Graphical Abstract

Tochimoto, E., and H. Niino, 2018: Structure and environment of tornado-spawning extratropical cyclones around Japan. J. Meteor. Soc. Japan, 96, 355-380.
https://doi.org/10.2151/jmsj.2018-043 Graphical Abstract with highlights

This study used the JRA-55 reanalysis dataset to analyze the structure and environment of extratropical cyclones (ECs) that spawned tornadoes (tornadic ECs: TECs) between 1961 and 2011 in Japan.
Our comparison of the structures and environmental parameters of TECs and non-tornadic ECs (NTECs) in each season indicates that CAPE for TECs in all seasons is larger than that for NTECs. Thus, thermodynamically more unstable environments seem to be important for tornado occurrences.
A comparison of TECs between Japan and the United States (US) shows that SREH and CAPE are noticeably larger in the US. It is suggested that these differences occur because TECs in the US (Japan) develop over land (ocean), which exerts more (less) surface friction and diurnal heating.