The European model is shown above, projecting temperature anomalies 5000 feet off the ground for the morning of May 14th. A large swath of well below-normal temperatures is seen swinging into the northern Plains, Midwest and Northeast. It does appear that this outbreak would occur following the passage of a storm system across southern Canada, which is the typical way an arctic cold event transpires. This outbreak is not yet showing up on the American GFS modeling system, and is only shakily supported by the ECMWF model and its ensemble set. That said, the synoptic set-up isn't all that impossible.