Snow 9999

I saw the first snowfall (of the year/this year) at the workplace (The First snowfall that I saw this year was at the workplace - your sentence is also correct, though I think that it doesn't put an appropriate emphasis on respective parts of the sentence). According to my mother, it's not snowing around my house /it wasn't snowing around my house though - if you had begun with a past simple you should have continued with it. The workplace is located at the foot of a mountain. I think that's(it puts a proper emphasis, noone would use it's in this case) why I could see the snowfall.
Thanks.