It is definitely NOT sleet. It is NOT hail. It’s kind of a soft spherical pellet (like hail, but soft) and it causes huge avalanche danger in the mountains. It is not a hip, new word — it’s been around at least 130 years. See my post above.
Looks like sleet to me.
It seems like an example of people who are snobbish about European things, they want to introduce a sophisticated European word to show their greater knowledge.