Using lidar (analogous to radar, with pulses of laser light standing in for radio waves), Phoenix picked up signs of snow drifting down from clouds some 2.5 miles (four kilometers) overhead. It has not been seen reaching the Martian surface; it appears to vaporize before landfall.
"Nothing like this view has ever been seen on Mars," James Whiteway of York University in Toronto said in a statement. Whiteway is lead scientist for Phoenix's Meteorological Station (MET), the Canadian Space Agency's contribution to the mission. He added that the MET team will now seek to discover "signs that the snow may even reach the ground."
The Martian winter is approaching, and soon there will be inadequate sunlight to power the lander. Link