Maine’s two biggest mountains normally don’t blow snow in April, but this hasn’t been a typical year. Tuesday, with temperatures starting in the single digits, both Sunday River and Sugarloaf ski areas were making snow. Last week they were the only two mountains in Maine still open. This weekend, Big Rock in Marsh Hill also is expected to reopen. In the 42 years Sugarloaf has made snow, it has never done so in April.