Lightning jump as a nowcast predictor: Application to severe weather events in Catalonia

• The adaptation and modification of a lightning jump identification algorithm is presented, based exclusively on the total lightning data.
• The lightning jump pattern has proven to be a good forecaster tool.
• The technique has been tested with 44 cases of severe weather (hail, tornadoes, and strong winds) in Catalonia.
• The lead time between the lightning jump identification and the observation of the severe weather phenomena has been of more or less 20 min in most of the analyzed cases.

Several studies reported sudden increases in the total lightning flash rate (intra-cloud+cloud-to-ground) preceding the occurrence of severe weather (large hail, wind gusts associated to thunderstorms and/or tornadoes). Named “Lightning Jump”, this pattern has demonstrated to be of operational applicability in the forecasting of severe weather phenomena. The present study introduces the application of a lightning jump algorithm, with an identification of cells based solely on total lightning data, revealing that there is no need of radar data to trigger severe weather warnings. The algorithm was validated by means of a dataset severe weather events occurred in Catalonia in the period 2009–2014. Results obtained revealed very promising.