This isn't related to the polar vortex splitting, this is the polar vortex that has split. This is a part of the cold air mass that normally sits on the North Pole, but on top of Spain. Normally the cold arctic air spins around the north pole stably because it is cold and low pressure in the northern hemisphere winter. Warm air intruded into it, destabilized it, and it spun out into lower latitudes with corresponding intrusions of equally hot temperatures elsewhere (Tibetan plateau https://twitter.com/extremetemps/status/1348693028022738951/...)