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Jessica D. Lundquist, Justin R. Minder, Paul J. Neiman, and Ellen Sukovich

observations [Parameter-Elevation Regressions on Independent Slopes Model (PRISM); Daly et al. 1994 ]. Second, we examine how processes not included in the idealized model, specifically blocking as characterized by the Sierra barrier jet (SBJ), relate to spatial patterns of precipitation. Finally, we discuss implications for basin hydrology. Throughout the paper, we discuss spatial patterns but particular emphasis is put on variations in precipitation accumulation with elevation, since this has the

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Michael L. Kaplan, Christopher S. Adaniya, Phillip J. Marzette, K. C. King, S. Jeffrey Underwood, and John M. Lewis

events. Cloudiness estimates from the Total Ozone Mapping Spectrometer (TOMS) instrument were consistent with the number and placement of the filaments. These initial results have been examined in greater detail by Zhu and Newell (1994 , 1998) . The basic idea of atmospheric rivers was further explored by Ralph et al. (2004) in conjunction with the California Landfalling Jets (CALJET) experiment and the Pacific Landfalling Jets (PACJET) experiment projects that included more detailed

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Amin K. Dezfuli, Benjamin F. Zaitchik, Hamada S. Badr, Jason Evans, and Christa D. Peters-Lidard

; Kahya 2011 ; Dezfuli et al. 2010 ; Donat et al. 2014 ). At the regional scale, two low-level topographically driven jets have been found to modulate climate variability over the area: the Shamal winds and the Zagros barrier jet (ZBJ). The Shamal winds flow north-northwesterly, parallel to the Zagros Mountains toward the Persian Gulf, and are most notably present during winter and summer. The relative intensity and spatial expansion of three pressure cells contribute to the formation and intensity

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Isidora Jankov, Jian-Wen Bao, Paul J. Neiman, Paul J. Schultz, Huiling Yuan, and Allen B. White

MSL at 2200 UTC 29 December to near the surface at 1600 UTC 30 December, followed by enhanced southwesterly flow and multiple low-level jets (LLJs) in the warm sector. Concurrent S-band radar observations at CZD ( Fig. 3b ) documented mostly NBB rain during the warm frontal descent and a mix of NBB and BB rain in the warm sector ( Table 1 ). The integrated water vapor (IWV) at BBY attained its maximum values (2.5–3.5 cm, Fig. 3c ) in the strong warm-sector flow, indicative of atmospheric river

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Paul J. Neiman, F. Martin Ralph, Gary A. Wick, Jessica D. Lundquist, and Michael D. Dettinger

1. Introduction The pre-cold-frontal low-level jet (LLJ) residing at ∼1 km MSL (e.g., Palmén and Newton 1969 ; Browning and Pardoe 1973 ; Carlson 1991 ) is typically part of a broader region of generally poleward heat transport within the warm sector of extratropical cyclones that is referred to as the “warm conveyor belt” (e.g., Browning 1990 ; Carlson 1991 ). The warm conveyor belt transports both sensible and latent heat, balancing the equatorward transport of comparatively cool, dry

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Xiaokang Wang, Xiquan Dong, Yi Deng, Chunguang Cui, Rong Wan, and Wenjun Cui

the meso- β -scale convective systems ( Zhang et al. 2004 ). Quite often, there is a low-level jet (LLJ; wind speed greater than 12 m s −1 at 850 or 700 hPa) with a scale of hundreds of kilometers located on the south side of the mei-yu front, which advects great amounts of warm, moist air into the mei-yu frontal zone and increases instability energy. Statistical results reveal that 79% of LLJs are accompanied by rainstorms during the mei-yu period ( Wang et al. 2003 ), while 83% of the

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Hui Wang, Rong Fu, Arun Kumar, and Wenhong Li

on linear regressions of the 60-yr data versus the Southeast summer precipitation index ( Fig. 2a ). The drought-related circulation is dominated by positive upper-troposphere height anomalies over the central United States and negative zonal wind anomalies over the southern states ( Fig. 4a ), highlighting the northward shift of the upper-level jet. At the lower level, the anticyclonic circulation enhances the Great Plains low-level jet and moisture transport from the Gulf of Mexico to the

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Allen B. White, Paul J. Neiman, F. Martin Ralph, David E. Kingsmill, and P. Ola G. Persson

1. Introduction The overarching goal of the California Land-Falling Jets Experiment (CALJET; Ralph et al. 1998 ) was to help improve the 0–24-h forecasts of damaging weather impacting the western United States, with a particular emphasis on the coast of California. This goal is being pursued further and expanded to other West Coast states through the ongoing efforts of the Pacific Land-Falling Jets Experiment (PACJET; for more information on PACJET, see http

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F. Martin Ralph, Jason M. Cordeira, Paul J. Neiman, and Mimi Hughes

across eight sites known as the Northern Sierra 8-Station Index (NS8I; Fig. 1 ). Numerous studies suggest that a majority of cool-season precipitation in this region occurs in conjunction with winter storms and their interaction with the complex topography in association with landfalling atmospheric rivers (ARs) and terrain-locked Sierra barrier jets (SBJs; e.g., Dettinger 2004 ; Galewsky and Sobel 2005 ; Ralph et al. 2006 , 2011 , 2013a ; Kim and Kang 2007 ; Reeves et al. 2008 ; Guan et al

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Paul J. Neiman, F. Martin Ralph, Benjamin J. Moore, and Robert J. Zamora

as the blue rectangle in Fig. 2a . Two atmospheric phenomena significantly modulate the distribution of precipitation, high-altitude snowpack, and runoff in the mountains surrounding California’s northern CV: terrain-locked Sierra barrier jets (SBJs) and transient atmospheric rivers (ARs) (e.g., Dettinger 2004 ; Galewsky and Sobel 2005 ; Ralph et al. 2006 ; Kim and Kang 2007 ; Reeves et al. 2008 ; Guan et al. 2010 ; Lundquist et al. 2010 ; Smith et al. 2010 ; Neiman et al. 2008b , 2010

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