Resumen de The Lightning Jump, the 2018 ”Picking up Hailstones” Campaign and a Climatological Analysis for Catalonia for the 2006-2018 Period

Carme Farnell Barqué, Tomeu Rigo

• Previous analysis in Catalonia (NE Iberian Peninsula) demonstrated the high correlation between Lightning Jump (LJ) algorithm warnings and the occurrence of severe weather.

  The algorithm was put into operations in the Servei Meteorologic de Catalunya (SMC) ` (Meteorological Service of Catalonia) in 2016, exclusively considering lightning data. We found that more than 80% of the alerts were associated with at least one severe weather register in the area of study. This percentage could be even higher because of the lack of observations in some events that occurred in low-density population areas or at night. To collect surface registers that improve the information associated with the phenomena that occurred in severe thunderstorms in 2017, we started a citizen campaign (called ”Plega la pedra”, translated as ”Picking up Hailstones” using social networks (mainly, twitter -#meteocatpedra- and a WhatsApp channel).

  Thanks to the high contribution of the citizen campaign, the number of registers were higher than the average in comparable situations for previous years. The first part of this paper shows how it is functioning in the SMC, and the campaign results reported during 2018. The second part of the analysis consisted of a complete climatological study of its behavior in Catalonia, based on 13 years of data related to LJ alerts available. The study considered some characteristics such as the lead time, or the spatial, the monthly and yearly distributions. These features were compared and matched to severe weather observations recorded during this period in the same area. This analysis can help us to better understand the thunderstorms which triggered the warnings and the relationship between the alert and the severe weather observations on the surface.