Arctic warming is altering the heat balance between the North Pole and the equator, which is what drives the strong current of upper level winds in the northern hemisphere commonly known as the jet stream. (salon.com)
Strong upper level winds provided support for supercell thunderstorms, which are thunderstorms that have persistent rotation associated with them, and can cause tornadoes and damaging large hail. (climatecentral.org)
Climatology was aware of this decades ago as it became aware of changing variability, especially of mid-latitude weather, with changes in upper level winds. (drtimball.com)