In Switzerland, hailstorms are one of the costliest damaging natural catastrophes. Furthermore, the complex topography, the available high quality radar measurements of MeteoSwiss, the location in central Europe and the previous research done in this field makes this location an ideal laboratory for hail research. With today’s data and recently developed modeling methods, there is great potential in improving the hail prediction in Switzerland. This work aims to improve the prediction of hail, so that the possibility of preventive measures is increased and the impact of hail is reduced.

In the first part of my PhD I analysed >50'000 crowd-sourced hail reports, that were submitted by the population in Switzerland via MeteoSwiss Weather App. After filtering the reports for credibility, I compared the reported hail size to the values given by the two radar-based hail algorithms POH (probability of hail) and MESHS (maximum expected severe hail size).

Currently, I am using the crowd-sourced reports to train machine learning models, which should determine which atmospheric variable is most useful to nowcast hail. With this analysis we will try to uncover regional differences in hail producing environments and determine how we can improve current hail predictions.

More about ongoing projects on hail at the Mobiliar Lab for Natural Risks.

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Barras, Hélène; Hering, Alessandro; Martynov, Andrey; Noti, Pascal-Andreas; Germann, Urs; Martius, Olivia (2019). Experiences with >50,000 Crowdsourced Hail Reports in Switzerland. Bulletin of the American Meteorological Society, 100(8), pp. 1429-1440. American Meteorological Society 10.1175/BAMS-D-18-0090.1


Trefalt, Simona Esther; Martynov, Andrey; Barras, Hélène; Besic, Nikola; Hering, Alessandro M.; Lenggenhager, Sina; Noti, Pascal; Röthlisberger, Matthias; Schemm, Sebastian; Germann, Urs; Martius, Olivia (2018). A severe hail storm in complex topography in Switzerland - Observations and processes. Atmospheric research, 209, pp. 76-94. Elsevier 10.1016/j.atmosres.2018.03.007


Mobiliar Lab Herbstveranstaltung: Hagel-Pionierland Schweiz - innovative Projekte für die Praxis, Bern, 13/11/2019
Der Beitrag der Öffentlichkeit zur Hagelprognose, oral presentation

European Conference on Severe Storms, Krakow, 04-08/11/2019
Improving hail nowcasting by combining crowd-sourced hail reports with machine learning, oral presentation
Using >60'000 crowd-sourced hail reports for the verification of radar based hail products, poster

Seamless Forecasting Workshop, Locarno Monti, Switzerland, 02-04/09/2019
Swarm intelligence - Understanding and using hail crowdsourcing information, oral presentation

EGU General Assembly 2019, Vienna, Austria, 08-12/04/2019
Experiences with >50’000 crowd-sourced hail reports in Switzerland, oral presentation

1st Swiss Workshop on Machine Learning for Environmental and Geosciences (MLEG), Dübendorf, Switzerland, 16-17/01/2019


17th Swiss Climate Summer School, Grindelwald, Switzerland, 26-31/08/2018
Using >50'000 crowdsourced hail reports for the verification of radar based hail products in Switzerland, poster

2018 North American Workshop on Hail and Hailstorms, Boulder, CO, USA, 14-16/08/2018
Using >50'000 Crowdsourced Hail Reports for the Verification of Radar Based Hail Products, oral presentation

SGHL Tagung: Citizen Science – Gemeinsam forschen und lernen in Hydrologie und Limnologie, Zürich, 11/06/2018
Citizen Science Daten für die Schweizer Hagelforschung und ein neues kollektives Überschwemmungsgedächtnis, oral presentation (invited)

EGU General Assembly 2018, Vienna, Austria, 09-13/04/2018
The verification of radar hail detection algorithms using >50’000 crowd-sourced hail reports in Switzerland, pico presentation


2nd European Hail Workshop, Bern, Switzerland, 19-21/04/2017

COSMO User Workshop 2017, Zurich, 20/01/2017
Verification of strong wind gusts in COSMO-2, oral presentation


Hans Sigrist Symposium 2016, Bern, 02/12/2016

17th Swiss Global Change Day, Bern, 12/04/2016
Verification of strong wind gusts in COSMO-2, poster

COSMO User Workshop 2016, Zurich, 18/01/2016
Verification of extreme wind gusts in COSMO-2, oral presentation


Bicentenary of the great Tambora eruption, Bern, 07-11/04/2015