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Stephan Rasp and Sebastian Lerch

1. Introduction Numerical weather prediction based on physical models of the atmosphere has improved continuously since its inception more than four decades ago ( Bauer et al. 2015 ). In particular, the emergence of ensemble forecasts—simulations with varying initial conditions and/or model physics—added another dimension by quantifying the flow-dependent uncertainty. Yet despite these advances the raw forecasts continue to exhibit systematic errors that need to be corrected using statistical

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

1. Introduction Convection-permitting numerical weather prediction (NWP) models underpin a step change for operational forecasting centers in their struggle to predict thunderstorms and convective precipitation ( Clark et al. 2016 ) as they allow some key issues to be addressed. First, the intrinsically limited predictability of the small scales, including convection, necessitates the use of ensembles to generate probabilistic forecasts and assess their confidence ( Lorenz 1969 ; Slingo and

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Marlene Baumgart, Michael Riemer, Volkmar Wirth, Franziska Teubler, and Simon T. K. Lang

1. Introduction Numerical weather prediction has improved remarkably over the last decades (e.g., Bauer et al. 2015 ). Occasionally, however, very poor medium-range forecasts do still occur ( Rodwell et al. 2013 ). Forecast errors arise due to errors in the initial conditions and due to model deficiencies (e.g., Palmer and Hagedorn 2006 ). After 1–2 forecast days, localized errors may form that start to affect the synoptic-scale flow (e.g., Davies and Didone 2013 ; Martínez-Alvarado et al

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

1. Introduction Numerical weather prediction (NWP) has steadily improved over the last decades, allowing a multitude of socioeconomic benefits to be realized ( Bauer et al. 2015 ; Alley et al. 2019 ). While progress is unmistakable for 500-hPa geopotential heights and mean sea level pressure in the extratropics, improvements in the predictions of many other parameters are more variable ( Navascués et al. 2013 ). For example, forecasts of European cloud cover have hardly improved over the last

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

1. Introduction The bulk of precipitation in the tropics is related to moist convection, in contrast to the frontal-dominated extratropics. Because of the small-scale processes involved in the triggering and growth of convective systems, quantitative precipitation forecasts are known to have overall poorer levels of skill in tropical latitudes ( Haiden et al. 2012 ). This can be monitored in quasi–real time via the World Meteorological Organization (WMO) Lead Centre on Verification of Ensemble

Open access
Roderick van der Linden, Andreas H. Fink, Joaquim G. Pinto, and Tan Phan-Van

with thin, dashed lines. The orange dot denotes the location of the center of the ECMWF grid box that was used in the evaluation of the ensemble forecast (cf. Fig. 11 ). The green dot indicates the location of the Phu Lien radar station, and the blue dots denote the locations of the Bach Long Vy (WMO station ID 48839) and Beihai (WMO station ID 59644) radiosonde stations. According to D.-Q. Nguyen et al. (2014) , northeastern Vietnam can be separated into two distinct climate zones, termed N2 and

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Tobias Selz

1. Introduction Forecast skill has improved continuously over the last 40 years. The rate of improvement reached about one forecast day per decade, which means that a 6-day forecast today is as good as a 5-day forecast was 10 years ago. This considerable improvement together with its high socioeconomic impact has been recognized as a “quiet revolution” by Bauer et al. (2015) . However, such studies of past successes immediately raise the question of how far this progress will go on in the

Open access
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

transitioning cyclone (encircled during extratropical stage) and the “L” the position of the downstream cyclone. Together with Part I , this review describes developments in our understanding of ET since the first ET review by Jones et al. (2003 , hereafter J2003 ). The review by J2003 was motivated by the challenges that ET typically poses to forecasters in terms of predicting the structural evolution of the transitioning cyclone itself, and the high-impact weather that might be associated with it

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

conditions have been taken from archived operational analysis from the European Centre for Medium-Range Weather Forecasts. The simulation employs rotated spherical coordinates ( Doms and Schättler 2002 ), with the model equator running approximately through the center of the domain at 35°N. This rotation of the coordinate system minimizes the convergence of the meridians such that the grid spacing, specified in degrees latitude and longitude, is approximately constant. The results will be presented in

Open access
Marlene Baumgart, Paolo Ghinassi, Volkmar Wirth, Tobias Selz, George C. Craig, and Michael Riemer

1. Introduction Weather prediction has improved significantly in the past decades ( Bauer et al. 2015 ). Forecast dropouts, however, do still occur in operational numerical weather prediction models ( Rodwell et al. 2013 , 2018 ). Because of the multiscale nature of atmospheric dynamics, there may always be an intrinsic limit of predictability even if model errors and initial-condition errors occur only on the smallest resolved scale ( Lorenz 1969 ). Small-scale errors associated with moist

Open access