Either way it is very simple stuff, pointing towards storm centres or leading off from volcano chambers. (It is a lot easier to read than the damned EFS charts.)
Foolishly. I had no that idea I have been looking at the cold fronts hitting Europe without realising that a storm stepping onto a continental shelf is a signal like those leaving North America.
Whilst the latter ones (leaving North America) lead in some, as yet unknown specific, to the Aleutians; the cold fronts over the Atlantic, striking Western Europe, just as obvious.
Presumably there is a relationship to something of this nature:
and the current tornadic cell building in the Mid Atlantic at the moment:
