<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Hail involving very large hailstones (maximum diameter ≥ 5 cm), is a rare but very hazardous phenomenon in Poland, and can be forecast using reflectivity signatures. Every year, Poland experiences from one to over a dozen storms with such large hailstones. Despite the current recommendations regarding polarimetric techniques used in hail risk monitoring, Poland does not have a fully polarimetric radar network. Therefore it is essential to check hail detection capabilities using only reflectivity techniques based on individual radar systems involving hail detection algorithms such as Waldvogel et al. (1979) or Vertically Integrated Liquid thresholds connected with manual signature analysis to get better warning decisions. This study is aimed to determine the reflectivity features, thresholds and lead times for nowcasting of severe storms with very large hailstones in Poland, using data from the Polish radar system and from the European Severe Weather Database for the period 2007–2015. Most incidents involving very large hailstones were linked to supercell storms with distinctive reflectivity signatures, however, some storms with extremely large hailstones presented very poorly developed signatures. These signatures enabled the prediction of hail involving very large hailstones approximately 29 minutes before it fell. The Lemon (1980) criterion and WER were found to be the best hail predictors for Polish radar system conditions.</p></abstract>

Hail involving very large hailstones (maximum diameter ≥ 5 cm), is a rare but very hazardous phenomenon in Poland, and can be forecast using reflectivity signatures. Every year, Poland experiences from one to over a dozen storms with such large hailstones. Despite the current recommendations regarding polarimetric techniques used in hail risk monitoring, Poland does not have a fully polarimetric radar network. Therefore it is essential to check hail detection capabilities using only reflectivity techniques based on individual radar systems involving hail detection algorithms such as Waldvogel et al. (1979) or Vertically Integrated Liquid thresholds connected with manual signature analysis to get better warning decisions. This study is aimed to determine the reflectivity features, thresholds and lead times for nowcasting of severe storms with very large hailstones in Poland, using data from the Polish radar system and from the European Severe Weather Database for the period 2007–2015. Most incidents involving very large hailstones were linked to supercell storms with distinctive reflectivity signatures, however, some storms with extremely large hailstones presented very poorly developed signatures. These signatures enabled the prediction of hail involving very large hailstones approximately 29 minutes before it fell. The Lemon (1980) criterion and WER were found to be the best hail predictors for Polish radar system conditions.

Radar reflectivity signatures and possible lead times of warnings for very large hail in Poland based on data from 2007-2015

Environmental & Socio-economic Studies

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Hail involving very large hailstones (maximum diameter ≥ 5 cm), is a rare but very hazardous phenomenon in Poland, and can be forecast using reflectivity...

Radar reflectivity signatures and possible lead times of warnings for very large hail in Poland based on data from 2007-2015

Published Online: Sep 08, 2020

Page range: 34 - 47

Received: Jun 20, 2020

Accepted: Aug 24, 2020

DOI: https://doi.org/10.2478/environ-2020-0016

Keywords
reflectivity signatures, meteorological radar, very large hailstones, lead time, Poland

© 2020 Wojciech Pilorz et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Radar reflectivity signatures and possible lead times of warnings for very large hail in Poland based on data from 2007-2015

Published Online: Sep 08, 2020

Page range: 34 - 47

Received: Jun 20, 2020

Accepted: Aug 24, 2020

DOI: https://doi.org/10.2478/environ-2020-0016

Keywordsreflectivity signatures, meteorological radar, very large hailstones, lead time, Poland

© 2020 Wojciech Pilorz et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
reflectivity signatures, meteorological radar, very large hailstones, lead time, Poland