In 1991 and 2001, 8″ of snow fell the day or night before the Birkie (here’s the history). Since then, there has only been light snow before the race, although it has snowed with some frequency.
In 2013, we might get back to a Birkie Blizzard. A week out from the race, we have a whole suite of models showing a strong storm in the Midwest for the Birkie. Of course, things may change dramatically, but for now it looks like Birkieland would be near the northern edge of the snow. A southwards shift could leave the trail high and dry (although conditions are already primed for the race, so we don’t need the snow), and that is a possibility. However, a number of model runs have shown several inches of snow on Friday (which is less than a week away!) and overnight in to the morning on Saturday. Not that anyone really minds skiing in the snow.