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Jared A. Rackley and John A. Knox

( Hartfield et al. 1996 ; Kramer 1997 ; Hartfield 1998 ). Classification of each event was based on the strength and location of the parent high and whether or not precipitation was falling within 6 h of onset at the center station of the first line activated ( Fig. 2 ). These criteria were determined using a combination of surface observations and North American Regional Reanalysis (NARR) data ( Mesinger et al. 2006 ), and defined six CAD cases as discussed in B03 : Classical diabatically enhanced

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Andrew C. Winters, Lance F. Bosart, and Daniel Keyser

Diffenbaugh 2014 ; Grotjahn et al. 2016 ). Numerous studies have sought relationships between cool season ETEs over North America and modes of intraannual climate variability as part of an effort to understand the large-scale meteorological patterns associated with the development of ETEs ( Table 1 ). For example, prior work has identified relationships between ETEs and the phase of the Pacific–North American pattern (PNA), the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), and the Madden

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G. S. Young, T. N. Sikora, and N. S. Winstead

the Bering Sea with the remainder from the east coast of North America between the east coast of Florida and New England. The SAR on board RADARSAT-1 is C band (5.6 cm) and right looking with horizontal–horizontal polarization (HH-pol). The RADARSAT-1 SAR has various sensor modes but the one employed here is the ScanSAR wide mode, which has a swath width of approximately 500 km and a resolution of 100 m. The SAR imagery presented herein have been smoothed from 100- to 600-m resolution in order

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Pamela L. Heinselman and David M. Schultz

storm development and the associated environmental conditions are important to public safety and economics. Arizona’s summer wet season occurs in response to the North American monsoon (NAM), a reversal in circulation at low and midlevels over Mexico and the Desert Southwest every July and August (e.g., Douglas et al. 1993 ; Adams and Comrie 1997 ). At low levels, a thermal low forms over the Colorado Plateau ( Tang and Reiter 1984 ; Rowson and Colucci 1992 ; Mohr 2004 ), modulating the low

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Lynn McMurdie and Clifford Mass

1. Introduction Intense extratropical cyclones over the North Pacific often impact the west coast of North America with strong winds, heavy precipitation, and major societal impacts. Several times each year, short-term (0 to 48 h) model forecasts of strong North Pacific cyclones are seriously deficient, with position errors measured in the hundreds of kilometers and sea level pressure errors exceeding 15 mb. For example, the National Centers for Environmental Prediction (NCEP) Eta Model 48-h

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Philip J. Klotzbach and William M. Gray

(NAO) ( van Loon and Rogers 1978 ) and a midlatitude wave train pattern closely resembling a positive and slightly eastward-shifted Pacific–North American pattern (PNA) ( Wallace and Gutzler 1981 ). A positive PNA is a typical wintertime midlatitude teleconnection associated with warm ENSO conditions ( Horel and Wallace 1981 ), and the eastward shift of the PNA is likely due to an eastward shift of sea surface temperature anomalies from the central to the east Pacific. A wave train propagates

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Michael E. Charles and Brian A. Colle

1. Introduction a. Background This paper is the second in a series verifying extratropical cyclones within the operational models at the National Centers for Environmental Prediction (NCEP). Charles and Colle (2009 , hereafter Part I) highlighted the performance of the North American Mesoscale (NAM) and Global Forecast System (GFS) models around North America and its adjacent oceans for the 0–60-h forecasts of extratropical cyclones during the 2002–07 cool seasons. Cyclone forecast errors

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Hai Lin, William J. Merryfield, Ryan Muncaster, Gregory C. Smith, Marko Markovic, Frédéric Dupont, François Roy, Jean-François Lemieux, Arlan Dirkson, Viatcheslav V. Kharin, Woo-Sung Lee, Martin Charron, and Amin Erfani

), and the fifth-generation seasonal forecast system of the European Centre for Medium-Range Weather Forecasts (ECMWF SEAS5; Johnson et al. 2019 ). CanSIPS has been an integral part of several international activities related to multimodel ensemble seasonal forecasts, including the North American Multimodel Ensemble (NMME) (e.g., Kirtman et al. 2014 ), the World Meteorological Organization (WMO) Long-Range Forecast Multi-Model Ensemble (e.g., Graham et al. 2011 ), and the multimodel climate

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David Siuta, Gregory West, and Roland Stull

large errors in the estimated hub-height wind. NWP models, such as the Weather Research and Forecasting (WRF) Model ( Skamarock et al. 2008 ), have taken the forefront in wind speed forecast research and can be used to directly forecast winds at hub height to avoid vertical interpolation. WRF has two dynamical cores: the Nonhydrostatic Mesoscale Model (NMM) and the Advanced Research version of WRF (ARW). The NMM core is used by the National Centers for Environmental Prediction (NCEP) North American

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Paul J. Roebber, James M. Frederick, and Thomas P. DeFelice

, the strong composite 500-hPa Pacific jet splits over North America, with the southwesterly (northwesterly) subtropical (polar) jet positioned over the southern United States (northern Canada), leading to confluence downstream of the U.S. midwest. The anomalous nature of this split flow is indicated by the strong positive 500-hPa height anomalies located over Canada ( Figs. 5a and 5b ). Correspondingly, composite surface conditions ( Figs. 6a–d ) were relatively quiescent with broad-scale high

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