Hello all.

I am attempting to create a welcome message for my company's Spiceworks user portal which displays a message based on the date (used for holidays or other important dates). I have a script which does just that, but only for static dates (December 25, July 4, September 11). I would like to know how to do the same for the more complex holidays (Thanksgiving is the fourth Thursday in November, for example), but I can't figure out how to do so. Here is the code which I use currently to point out important dates:

Would anyone be so kind as to point me in the right direction? Thanks!