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Tobias Selz and George C. Craig

-resolution configuration deep convection is considered to be resolved and the model is run with only a parameterization for shallow convection. The present study is based on the COSMO-DE configuration, but with the domain enlarged to a size of about 7000 km by 4250 km (2481 × 1521 grid points), which covers several times the Rossby radius of deformation. Some minor changes to the model setup were necessary since we used Integrated Forecast System (IFS) analysis and forecasts from the European Centre for Medium

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Lars Wiegand, Arwen Twitchett, Cornelia Schwierz, and Peter Knippertz

might be crucial for the development of some real-world PV streamers. PV streamers are often connected to high-impact weather events. Poleward moisture transport east of PV streamers can lead to heavy precipitation and flooding (e.g., Tripoli et al. 2005 ; Knippertz and Martin 2005 , 2007a ). Studies centered on the European Alps ( Massacand et al. 1998 ; Fehlmann et al. 2000 ; Hoinka and Davies 2007 ) have concluded that heavy precipitation events are closely connected with elongated

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Andrea Schneidereit, Silke Schubert, Pavel Vargin, Frank Lunkeit, Xiuhua Zhu, Dieter H. W. Peters, and Klaus Fraedrich

its long persistence extending to mid-August is not ( Matsueda 2011 ). Thus, the question arises: what are the causes of this long-lasting heat wave or rather the blocking high? Blocking, in general, denotes the effect of a synoptic system acting as a barrier to the westerly flow splitting the jet stream ( Elliott and Smith 1949 ). The formation of a block over Europe can be ascribed to the convergence (or absorption) of wave activity density flux associated with an incoming anomalous quasi

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Yannick Barton, Paraskevi Giannakaki, Harald von Waldow, Clément Chevalier, Stephan Pfahl, and Olivia Martius

succession resulted in high-impact flood events are the severe floods in central Europe in summer 2013 ( Grams et al. 2014 ), the floods in Pakistan in summer 2010 ( Galarneau et al. 2012 ; Martius et al. 2013 ), and the floods in England in the winter 2014 ( Huntingford et al. 2014 ). Second, the short recovery time between events can overburden rescue teams and prevent proper clean-up of damages and efficient repairing of damaged protective structures. Moreover, the temporal clustering and hence

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Julia H. Keller, Sarah C. Jones, and Patrick A. Harr

increased midrange forecast uncertainty in Europe. Thus, the potential for high-impact weather by the reintensified ex-TC or another cyclone, developing farther downstream, often coincides with poor predictability, which enforces the possible impact of such an event. Reduced predictability can be linked, on the one hand, to a misrepresentation of the influence of the midlatitude flow on the TC, leading to errors in the forecast for structural changes within the TC ( Evans et al. 2006 ) and the

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Martin Weissmann, Florian Harnisch, Chun-Chieh Wu, Po-Hsiung Lin, Yoichiro Ohta, Koji Yamashita, Yeon-Hee Kim, Eun-Hee Jeon, Tetsuo Nakazawa, and Sim Aberson

to a single aircraft deployed through the Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR) program ( Wu et al. 2005 ). In autumn 2008, an international effort by several countries in North America, East Asia, and Europe was made to observe TCs in the western Pacific throughout their full life cycle from the genesis in the tropics until extratropical transition and the interaction with the midlatitude flow for the first time. These observations were conducted

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Andreas Schäfler, Andreas Dörnbrack, Christoph Kiemle, Stephan Rahm, and Martin Wirth

water vapor and the associated latent heat release are thought to be a major weakness in the formulation of current operational NWP models. The diagnosis of “forecast–analysis” differences of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) by Didone (2006) and Dirren et al. (2003) revealed characteristic patterns of forecast errors on the downstream side of the cold front of the extratropical cyclones. Among the observational errors of the initial

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Florian Harnisch and Martin Weissmann

collaboration with T-PARC, the Taiwanese Astra Jet was operated under the research program Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR), where dropsonde observations are deployed operationally on TCs that pose a threat to the Taiwanese island ( Wu et al. 2005 , 2007b ). This study investigates the benefit of T-PARC dropsonde observations in different locations on the basis of data denial experiments with the European Centre for Medium-Range Weather Forecasts (ECMWF

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Simon T. K. Lang, Sarah C. Jones, Martin Leutbecher, Melinda S. Peng, and Carolyn A. Reynolds

1. Introduction In the Ensemble Prediction System (EPS) of the European Centre for Medium-Range Weather Forecasts (ECMWF), singular vectors (SVs) are used to generate perturbations to the initial condition ( Leutbecher and Palmer 2008 ; Buizza et al. 2008 ). The rationale behind using SVs, the fastest-growing perturbations over a finite time interval, is to sample the dynamically most relevant structures that will dominate the uncertainty sometime in the future ( Ehrendorfer and Tribbia 1997

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Paraskevi Giannakaki and Olivia Martius

Europe results in significant errors in the forecasting of heavy precipitation in southern Switzerland. The focus of this study is on the model representation of one particular aspect of synoptic-scale Rossby waves, namely their waveguides. In the extratropics and subtropics, narrow and zonally extended areas of enhanced potential vorticity (PV) gradients, which are coaligned with the jet streams, act as waveguides for synoptic-scale Rossby waves (e.g., Schwierz et al. 2004 ; Martius et al. 2010

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