Looking on the internet deeply has found these results:

it has been snowing since this morning. is the most popular phrase on the web.

it has been snowy since this morning. 10 results on the web	it has been snowing since this morning. 116 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	Nov 29, 2014 ... There was supposed to be a chimney cleaner coming too but it has been snowing since this morning and it was too slippery. Chunk was in the�... Dec 10, 2013 ... It has been snowing since this morning and there are a few flakes still floating around out there. My car did not like driving on the slippery roads�... Inky: It has been snowing since this morning and the mountain across the way looks as if it's been dusted with confectioner's sugar. It's just the beginning�... Mar 1, 2009 ... Plus, it has been snowing since this morning and still is snowing!! Inspired to have playlist of Bollywood songs in the snow. The sad thing is I�...

it has been snowy since this morning.

10 results on the web

it has been snowing since this morning.

116 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

Nov 29, 2014 ... There was supposed to be a chimney cleaner coming too but it has been snowing since this morning and it was too slippery. Chunk was in the�...
Dec 10, 2013 ... It has been snowing since this morning and there are a few flakes still floating around out there. My car did not like driving on the slippery roads�...
Inky: It has been snowing since this morning and the mountain across the way looks as if it's been dusted with confectioner's sugar. It's just the beginning�...
Mar 1, 2009 ... Plus, it has been snowing since this morning and still is snowing!! Inspired to have playlist of Bollywood songs in the snow. The sad thing is I�...