Only time will tell for certain, but I for one believe our jet stream is being modified by the melting ice caps. A quote from a local weather caster:
"Larger undulations in the jet stream mean bigger dips and bigger crests. In the case of the polar vortex, a particularly deep trough allowed for very cold air masses to travel much further south than normal."
This I believe is the reason we're seeing the Midwest in a deep(er) freeze cycle the last few winters. The Alberta clipper is no longer flatting out, but dipping all the way down to Texas.
What has been noted on this snowbird forum the last few winters may be the new normal for Texas snowbirds.