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

extratropical cyclone . J. Atmos. Sci. , 74 , 1403 – 1416 , https://doi.org/10.1175/JAS-D-16-0260.1 . 10.1175/JAS-D-16-0260.1 Davis , C. A. , S. C. Jones , and M. Riemer , 2008 : Hurricane vortex dynamics during Atlantic extratropical transition . J. Atmos. Sci. , 65 , 714 – 736 , https://doi.org/10.1175/2007JAS2488.1 . 10.1175/2007JAS2488.1 Doms , G. , and U. Schättler , 2002 : A description of the nonhydrostatic Regional Model LM. Part I: Dynamics and numerics. Consortium for Small

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Stephan Rasp, Tobias Selz, and George C. Craig

convective motions are not excluded in principle. They are, however, indirectly excluded by the coarse resolutions and the long output time intervals that previous studies on WCBs have used. In addition, the convection parameterization scheme required at these resolutions directly introduces latent heat into the sounding based on closure assumptions to represent the effects of nonresolved vertical motions and thus hides them from the resolved flow. Not surprisingly a high sensitivity of the relative

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Stephan Rasp, Tobias Selz, and George C. Craig

Germany at 50°N, 10°E. For the analysis, a 256 × 256 gridpoint subdomain, roughly 717 km × 717 km, at the center of the simulation domain is considered to avoid boundary spinup effects. The 50-member ensemble simulations are started at 0000 UTC on each of the 12 consecutive days (see section 3 ) with a simulation time of 24 h. For initial and boundary conditions, we use hourly interpolated deterministic COSMO European version (COSMO-EU) analyses, which have a horizontal resolution of 7 km. Each

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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

forecast uncertainty is the representation of diabatic processes in NWP models. The convective parameterization schemes employed in all global models, and in some regional models, might underrepresent divergent outflow aloft, in part because the divergent outflow is a gridscale response to resolved precipitation processes, as well as parameterized convective heating and moistening ( Zadra et al. 2018 ). This error in the representation of diabatic processes affects the correct simulation of initial

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Jacopo Riboldi, Christian M. Grams, Michael Riemer, and Heather M. Archambault

of strong PV gradient in ACCEL, indicating that the trough keeps moving eastward, and a much weaker negative PV advection is present downstream, suggesting weaker ridge building ( Fig. 13j ). f. Far-downstream effects: Atmospheric blocking It has been shown that the presence of TC–trough interactions is associated with an increased likelihood over the North Pacific (see section 3a ). However, this response is also strongly modulated by the occurrence of phase locking. A large part of the

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

the initialization time. We employ the regional approach with a rolling training period of days, which yields superior results, consistent with the literature (e.g., Thorarinsdottir and Gneiting 2010 ). As shown in Figs. S2 – S5 in the supplementary material, our findings are insensitive to the choice of n when using training periods between 20 and 50 days. The local approach requires longer training periods and (in experiments not shown here) yields very similar results then. For EMOS

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

conservation of mass and circulation within a PV isoline on an isentropic surface. The computation of the MLM results in a stronger background flow than the climatological time average and, hence, stronger PV gradients. If one transcends linear theory and accounts for nonlinear effects, the waves do have an impact on the background state. In practice it may, therefore, be an advantage to use a nonstationary background flow, which implicitly accounts for the feedback of the waves on the waveguide. For

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

: Topographic effects on the eastward propagation and initiation of the Madden–Julian oscillation . J. Climate , 18 , 795 – 809 , https://doi.org/10.1175/JCLI-3292.1 . 10.1175/JCLI-3292.1 Huang , P. , and R. Huang , 2011 : Climatology and interannual variability of convectively coupled equatorial waves activity . J. Climate , 24 , 4451 – 4465 , https://doi.org/10.1175/2011JCLI4021.1 . 10.1175/2011JCLI4021.1 Huffman , G. J. , and Coauthors , 2007 : The TRMM Multisatellite Precipitation

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Andreas Schlueter, Andreas H. Fink, and Peter Knippertz

. 2009 ). Moisture anomalies starting at low levels, rise to midlevels prior to the convective peak. A stratiform moist outflow is left behind after the passage of the deep convection. In addition to adiabatic heating associated with the vertical circulation, diabatic effects create heating that slows down the wave. The reader is referred to Kiladis et al. (2009) for a more detailed review of the theory, observational evidence, and properties of CCEWs. Two additional disturbances dominate rainfall

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Thomas Engel, Andreas H. Fink, Peter Knippertz, Gregor Pante, and Jan Bliefernicht

, Animation A2 ) and the fact that the development took place around the secondary early morning rainfall peak ( Sane et al. 2012 ) suggest that the land–sea breeze in the Cape Verde area contributed to the enhancement of convection and recurrent new cell generation. However, although the rain event was the most severe at the Dakar-Yoff station, its physical causes appear to be a coincidental combination of effects that are each frequently observable there. Fig . 8. As in Fig. 4 , but for the Dakar flood

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