THE PILOT LANDED AT NIGHT ON THE LEFT SIDE OF THE RUNWAY WITH A 19 KT CROSSWIND COMPONENT FROM THE LEFT. DURING THE LANDING ROLL, THE AIRPLANE BEGAN TO DRIFT LEFT TOWARD DRIFTING SNOW, AND SUDDENLY VEERED LEFT AND DEPARTED THE LEFT SIDE OF THE RUNWAY. THE RUNWAY WAS PLOWED IMMEDIATELY AFTER THE ACCIDENT. THE PILOT STATED HE HIT A SNOW DRIFT DURING LANDING.