Translation:It may snow tomorrow.
There is no meaningful difference between 'might' and 'may' in common speak so both should be accepted.
Why is 周末可能下雨 (from another question: it may rain on the weekend) correct but in this case 明天可能下雪 is wrong
明天可能会下雪 is the only accepted answer for this question
"It might snow tomorrow" not accepted (although noted seven months ago). Reported 9th September 2018.