A 10-year climatology of cold-season narrow cold-frontal rainbands in Germany

Environmental conditions that can support deep moist convection during the cold season are analyzed using a 10-year climatology of narrow cold-frontal rainbands (NCFRs) in Germany. One hundred twenty events were detected. Mid-level processes seem to be an important indicator for the development of deep moist convection: a majority of the detected NCFRs developed at the cyclonically sheared side of strong mid-level jet streaks where also lightning and severe weather occurrence were concentrated. The thermodynamic environment along the NCFRs is analyzed using more than 50 proximity soundings. Very weak instability, strong low-level vertical wind shear, and indications of the presence of moist absolutely unstable layers were found. CAPE was not a good indicator to discriminate between electrified and non-electrified events. A relationship between the occurrence of low-level mixing and severe wind gusts was not found. The high fraction of missed events in the Estofex forecasts indicates that this type of convection is difficult to forecast.