It's gone down a liitle to -5F and a windchill of of -42F. Exposed flesh can freeze in 4 - 5 minutes at these temps. It's a good day for playing cards in your underground house
Mt Washington is less than 6300 feet I think - it's just that it's in the way of weather systems from the north pole and the jet stream occasionally lowers to just a couple of thousand feet above the summit dragging all sorts of active weather with it.
(I worked outdoors a few times in emergency situations with wind chills of -30F and it was rough.) Eastern North America has worse weather than the west because Arctic air flows from the north west. In North Carolina, there are weather stations on Grandfather mountain and Mount Mitchell[a state park at 6600 feet]the highest mountain in the east and a few times a year, the winds blow in excess of 100 mph for hours.)