Can this last?

First thing this morning on the way out to the office, the contrast between the gradually melting roof snow and the brilliant blue of the sky was almost impossible to ignore. Could it last? Well for a couple of hours before it clouded over (the snow, of course, could and did) and then in mid-afternoon there was a very brief, but very heavy flurry of falling snow. It probably lasted all of a minute and began melting 30 seconds later! Where did that come from?