Foehn warming mechanism and near-surface weather impact at the northern foreland of the Moravian-Silesian Beskids, Czech Republic

Abstract The interaction of large-scale flow and local topography can lead to various meteorological phenomena. A prominent example is foehn, a dry and warm leeward wind. Foehn’s impact on near-surface meteorological parameters and its formation mechanisms have been extensively studied in the Alps and other regions worldwide. However, less attention has been given to pronounced warm events in leeward areas of Central European mountain ranges with peak altitudes of 1100–1600 m asl. This paper investigates three selected foehn events induced by strong southerly flow over the Moravian-Silesian Beskids range in the northeastern part of the Czech Republic. The three foehn events from 31 October 2010, 14 January 2008, and 30 October 2021 represent situations with the highest 2 m temperature differences between Lučina (a foehn-affected region) and Olomouc (an unaffected region), reaching 12.8 °C in the first case and 10.8 °C in the two other cases. In addition to in-situ observations, these events were investigated using atmospheric cross-sections and backward-trajectory analyses based on Weather Research and Forecasting (WRF) model output. Finally, isentropic drawdown with a mean descent of trajectories by ~ 400–600 m was identified as the principal foehn warming mechanism, resulting in adiabatic warming and intense surface-layer mixing.