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Julia H. Keller, Christian M. Grams, Michael Riemer, Heather M. Archambault, Lance Bosart, James D. Doyle, Jenni L. Evans, Thomas J. Galarneau Jr., Kyle Griffin, Patrick A. Harr, Naoko Kitabatake, Ron McTaggart-Cowan, Florian Pantillon, Julian F. Quinting, Carolyn A. Reynolds, Elizabeth A. Ritchie, Ryan D. Torn, and Fuqing Zhang

moves poleward and starts to interact with the midlatitude flow ( Fig. 1a ). This results in the formation of a jet streak ( Fig. 1b ) and a poleward deflection of the jet near the transitioning cyclone in conjunction with the development of a ridge–trough couplet ( Fig. 1b ). At the same time, a region of enhanced moisture flux—a so-called atmospheric river ( Zhu and Newell 1998 )—forms ahead of the downstream trough. The ridge–trough couplet continues to amplify, a new cyclone develops farther

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Joaquim G. Pinto, Florian Pantillon, Patrick Ludwig, Madeleine-Sophie Déroche, Giovanni Leoncini, Christoph C. Raible, Len C. Shaffrey, and David B. Stephenson

center. Some of the moisture transported by the feeder airstream is supplied to the base of the warm conveyor belt where it ascends to form precipitation, while the rest remains at low levels, forming the leading edge of an atmospheric river. Lea Eisenstein (KIT) presented a modeling study of the first detected sting-jet windstorm over continental Europe (“Egon” in January 2017). Devastating sting jets are associated with strong wind gusts lasting for a few hours over a distinct region located

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Hilke S. Lentink, Christian M. Grams, Michael Riemer, and Sarah C. Jones

the forecast errors associated with these changes. For mature TCs that make landfall, on the other hand, many (idealized) studies document the influence of either a flat coastal region or an orographic barrier (e.g., Taiwan) on the track and structural development. When a TC vortex impinges on land, regardless of orography, it has two effects: a reduction of moisture supply and an increase of surface roughness. First, when the inner core is still over the ocean, dry air from land is transported

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Tobias Selz, Lucas Fischer, and George C. Craig

interactions of dynamics and moisture in the atmosphere are not fully understood, the observations of power-law scaling allow for a reality check of NWP models and GCMs concerning water vapor variability ( Kahn et al. 2011 ). While this is not a traditional validation measure, a model’s ability to reproduce the observed scale dependence behavior provides a statistical measure of the accuracy of its moist dynamics and physics ( Skamarock 2004 ). In other words, if a model does not reproduce the real

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Christian Barthlott and Corinna Hoose

and simulating clouds in different environments are needed. The COSMO model uses a rotated latitude–longitude grid with terrain-following hybrid height coordinates. Deep convection is resolved explicitly, while shallow convection is parameterized using a modified Tiedtke mass-flux scheme with moisture-convergence closure ( Tiedtke 1989 ). Shallow convection is nonprecipitating and limited to a cloud depth of 250 hPa. Only temperature and moisture are directly affected by shallow convection (for

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Tobias Selz

basically determines the intrinsic limit of weather prediction up to planetary scales. Already Lorenz (1969) suggested this with his experiment C. It has been further confirmed by the sensitivity of the magnitude of a large-scale error after a certain lead time on moisture ( Zhang et al. 2007 ) or on the convection scheme Selz and Craig (2015a) . Indeed, error-growth experiments with global numerical models suffer from the low grid resolution and the need of a parameterization scheme for deep

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Kevin Bachmann, Christian Keil, George C. Craig, Martin Weissmann, and Christian A. Welzbacher

, and G. C. Craig , 2018 : Soil moisture–precipitation coupling over Central Europe: Interactions between surface anomalies at different scales and the dynamical implication . Quart. J. Roy. Meteor. Soc. , 144 , 2863 – 2875 , . 10.1002/qj.3415 Ben Bouallègue , Z. , and S. E. Theis , 2014 : Spatial techniques applied to precipitation ensemble forecasts: From verification results to probabilistic products . Meteor. Appl. , 21 , 922 – 929 , https

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Christian Euler, Michael Riemer, Tobias Kremer, and Elmar Schömer

. 2018 ). For our numerical simulation, COSMO is used in default settings: the heating rate due to radiation is calculated by the parameterization scheme of Ritter and Geleyn (1992) . Surface heat, moisture and momentum fluxes are parameterized by a turbulent kinetic energy-based surface transfer scheme formulated in conservative thermodynamic variables. While the parameterization of deep convection is turned off, a shallow convection scheme after Tiedtke (1989) is used. Microphysical processes

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Volkmar Wirth, Michael Riemer, Edmund K. M. Chang, and Olivia Martius

rotation and the sphericity of Earth [for an introductory-level text on Rossby waves see Rhines (2002) ]. Rossby waves are in distinct contrast to other types of waves such as gravity waves or sound waves, which rely on gravity or the compressibility of air, respectively, for their basic restoring mechanism. The atmospheric general circulation cannot be understood without reference to Rossby waves because they transfer energy, moisture, and momentum across large distances. This can generate

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Peter Vogel, Peter Knippertz, Andreas H. Fink, Andreas Schlueter, and Tilmann Gneiting

flatlands, where MCSs during boreal summer provide the bulk of the annual rainfall ( Mathon et al. 2002 ; Fink et al. 2006 ; Houze et al. 2015 ) and convergence lines in the boundary layer or soil moisture gradients at the kilometer scale can act as triggers for MCSs ( Lafore et al. 2017 ). Sahelian MCSs often take the form of meridionally elongated squall lines with sharp leading edges characterized by heavy rainfall. Synoptic-scale African easterly waves are known to be linked to squall

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