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Nina S. Oakley and Kelly T. Redmond

commonly develop over the eastern Pacific and North America and disrupt the westerly flow. These can lead to the development of quasi-barotropic, slow-moving closed-low features ( Weaver 1962 ; Monteverdi 1976 ). Previous work has examined the spatial and seasonal distributions and durations of 200-hPa cutoff lows in the Northern Hemisphere ( Kentarchos and Davies 1998 ; Nieto et al. 2005 ) and the spatial and temporal distribution of 500-hPa closed lows in the Northern Hemisphere ( Bell and Bosart

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Kristen J. Guirguis and Roni Avissar

of thunderstorm activity ( Easterling 1990 ), developing a statistical rainfall forecasting model ( Carter and Elsner 1997 ), linking synoptic-scale circulation patterns to precipitation anomalies ( Diem 2006 ), developing an index of North American monsoon (NAM) variability ( Gutzler 2004 ), identifying snow–NAM teleconnections ( Ellis and Hawkins 2001 ; Hawkins et al. 2002 ), elucidating atmosphere–rainfall relationships ( Diem and Brown 2006 ), and many others. However, past PCA

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Guillem Candille

exchange their ensemble data in order to build a global multiensemble. North America endows itself with its own multiensemble. This paper presents a study on the North American Ensemble Forecast System (NAEFS). That multiensemble project was born in February 2003 when the National Oceanic and Atmospheric Administration (NOAA), the Meteorological Service of Canada (MSC), and the National Meteorological Service of Mexico concluded a high-level agreement about joint ensemble research and development work

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Timothy J. Lang, David A. Ahijevych, Stephen W. Nesbitt, Richard E. Carbone, Steven A. Rutledge, and Robert Cifelli

1. Introduction The intensive observation period (IOP) of the North American Monsoon Experiment (NAME; Higgins et al. 2006 ) took place during July and August of 2004. A major component of the IOP was observations from a multiradar network placed in tier I, the core monsoon region consisting of the Gulf of California (GoC) and the Sierra Madre Occidental (SMO) in northwestern Mexico ( Higgins et al. 2006 ). The network, depicted in Fig. 1a , consisted of three radars: the National Center for

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Chunmei Zhu, Tereza Cavazos, and Dennis P. Lettenmaier

1. Introduction The North American monsoon (NAM) is a remarkable phenomenon that results in a pronounced increase of precipitation from extremely dry spring conditions to much wetter summers over much of the semiarid and arid areas of the southwestern United States (SW) and northwestern Mexico (NW Mexico). The North American monsoon system (NAMS), which develops over low-latitude continental regions in response to seasonal changes of the thermal contrast between the continent and adjacent

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Paul J. Neiman, Ellen M. Sukovich, F. Martin Ralph, and Mimi Hughes

barrier jet paralleling the long axis of the high terrain. Barrier jet flows, which are maintained by a statically stable pressure ridge dammed against the windward slope, have been documented across North America (and elsewhere), including Appalachia (e.g., Bell and Bosart 1988 ), the Rockies (e.g., Dunn 1992 ; Colle and Mass 1995 ; Cox et al. 2005 ), coastal Alaska and British Columbia (e.g., Loescher et al. 2006 ; Olson et al. 2007 ; Yu and Bond 2002 ; Overland and Bond 1995 ), the Pacific

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J. Brant Dodson, Marilé Colón Robles, Jessica E. Taylor, Cayley C. DeFontes, and Kristen L. Weaver

1. Introduction On 21 August 2017, North America experienced a total solar eclipse, with the umbral shadow passing across the contiguous United States from the West to East Coasts ( Fig. 1 ). It was the first total solar eclipse since 1979 for which totality was visible from the contiguous United States. The path of totality crossed the west coast of Oregon at 1716 UTC, moved northwest to southeast across 14 states, and exited the eastern coast of South Carolina at 1849 UTC. Because the eclipse

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Emily A. Slinskey, Paul C. Loikith, Duane E. Waliser, and Alexander Goodman

predecessor MERRA ( Rienecker et al. 2011 ; Reichle et al. 2017 ). The method for merging observed precipitation into MERRA-2 assimilates aerosols and integrates MERRA-Land reanalysis for correction ( Reichle et al. 2017 ). Estimates are further merged with precipitation generated by the MERRA-2 atmospheric general circulation model weighted according to latitude. MERRA-2 is freely available via the GES DISC. e. NARR The North American Regional Reanalysis (NARR) is based on the regional Eta model and its

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AUGVST, 1919 MONTHLY WEATHER REVIEW.WEATHER OF THE MONTH.WEATHER OF NORTH AMERICA AND ADJACENT OCEANS.583GENERAL CONDITIONS.By A. J. HENRY, Meteorologist.The ocean highs which become firmly established in the Northern Hemisphere in July begin to contract in area and the baronietric level begins to i n k in August av continental prevsures increare somewhat. The continen- tal low pre3sure of Asia increases 0.05 to 0.10 incher, and in general the annual swing in the pressure from summer to winter

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A. J. HENRY

APRIL, 1919. MONTHLY WEATHER REVIEW. 255THE WEATHER OF THE MONTH.WEATHER OF NORTH AMERICA AND ADJACENT OCEANS.GENERAL CONDITIONS.A. J. HENRY, Meteorologist.The distribution of mean pressure in the Northern Hemisphere for April indicates the beginning of the dis- solution of the great continental hi lis antl the buildingNorth Atlantic and the Aleutian LOW of the North Pacific, respectively, are still in evidence, although the former now estends southwestward almost to the Canadian Maritime

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