the surface to 1 km

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Dana Mueller, Bart Geerts, Zhien Wang, Min Deng, and Coltin Grasmick

1. Introduction To a stationary observer, the passage of a bore results in a net increase in the fluid mass overhead, unlike the passage of an internal gravity wave [see 19–22 in Simpson (1997) ]. A bore essentially is a hydraulic jump. Unlike a density (or gravity) current, it transports little mass and does not advect a reservoir of denser fluid. Atmospheric bores are frequently observed to propagate on a surface-based temperature inversion at night or during the early morning hours, and are

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Stacey M. Hitchcock and Russ S. Schumacher

://doi.org/10.1175/MWR-D-13-00167.1 . 10.1175/MWR-D-13-00167.1 Parker , M. D. , B. S. Borchardt , R. L. Miller , and C. L. Ziegler , 2020 : Simulated evolution and severe wind production by the 25–26 June 2015 nocturnal MCS from PECAN . Mon. Wea. Rev. , 148 , 183 – 209 , https://doi.org/10.1175/MWR-D-19-0072.1 . 10.1175/MWR-D-19-0072.1 Parsons , D. B. , K. R. Haghi , K. T. Halbert , B. Elmer , and J. Wang , 2019 : The potential role of atmospheric bores and gravity waves in

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Brian J. Carroll, Belay B. Demoz, David D. Turner, and Ruben Delgado

studies, as they can continuously profile a variety of atmospheric properties from ground-based and airborne platforms. A case study of airborne differential absorption lidar (DIAL) data assimilation by Wulfmeyer et al. (2006) demonstrated major improvement to quantitative precipitation forecasting in the Great Plains. Airborne water vapor lidar has also proven useful in profiling the sharp moisture gradients of drylines and bore waves without steady-state assumptions (e.g., Koch et al. 2008

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Yun Lin, Jiwen Fan, Jong-Hoon Jeong, Yuwei Zhang, Cameron R. Homeyer, and Jingyu Wang

2019 ). There is a lack of studies examining impacts on severe convective storms that produce large hail, tornadoes, and damaging winds, which cause as much annual property damage and more deaths than hurricanes in the United States based on National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center (2012) . Hail produces roughly 60% of the annual average losses in the United States, compared to 20% for both damaging wind and tornadoes ( Gunturi and Tippett 2017

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

. Atmos. Oceanic Technol. , 25 , 1267 – 1287 , https://doi.org/10.1175/2007JTECHA951.1 . 10.1175/2007JTECHA951.1 Koch , S. E. , W. Feltz , F. Fabry , M. Pagowski , B. Geerts , K. M. Bedka , D. O. Miller , and J. W. Wilson , 2008b : Turbulent mixing processes in atmospheric bores and solitary waves deduced from profiling systems and numerical simulation . Mon. Wea. Rev. , 136 , 1373 – 1400 , https://doi.org/10.1175/2007MWR2252.1 . 10.1175/2007MWR2252.1 Lane , T. P. , and

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Kevin R. Haghi, Bart Geerts, Hristo G. Chipilski, Aaron Johnson, Samuel Degelia, David Imy, David B. Parsons, Rebecca D. Adams-Selin, David D. Turner, and Xuguang Wang

defines as a “sudden and usually turbulent passage of water in an open channel from low stage, below critical depth, to high stage, above critical depth.” In the case of the atmosphere, the water is replaced by a stably stratified fluid of air adjacent to the ground. In the AMS definition, “critical” is defined by whether waves can propagate upstream, or if the flow is faster than all wave speeds. The more atmospheric relevant internal wave can arise in a stratified flow when a light fluid, resting

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Shushi Zhang, David B. Parsons, and Yuan Wang

atmospheric bores and gravity waves that are often associated with nocturnal MCS can be found in Haghi et al. (2019) . In this case, an observed and simulated disturbance that formed near and propagating away from a convectively generated cold pool had the characteristics of a bore (strong pressure rise at the surface without a corresponding decrease in the surface temperatures). In contrast to the findings summarized in Haghi et al. (2019) that discuss bores within and just above the SBL, our study

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David M. Loveless, Timothy J. Wagner, David D. Turner, Steven A. Ackerman, and Wayne F. Feltz

able to remove from the nocturnal boundary layer. This results in the layer with greatest instability being above the surface. One potential mechanism for initiating and maintaining elevated convection is atmospheric bores ( Parker 2008 ; French and Parker 2010 ). Bores are a type of gravity wave that form from the interaction of a density current with a stable fluid of lesser density. Bores will form in either a partially blocked system ( Rottman and Simpson 1989 ) or a completely blocked system

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J. W. Wilson, S. B. Trier, D. W. Reif, R. D. Roberts, and T. M. Weckwerth

parameters. The UWKA mostly flew at an elevation of roughly 2.15 km MSL. The primary leg of interest was flown from west to east between 0408 and 0432 UTC. Convection initiation occurred 25 km north of the track at 0405 UTC. Other flight legs helped identify the location of a wind-shift line to be discussed later. Particularly important were Doppler lidar observations from TWOLF and MP3 to help determine vertical wind profiles and cloud base and to detect atmospheric gravity waves. In addition, there was

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