Automated Severe Thunderstorm Oulooks from thundeR Package (ASTORP)

Construction of thunderstorm environmental datasets consisting of severe weather reports from 4 continents (Europe, Australia, North America, South America), global lightning detection data, SPC and ESTOFEX convective outlooks, and over 700 convective parameters derived from hybrid-sigma levels of global ERA5 reanalysis dataset allowed development of machine learning models aimed at predicting probability for the occurrence of non-severe, severe and significant severe convective storms. In the first step of model development, database was organized to choose the best environmental proxies for the identification of: (1) lightning occurrence given any environment, (2) severe hail occurrence given lightning, (3) severe tornado occurrence given lighting, (4) severe wind occurrence given lightning, (5) significant hail occurrence given severe hail, (6) significant tornado occurrence given severe tornado, and (7) significant wind occurrence given severe wind. In order to avoid biases towards certain geographical areas, the process of selecting best predictors for hail, tornadoes and wind have been performed separately for each continent and then best predictors contributing to final models were selected with the assumption that they should work on each evaluated domain. Among those parameters, a best combination (leading to highest skill) of 5-7 ingredients were selected for each model. In the second phase, models were used to produce historical convective outlooks consistent with SPC and ESTOFEX risk levels methodology for the period 2015-2023 and using ERA5 reanalysis. Based on those outlooks, a calibration process was performed to better fit modeled convective hazard risk probabilities. Since march 2025, a final calibrated models are used with operational GEFS for both Europe and the United States, producing convective outlooks 4x daily with a forecast up to 9 days. In this work we will present a methodology of constructing ASTORP models and show sample forecasts generated with those models and operational GEFS during spring and summer of 2025 for Europe and the United States.