THE PILOT REPORTED HE WAS LANDING ON RUNWAY 16 WITH A CROSSWIND FROM 210 DEGREES AT 8 KNOTS, GUSTING TO 12. HE SAID HE WAS JUST TOUCHING DOWN ON 'PATCHY ICE' WHEN A GUST OF WIND BLEW THE AIRPLANE OFF THE RUNWAY. HE WAS UNABLE TO MAINTAIN DIRECTIONAL CONTROL, AND THE AIRPLANE WENT OFF THE RUNWAY AND NOSED OVER.