One of the May 31, 1985 tornadoes is a pretty good example of this too...
Although there were numerous other tornadoes that day across the lower lakes, probably the most intense tornado was the one that ripped across the Moshannon State Forest in Pennsylvania. This one cut a continuous 69 mile long, 2.2 mile wide path of F4 intensity through the ranges and deep forests of the Allegheny Mountains. If I remember correctly it was on the ground for about an hour and a half...
Nobody may have seen the tornado itself however, as it remarkably enough, stayed out to wilderness for nearly it's entire path. It obliterated about 85,000 trees, and even crossed the west branch of the Susquehenna River, twice! The aerial survey of the tornado (although I wasn't able to find any actual photos), showed that it virtually clear-cut the forest right to the ground, apparently. And, yes -- it even crossed some mountains that were in some cases up to 2000 feet high (I don't recall the exact names though).
Interestingly, the tornado ripped up so many trees that it was actually visible on radar, kind of like the Moore tornado of 1999 (quote from the Pittsburgh Post-Gazette):
"Even the meteorologists were transfixed. Greg Forbes, The Weather Channel's severe weather expert, was a professor of meteorology at Penn State in May 1985. On radar, he watched, riveted, as an F-4 tornado moved through Moshannon State Forest, across Clearfield, Clinton and Centre counties, sucking up so many trees that the debris could actually be seen on the screen as a little round ball in the center of a hook-shaped radar "echo" -- the mark of a tornado. Using the reverse terminology peculiar to meteorologists, Forbes described it "as one of the best radar signatures I've ever seen."
A couple of links --
http://www.angelfire.com/pa/pawx/053185.html
http://www.post-gazette.com/pg/05149/511826.stm
Eric
