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Alan Shapiro, Evgeni Fedorovich, and Joshua G. Gebauer

Rapid Update Cycle (RUC) wind analyses. In a 20-yr climatology of warm season nocturnal CI over the central and southern Great Plains, Reif and Bluestein (2017) found that 24% of the nocturnal CI episodes occurred without a nearby surface boundary. Nearly one-half of these no-boundary (NB) CI episodes were of a linear storm type, the majority of which had a preferred north–south orientation, the same preference exhibited by nocturnal low-level jets (LLJs) over the Great Plains (e.g., Hoecker 1963

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Joshua G. Gebauer, Alan Shapiro, Evgeni Fedorovich, and Petra Klein

the region. The thunderstorms are often elevated, in the sense that storm updrafts develop in an elevated region separated from the surface by a nocturnal stable boundary layer ( Colman 1990 ; Wilson and Roberts 2006 ). One feature associated with the initiation and development of these nocturnal thunderstorms is the Great Plains low-level jet (LLJ) ( Pitchford and London 1962 ; Maddox 1983 ; Astling et al. 1985 ; Trier and Parsons 1993 ; Trier et al. 2006 ; Tuttle and Davis 2006 ). LLJs are

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Thomas R. Parish and Richard D. Clark

1. Introduction The Great Plains low-level jet (LLJ) is among the most scrutinized mesoscale features of the lower atmosphere (e.g., Bonner 1968 ; Bonner and Paegle 1970 ; Mitchell et al. 1995 ; Whiteman et al. 1997 ). Studies have shown that relatively weak southerly winds in the daytime summer boundary layer often become significantly enhanced during the nighttime and early morning hours. A well-defined jet profile becomes established several hundred meters above the surface a few hours

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Thomas R. Parish

1. Introduction The Great Plains Turbulence Research Program was a major field experiment conducted near the town of O’Neill in north-central Nebraska from August through September of 1953 ( Lettau and Davidson 1957 ). A recurring lower-atmospheric feature documented during that study was what is now known as the Great Plains low-level jet (LLJ). Lettau (1967) noted that the LLJ occurred regularly at an elevation about 450 m above the ground, commencing after sunset and reaching a peak speed

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Elizabeth N. Smith, Joshua G. Gebauer, Petra M. Klein, Evgeni Fedorovich, and Jeremy A. Gibbs

1. Introduction Wind maxima called nocturnal low-level jets (NLLJs) often occur during the night in the lowest kilometer of the atmosphere. In the most general sense, the NLLJ is the result of the disruption of the daytime force balance between the Coriolis, pressure gradient, and frictional forces. Once the sun sets, thermally generated turbulence decays, and the stable boundary layer (SBL) forms. The frictional force weakens above the surface, which eliminates the force balance and leads to

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Thomas R. Parish

1. Introduction Nocturnal low-level wind maxima have received considerable attention during the past few decades. In particular, the Great Plains low-level jet (LLJ) has been the topic of extensive study (e.g., Bonner 1968 ; Mitchell et al. 1995 ; Whiteman et al. 1997 ). Wind profiles in the lowest kilometer at Great Plains sites often show profound day-to-night differences. Weak southerly winds in the lowest several hundred meters often persist throughout the daylight hours only to be

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Evgeni Fedorovich, Jeremy A. Gibbs, and Alan Shapiro

1. Introduction The nocturnal low-level jet (LLJ) is an atmospheric boundary layer wind maximum that typically develops under dry and clear conditions after sunset. The jet reaches a peak magnitude a few hours after midnight, and then decays after sunrise with the onset of convective mixing ( Shapiro and Fedorovich 2010 ). LLJs have been observed in many locations throughout the world (see, e.g., Stensrud 1996 ; Baas et al. 2009 ; Van de Wiel et al. 2010 ) but have been most extensively

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

1. Introduction The Great Plains low-level jet (LLJ) is a primarily nocturnal phenomenon of strong southwesterly winds within the planetary boundary layer (PBL) spanning hundreds of kilometers in width and length, and is most frequent and impactful during the warm-season. LLJs provide major contributions to nocturnal convection in the region, such as mesoscale convective systems (MCSs), via convergence of the wind field and advection of moisture and temperature ( Byerle and Paegle 2003 ; Trier

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Stacey M. Hitchcock and Russ S. Schumacher

several different methods of classification, but two distinct categories consistently emerge for events over the central Great Plains. In synoptic-type events, a strong midtropospheric trough and slow moving surface front lead to strong forcing for ascent in a region with southerly flow and associated moisture transport. During the warm season, isentropic ascent of warm, moist air transported by the nocturnal low-level jet (LLJ) can lift an air to saturation on the cool side of a stationary or warm

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

-scale environment favorable for storm formation and maintenance. Data from the North American Regional Reanalysis (NARR) reanalysis at 1800 UTC 1 July 2015 are presented to highlight characteristics of the synoptic-scale condition ( Fig. 2 ). The storm formed east of the short-wave trough located in Nebraska ( Fig. 2a ). The 500 hPa winds exhibit a strong jet stream and upper-level disturbance over Kansas. A surface stationary front stretched from Pennsylvania to a broad region of low pressure in Kansas ( Fig

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