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

few studies that examine the combined effects of both pathways (i.e., land and aerosol effects) on lightning and precipitation. A new observational study ( Kar and Liou 2019 ) indicated that both land and aerosol effects should be considered to explain the cloud-to-ground lightning enhancements over the urban areas. Modeling studies have shown that land-cover changes increase precipitation over the upstream region but decrease it over the downstream region, while the aerosol effect was opposite

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

Schumacher 2016 ), but this was not necessarily true for this case. It should also be noted that while the LLJ does play a major role below 2 km, especially the lowest 1 km, other effects including radiative cooling at night and surface exchange of moisture impact ΔMSE but quantification of their relative influences is not possible here. For example, temperature advection by the LLJ may have sustained warmer temperatures than would have otherwise occurred under the sole influence of radiative cooling

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

reflectivity structure, the simulated MCS closely resembled the observed system during its later stages (i.e., after it had moved into Texas), but the early hours of the simulation were complicated by erroneous convection that formed in central Oklahoma shortly after initialization. The development of this convection was caused by persistent, regional errors in the low-level dewpoint field within the RAP ICs, which produced a localized region of CAPE 2000 J kg −1 ( Fig. 9 ) in central Oklahoma, as

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

to descend back to their initial heights. Given that these disturbances can extend for lengths of hundreds of kilometers, as indicated by the radar fine lines, these results suggest that large areas of upward-displaced air (of order 10 000 km 2 or greater) can occur behind the leading edge of these disturbances. This regional destabilization of the environment is similar to the proposed gregarious nature of tropical convection by Mapes (1993) , although our result is from a bore generated in

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Stanley B. Trier, James W. Wilson, David A. Ahijevych, and Ryan A. Sobash

) in lower-tropospheric baroclinic zones. Using data from the Oklahoma–Kansas Preliminary Regional Experiment for STORM-Central (PRE-STORM; Cunning 1986 ), several studies (e.g., Blanchard 1990 ; Stumpf et al. 1991 ; Fortune et al. 1992 ; Smull and Augustine 1993 ) examined mature stage MCSs whose overall convective structure is more complex (e.g., three-dimensional) than that in typical squall lines. Such systems often include elevated convection (e.g., Corfidi et al. 2008 ), where the

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Alan Shapiro, Evgeni Fedorovich, and Joshua G. Gebauer

LLJ), or along or north of the intersection of an LLJ with a cold front, are more or less clear, but the mechanisms that force ascent on a lateral flank of an LLJ are still not well understood. In this regard, we believe that the recent Pu and Dickinson (2014) explanation for such a mechanism is not wholly satisfactory. In a study of vertical motions in Great Plains LLJs using a North American Regional Reanalysis (NARR) June–July climatology, Pu and Dickinson (2014) suggest that after midnight

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Tammy M. Weckwerth and Ulrike Romatschke

precipitation. This paper uses radar-derived quantitative precipitation estimates (QPEs) to illustrate where and when the precipitation during PECAN occurred and uses North American Regional Reanalysis (NARR) composites to assess why the PECAN precipitation patterns and timing occurred. It has been known for more than a century that the diurnal pattern of summertime precipitation in the U.S. Great Plains has a strong nocturnal maximum (e.g., Kincer 1916 ; Bleeker and Andre 1951 ; Wallace 1975

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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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Tammy M. Weckwerth, John Hanesiak, James W. Wilson, Stanley B. Trier, Samuel K. Degelia, William A. Gallus Jr., Rita D. Roberts, and Xuguang Wang

geographically centered around Hays, Kansas ( Geerts et al. 2017 ). The NCI events examined in this study occurred within the PECAN domain delineated by the rectangular region in Fig. 1 . Identification of NCI events. This study used the 3D regional mosaic of 0.5°-elevation-angle radar data ( Earth Observing Laboratory 2016a ) produced for PECAN to identify the NCI events. The regional radar mosaic included data from both the national network of WSR-88Ds located in the central Great Plains and NCAR’s S

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Coltin Grasmick, Bart Geerts, David D. Turner, Zhien Wang, and T. M. Weckwerth

mechanisms accelerating the leading convective line. Their study predominantly focused on internal factors such as microphysics and kinematics within the storm and their effects on downdraft velocities, hydrometeor loading, and evaporation efficiency; all of these factors strengthen cold pools and promote forward surging. The present case study similarly investigates storm propagation but focuses on the characteristics of the MCS outflow boundary and the depth and location of vertical air displacements

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