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Hybrid Prediction of Weekly Tornado Activity Out to Week 3: Utilizing Weather Regimes

Tornadoes are one of the high‐impact weather phenomena that can induce life loss and property damage. Here, we investigate the relationship between large‐scale weather regimes and tornado occurrence in boreal spring. Results show that weather regimes strongly modulate the probability of tornado occurrence in the United States due to changes in shear and convective available potential energy and that persisting weather regimes (lasting ≥3 days) contribute to greater than 70% of outbreak days (days with ≥10 tornadoes). A hybrid model based on the weather regime frequency predicted by a numerical model is developed to predict above/below normal weekly tornado activity and has skill better than climatology out to Week 3. The hybrid model can be applied to real‐time forecasting and aide in mitigation of severe weather events.