Is this possibly related to the strong weather that has been moving
through the midwest (and is due to hit here on the E Coast tonight)? Or
is it just a sign of the end of Winter MW propogation?

Good question-- my state (Minnesota) was on the northern edge of that storm
path, and the storm has passed well to our east now. I'll do some checking
around on the MW broadcast band after it gets dark here (around 6:50 local
time) and report back if I can't hear the usual stalwarts from the Midwest
and South, or if I hear stations that usually don't come in to my area.

Jackie