No, it is not snowing. No, it is not raining.
It is doing both at one time.
So what else would you call it?
You would think that snain would be relatively easy to drive on. Not so.
It is slick or slippery, depending on your preference. I guess we could call it slickery.
I guess the end result is :
Slow down folks, it is slickery out there because it is snaining.
PS. My spell check is going nuts!!!