Evaluation of tornadic environments and their trends and projected changes in Japan

Tornadoes cause high-impact weather disasters in Japan, yet historical changes and future projections remain unclear. Using pseudo-soundings from high-resolution ERA5 reanalysis, the study evaluates environmental discriminators for F2+ tornadoes, including thermodynamic (CAPE, CIN, LCL, K-index), kinematic (BWD, SRH), and multivariate indices (EHI, KHI, STP). F2+ tornadoes occur with higher instability and helicity and are better distinguished by multivariate indices. Recent decades show significant regional increases in F2+ environments. A large-ensemble +2 K warming experiment indicates robust future increases in environments favorable for strong tornadoes, especially along the Sea of Japan and in Kanto. Despite projected decreases in BWD and increases in CIN, enhanced instability compensates, yielding more days with F2+ tornado potential.