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Russ S. Schumacher and Richard H. Johnson

the heavy rainfall. Events were classified as tropical if they were the direct result of a tropical cyclone or its remnants. While mesoscale processes may be important in all three of these classifications, the distinctions that have been drawn are motivated in part by operational forecasting concerns. Though the ingredients necessary for the development of extreme rainfall are the same regardless of the strength of forcing (e.g., Doswell et al. 1996 ), there are some different challenges

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J. J. Simpson, G. L. Hufford, R. Servranckx, J. Berg, and D. Pieri

Mediterranean Sea ( Chester et al. 1984 ; Dulac et al. 1992 ), and 3) over the tropical North Atlantic Ocean ( Talbot et al. 1986 ; Ozloy et al. 2001 ) is documented well. The resultant atmospheric particles have been studied within the contexts of radiative forcing and climate (e.g., Myhre and Stordal 2001 ), carriers in the biogeochemical cycles of crustal elements (e.g., Chadwick et al. 1999 ), and public health ( Schwartz et al. 1999 ). This paper 1) reviews some satellite-based retrievals of

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Heather Dawn Reeves and David J. Stensrud

; Billings et al. 2006 ; Hoggarth et al. 2006 ) and it is not known whether the timing of VCPs is primarily dictated by synoptic-scale forcing for a larger collection of cases with a wider array of valley and basin sizes and geometries. The aim of this paper is to perform a short-term climatology of persistent VCPs in valleys and basins of differing size, location, and geometry in the western United States to assess the connection between synoptic-scale wave motion and VCP formation, maintenance, and

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Stephen F. Corfidi, Sarah J. Corfidi, David A. Imy, and Allen L. Logan

forward propagation is apparent in the wind profile shown in Fig. 3 . The profile is not only strong, but also nearly unidirectional. Strong, unidirectional wind fields are known to favor coherent motion of storm-scale downdrafts and to promote rapid elongation of the resulting MCS cold pool in the downstream direction ( Corfidi 2003 ). This can strengthen and deepen low-level system-relative inflow and therefore promote convective initiation and sustenance in relatively dry conditions by forcing

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Jean-Raymond Bidlot, Damian J. Holmes, Paul A. Wittmann, Roop Lalbeharry, and Hsuan S. Chen

by forcing WAM with those winds ( Sterl et al. 1998 ) and comparing the results with buoy and altimeter data. It is also done on a routine basis for the monitoring of the ECMWF forecasting system ( Janssen et al. 2000a ). A systematic comparison of wave model results with other models is not often reported. It is usually confined to the initial phase of a new model implementation or when different models are compared in order to select one for operational production. Earlier work on operational

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Ghislain Faure, Philippe Chambon, and Pierre Brousseau

parameterization to simulate convection ( Bechtold et al. 2014 ). It is known that, thanks to a better resolution for orography and a convection-permitting core, AROME can provide more realistic rain fields than its global forcing model ( Clark et al. 2016 ; Seity et al. 2011 ). However, due to the initialization process and the following spinup, along with some usual caveats of mesocale models for rainfall forecasting such as the over (under) estimation of heavy (light) rainfall ( Lean et al. 2008 ; Done et

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William R. Ryerson and Joshua P. Hacker

perhaps a single state or province (i.e., 100 km × 100 km) in real-time operations. Given these limitations, a common approach is to rely on a more sophisticated visibility parameterization that leverages NWP output variables beyond just q c . Examples of these more sophisticated visibility parameterizations are plentiful in both operations and research. Until recently, visibility predictions from the U.S. Air Force’s Mesoscale Ensemble Prediction System (MEPS) used a statistical parameterization

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Huaqing Cai and Robert E. Dumais Jr.

( Figs. 10b,d,f ) subdomains. The diurnal variation of the total number of storms in the Southeast is much stronger than that of the upper Midwest, suggesting different forcing mechanisms are responsible for the storm initiation and evolution in these two subdomains. The timing of new storm initiation in the upper Midwest was much better handled by the model than in the Southeast. In fact, all forecasts for the upper Midwest showed almost simultaneous increases in the total number of storms compared

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Pin-Fang Lin, Pao-Liang Chang, Ben Jong-Dao Jou, James W. Wilson, and Rita D. Roberts

. (2011) , utilizing many of the same data as in this paper, examined the characteristics and evolution of afternoon thunderstorms over Taiwan under weak synoptic-scale forcing (synoptically undisturbed). As will be described later, it was found that sea-breeze flows and anabatic–katabatic flows play an important role in moistening the boundary layer for the initiation of TS A s; similar findings have been reported by Johnson and Bresch (1991) and Chen and Li (1995) . The initial convective

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Ryan P. Aylward and Jamie L. Dyer

the synoptically forced events were produced through convection in the eastern United States during the warm season. Synoptically forced events in their study were defined as events that occurred near a frontal boundary. Schumacher and Johnson (2006) found 93% of synoptic events were convective, but only 25% of the heavy-rain events in their study were primarily of synoptic forcing and normally occurred during the cool season in the eastern United States. A pronounced seasonal difference in

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