How an uncertain short-wave perturbation on the North Atlantic wave guide affects the forecast of an intense Mediterranean cyclone (Medicane Zorbas) ...

Mediterranean cyclogenesis is known to be frequently linked to ridge building over the North Atlantic and subsequent anticyclonic Rossby wave breaking over Europe. But understanding of how this linkage affects the medium-range forecast uncertainty of Mediterranean cyclones is limited, as previous pr...

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Bibliographic Details
Main Authors: Portmann, Raphael, González-Alemán, Juan Jesús, Sprenger, Michael, Wernli, Heini
Format: Article in Journal/Newspaper
Language:English
Published: ETH Zurich 2020
Subjects:
Online Access:https://dx.doi.org/10.3929/ethz-b-000456727
http://hdl.handle.net/20.500.11850/456727
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Summary:Mediterranean cyclogenesis is known to be frequently linked to ridge building over the North Atlantic and subsequent anticyclonic Rossby wave breaking over Europe. But understanding of how this linkage affects the medium-range forecast uncertainty of Mediterranean cyclones is limited, as previous predictability studies have mainly focused on the relatively rare cases of Mediterranean cyclogenesis preceded by upstream extratropical transition of tropical cyclones. This study exploits a European Centre for Medium-Range Weather Forecasts (ECMWF) operational ensemble forecast with an uncertain potential vorticity (PV) streamer position over the Mediterranean that, 3 d after initialization, resulted in an uncertain development of the Mediterranean tropical-like cyclone (Medicane) Zorbas in September 2018. Later initializations showed substantially lower forecast uncertainties over the Mediterranean. An ad hoc clustering of the ensemble members according to the PV streamer position in the Mediterranean is used to ... : Weather and Climate Dynamics, 1 (2) ...