Dirty snow on roof by chimney

I noticed today after the storm there was some dirty brownish snow on the roof near the chimney is this normal?

You may have gotten some really strong drafts during the storm that pulled some loose stuff out.

Is the dark spot on the left near the roof edge a shadow or is that the discolorization?I get some brown drippings from mine once in a while..I just thought it was condensation dripping from letting it cool off .I'm watchin this one .

my friends have black creosote dripping out of their cap all down the chimney, but again they do like to burn that "green wood" That they just had to have me get for them so that they could split it and then burn it that very same day. They never get to far ahead so that it does not dry out?

I snapped this picture later on in the day after I finished snowblowing.The discoloration to the left was just a shadow but before more of the snow melted it was a brown stain on all the snow on the roof near the chimney.

Noticed the same thing over here