I got back from snowboarding on Sunday and my car has been issuing a CEL. Is it common for a Subaru that's been through snow to issue CELs? If so, what's the reason?

You can go to advance or your auto parts store and borrow an OBDII reader. Plug it into your car and you can read the code to truly find out the reason.

I don't know what the reason is, unless maybe your front end was packed with snow along the grill and radiator, which suffocated your car.

If the Subaru isn't properly clamped into the board's bindings, you can damage the alignment. ;)

More seriously, sometimes snow can get packed into the wheel wells and mechanically obstruct things, but the code readout should point you in the right direction.

I figured out that it may have been crappy gas that I was forced to buy from a gas station out in the boonies. The CEL went away two days later. A fellow friend is pulling the code from the ecu for me. What code should I expect if it really is the bad gas (I already promptly filled up with good gas once I remember the crappy gas was used).

The code pulled from the ECU was a p0303: misfiring in cylinder #3. I guess the crappy gas caused a knock in cylinder 3, which is expected because cylinder 3 is closest to the turbo and gets the most heat and therefore is the first to have detonation before the other cylinders.