I have seen many April winter weather events (Quick 3 of the top of my head ... Major Ice followed by 7" of snow April 2003, 15" April 2005 and 9" April 2009). It is common to see flakes fly into early May in MBY. I always warn people who get excited about an early April warm up and tell them: "Do not to forget they live in MI. Let's get to May 10th and then we should be safe from snow until October. If we are lucky we will be done with snow well before May 10th."