when i saw this thread title, the first thing that came to mind was this severe warned MCS that come through one morning...i cant remember the day, but i know it was a pretty big event, and wasnt too long ago...
well, you know how lines are supposed to form 30 miles or so ahead of the front...well this one passed through about 530 in the morning, and after it done blew through or whatever, i come out side...it was cool, and still damp from the soaking rain, there was twigs and leaves out...and from that spot in the yard, you could look straight up and see the underside of the backsheared anvil...you could look straight east and still see lightning going on from the departing MCS...and you could look straight west and see a beautiful sunrise...
now what really tripped me out was, there was no clouds behind it (looking to the west) but there was this little fibrillated wave of clouds that just come creeping overhead, and then you could feel it...that little push of air, that i assume was the surface front...
at that point, i was at the intersection of a 1500+ mi squall line and a huge mass of air that was moving around the country...might not seem like much, but it was crazy...never will forget it!