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Robert S. Hahn and Clifford F. Mass

their moisture variables, even when the synoptic-scale flow is well forecast. An essential question is whether the source of these problems lies in deficiencies in microphysics, numerics, or some other model aspect, such as the boundary layer parameterization or initialization. Attempts to address these problems through more sophisticated model microphysics parameterizations have improved model verification but substantial deficiencies still exist. For example, Garvert et al. (2005a , b

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Roberto Mera, Arlene G. Laing, and Frederick Semazzi

1. Introduction Weather and climate in the African Sahel are dominated by two major wind systems: the southwesterly West African monsoon (WAM) and the northeasterly (harmattan) trade winds emanating from the Sahara Desert. As the primary driver for precipitation, the WAM is a vital component of the socioeconomic environment of the region. In addition to the agricultural benefit of the rains, the public health sector is affected through the relationship between the onset of monsoon moisture and

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John D. Frye and Thomas L. Mote

. 2003 ; Trier et al. 2004 ; Holt et al. 2006 ). Studies have shown that when distinct surface heterogeneities were present, mesoscale circulation patterns developed similar to the mesoscale circulation patterns evident during a land–sea breeze ( Pielke 2001 ; Chaboureau et al. 2004 ). One surface characteristic that has been shown to create these patterns is soil moisture, which is the focus of the present study. Soil moisture heterogeneities also have been shown to have a feedback to

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Qianwen Luo and Wen-wen Tung

1. Introduction Atmospheric rivers (ARs) are narrow channels of enhanced moisture flux in the atmosphere ( Newell et al. 1992 ; Zhu and Newell 1994 ). They perform ocean-to-ocean and ocean-to-land moisture transports ( Newman et al. 2012 ), accounting for >90% of the total meridional moisture flux in the midlatitudes ( Zhu and Newell 1998 ). They are typically parts of the warm conveyor belts (WCBs), which are strongly ascending airstreams near winter extratropical cyclones. The WCBs transport

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Christian Sutton, Thomas M. Hamill, and Thomas T. Warner

assessment of the state of the land surface may affect the subsequent weather forecast. As the ground surface heats up during the day, sensible energy is transferred to the atmosphere, moisture evaporates from the soil or transpirates from plants (latent heating), and the soil below is heated. The partitioning of the available energy among sensible, latent, and ground heat fluxes depends on many variables, in particular soil moisture. Generally, the drier the soil, the smaller the daytime latent heat

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Qingfang Jiang and James D. Doyle

1. Introduction Moist processes have been largely ignored in the majority of mountain-wave studies, partially because of the complexity associated with moisture and microphysical processes. Studies of the interaction between moist airflow and mesoscale topography can be broadly classified into two categories. The first category includes quasi-analytical studies with highly simplified representations of moist processes. For example, a set of two-dimensional steady-state linear wave solutions

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T. N. Krishnamurti, S. Pattnaik, and D. V. Bhaskar Rao

through the temperature and moisture tendencies as control variables. Similar analysis has been provided by JMA and BMRC in published ( Davidson and Weber 2000 ) and unrefereed reports ( Tada 2002 ; Tauchi et al. 2003 ). The inclusion of initial rains, based on Newtonian relaxation or using variational data assimilation, has only seen limited application for very high resolution mesoscale models ( Ishikawa 2002 ; Koizumi et al. 2005 ; Macpherson 2001 ; Jones and Macpherson 1997 ). From the

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Russ S. Schumacher and Thomas J. Galarneau Jr.

1. Introduction Recent studies have analyzed regions of heavy rainfall that occur ahead of recurving tropical cyclones (TCs), in which tropical moisture transported ahead of the TC enhances the precipitation in midlatitude convective systems ( Wang et al. 2009 ; Galarneau et al. 2010 ; Schumacher et al. 2011 ). These situations were termed predecessor rain events (PREs) by Galarneau et al. (2010) . PREs occur when tropical moisture is transported poleward of the TC and is lifted along a low

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Edward I. Tollerud, Fernando Caracena, Steven E. Koch, Brian D. Jamison, R. Michael Hardesty, Brandi J. McCarty, Christoph Kiemle, Randall S. Collander, Diana L. Bartels, Steven Albers, Brent Shaw, Daniel L. Birkenheuer, and W. Alan Brewer

1. Introduction Previous studies of the low-level jet (LLJ) have helped to establish its role as the major conveyor of low-level moisture from the Gulf of Mexico into the central United States ( Stensrud 1996 ; Higgins et al. 1996 ). Higgins et al. (1997) estimate that the contribution of the LLJ to low-level moisture transport over the central plains is almost 50% above average non-LLJ values. A major factor in the LLJ contribution to central plains precipitation is the relationship between

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Katja Friedrich, David E. Kingsmill, Cyrille Flamant, Hanne V. Murphey, and Roger M. Wakimoto

al. 1995 ; Fovell 2005 ), and drylines (e.g., Fujita 1970 ; Koch and McCarthy 1982 ; Schaefer 1986 ; Hane et al. 1997 ; Murphey et al. 2006 ) have received the largest amount of attention in terms of documenting their kinematic and moisture characteristics for convective weather forecasting applications. Precipitating cold fronts, particularly those associated with narrow cold frontal rainbands, have been examined in this context as well (e.g., James and Browning 1979 ; Hobbs and Persson

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