Sounds generic, but if they can gather enough strength to hammer away at swords and shields, I'm pretty sure they can press their backs to snow. After all, they're elves. They might just consider it a work of art, and when they're done they'll stand up and say 'Whee! Snow art! Now let's rebuild Gondolin."
Though one thing did fox me:
"...and for running light over grass and
leaf, or over snow - an Elf." Unless, of course, he meant those tiny leaves that grow from the ground