That happened to me going to Spain last year, 18"+ that same day and to my surprise we made it to the airport on time and the flight was on time too.
Tomorrow it's supposed to snow here, I have a 7 am flight, gotta be at the airport by 5 and I'm leaving the house by 3:30, the airport is 45 minutes away but I am giving myself extra time just in case, I'd rather wait at the airport than at home!