I think you're mis-viewing the scene. 

 - Elsa uses her powers to make a snow flurry appear in mid-air
 - She then uses the "sweep crossed hands" gesture (otherwise known as the "[no good gesture][1]") to cancels the power holding the flake up, which makes the ice crystals fall out of the air.

There's no particular evidence to suggest that she's *thawed them* when they drop and when we see behind her (a few seconds later) the snow seems unblemished


  [1]: http://adayinthewife.com/wp-content/uploads/2013/11/arms-crossed.jpg