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Charles E. Konrad II

work on cold-air outbreaks has examined the synoptic development associated withsmall samples of strong outbreaks. In this study, a synoptic climatology of cold-air outbreaks is developed froma large outbreak sample displaying a wide range of intensities over the southeastern United States. Relationshipsare developed between the intensity of cold-air outbreaks and the magnitude of planetary- and synoptic-scalesurface temperature, pressure, and 500-mb height anomalies over North America. These

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David A. Peterson, Edward J. Hyer, James R. Campbell, Jeremy E. Solbrig, and Michael D. Fromm

governing the state of stratospheric aerosols and affecting global climate. The current understanding of UTLS smoke injection from pyroCb is based on individual fires observed in the mid- and upper-latitude forests of North America, Australia, and Asia (e.g., Fromm et al. 2006 , 2010 , 2012 ). PyroCb have been identified as the source of several UTLS aerosol layers previously presumed to be of volcanic origin ( Fromm et al. 2010 ). Remote sensing–based studies reveal that pyroCb anvils have distinct

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Lance F. Bosart, Gregory J. Hakim, Kevin R. Tyle, Mary A. Bedrick, W. Edward Bracken, Michael J. Dickinson, and David M. Schultz

analysis is used to track coherent transient potential vorticity (PV) anomalies andshow their qualitative interaction with the planetary-scale flow. SS93 is attributed to the interaction and eventualmerger of strong PV anomalies embedded in the northern and southern branches of the westerlies in a backgroundconfluent northwesterly flow associated with an amplifying positive-phase Pacific-North American flow pattern.The northern PV anomaly originates in southwestern Canada on 18 February and

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Stanley G. Benjamin, Stephen S. Weygandt, John M. Brown, Ming Hu, Curtis R. Alexander, Tatiana G. Smirnova, Joseph B. Olson, Eric P. James, David C. Dowell, Georg A. Grell, Haidao Lin, Steven E. Peckham, Tracy Lorraine Smith, William R. Moninger, Jaymes S. Kenyon, and Geoffrey S. Manikin

RAP (versions 1 and 2) is about 3.5 times larger than that used for the RUC, covering Alaska, the Caribbean Sea, and virtually all of North America ( Fig. 1 ). The horizontal domain has been expanded even further in version 3 of the RAP (RAPv3; Fig. 1 ) so that it matches the domain of the North American Mesoscale Forecast System (NAM; Janjić and Gall 2012 ). With this domain change from that of the RUC, the Rapid Refresh is able to provide hourly updated NWP guidance out to 18 h and situational

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Scott A. Isard, James R. Angel, and Geoffrey T. VanDyke

1. Introduction Weather in the Great Lakes region of North America is generally characterized by an alternating series of low and high pressure systems moving eastward in a prevailing westerly circulation. These cyclones, with their attendant winds, clouds, precipitation, and temperature phenomena, account for much of the inclement weather within this continental interior region. The storms not only govern much of the variability of day-to-day weather, but their frequency, paths, and area of

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James S. Boyle and Lance F. Bosart

MAY 1983 JAMES S. BOYLE AND LANCE F. BOSART 1025A Cyclone/Anticyclone Couplet over North America: An Example of Anticyclone Evolution JAMES S. BOYLE~ AND LANCE F. BOSARTDepartment of Atmospheric Science, State University of New York at Albany, Albany, NY 12222(Manuscript received 2 June 1982, in final form 8 February 1983)ABSTRACTA detailed case study has been made of a

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Mingyue Chen and Arun Kumar

1995 ; Barnston and Smith 1996 ; Lau 1997 ; Trenberth et al. 1998 ; Kumar and Hoerling 1998 ; DelSole and Shukla 2006 ; National Research Council 2010 ). For the climate variability over North America (NA), the mean signal of winter precipitation response to the anomalous warm ENSO SSTs includes below-normal conditions over the northern United States and above-normal conditions across the southern part of the United States ( Ropelewski and Halpert 1986 , 1987 , 1989 ; Livezey et al. 1997

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Salvatore Pascale and Simona Bordoni

1. Introduction The seasonal cycle of rainfall over northwestern Mexico and the southwestern United States is dominated by the North American monsoon (NAM), a distinctive summertime circulation characterized by the following features: a sharp rainfall increase in early July after a very dry June ( Higgins et al. 1997 ), the establishment of a mid- to upper-level monsoon anticyclone centered over New Mexico ( Adams and Comrie 1997 ), a reversal in lower-level winds from northwesterly to

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John F. Mejia, Michael W. Douglas, and Peter J. Lamb

1. Introduction a. Background The North American monsoon is characterized by rainfall events related to synoptic and subsynoptic atmospheric systems during summer (mid-June to September) over the southwestern United States and northwestern Mexico. Accurate forecasting of rainfall and wind fields on diurnal-to-intraseasonal time scales inside the North American monsoon domain requires correct simulations not only on continental-to-synoptic scales, but also of

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David J. Gochis, Alejandro Jimenez, Christopher J. Watts, Jaime Garatuza-Payan, and W. James Shuttleworth

1. Introduction a. Background The semiarid climate of southwestern North America presents weather and climate forecasting challenges equally as unique as the landscape itself. Recent years have seen an increased interest in diagnosing and modeling the physical processes controlling the regional climate and its associated modes of variability. The regional streamflow regime becomes increasingly dependent on warm-season precipitation as one travels southward into western Mexico ( Gochis et al

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