WINONA, Minn. — For five months Winona police have used their annual statutory authority to enforce alternate-side winter parking requirements. But under Municipal Ordinance 61.56, alternate-side parking ends March 15 — Sunday — the same day as a major snow storm is expected. The latest forecast:14 to 17 inches and possibly a blizzard. So what to do? Mike Biggerstaff, city streets supervisor, is asking citizens to abide voluntarily by the winter ordinance a few extra days so plow crew can clear streets for emergency vehicles to get where they need to get.