How did the sun manage to melt the snow on a day where it was 17 degrees out?

The sun caused the snow to evaporate.

The Sun melts the snow when it is 50 degrees below zero.  All that is needed is a little dust or dirt in the snow to absorb the Sun's heat.  On the northern prairie of the Great Plains, the cold wind will form huge ice windows where the snow below melts.  Then you will see spiders , insects and sometimes little flowers under the window.  People keep big cans of dry dirt to spread on icy sidewalks.  It will melt the ice when it is far below zero.

On any day well below freezing, the Sun light is absorbed by, and heats anything, darker than snow.  Sidewalk, pavement, field, lawn, trees, roof  and even snow with dirt particles.  That heat melts the snow.  People still keep a can of dirt in the garage to throw on icy sidewalks.

Just because the air temperature is 17, doesn't mean that all objects in the air need to be 17, also.  For example, if your face is exposed on a day like that, your face couldn't all be 17, because then it would be frozen solid.  The air layer right next to your face would be warmer than 17.  And if you faced the sun, your face would feel just a little warmer, showing that the sun can add energy even on a cold day.

That said, 17 is pretty cold, and it would have to be a very wind-sheltered area for snow to melt.  It would help if the snow was dirty, too, as dark colors reflect less of the sun's heat.

(assuming Farenheit scale for this answer)

thermonuclear energy . 

impurities in the snow lower the melting-point

I have no idea how warm or cold 17 degrees fahrenheit is

The air temperature rises and falls due to a combination of wind, sunshine and cloud cover. As the sun emerges in the morning it's energy warms the air causing the temperature to rise. Even when the temperature of the air doesn't reach 32° the sun can still warm the ground, snow, dirt, homes, etc. to 32°. When that happens the snow or ice will still melt even if the air temperature doesn't reach freezing.

Some of the snow sublimates directly to vapor . if the?Sun shines on it long enough some of it may melt, but not much. Central Oklahoma still has snow where the Sun doesn't shine for very long and we've been above freezing during the day for 3 days and above freezing for over 40 hours. It got to 62° F today. I didn't put on a sweater when I went to get my mail. I should have worn a sweater. 

Can because it heats it up like I know that driving down through the Virginia snow storm on 85 ice melted and fell off of the road signs above my car and hit my car completely cracked it here there and everywhere so yeah      it's weird but it's true