Great Lakes Mesoscale convective complexs or MCCs can cause damage to wide swaths of forest and shatter glass in city buildings. These storms mainly occur during the night, and the systems sometimes have small embedded tornadoes, but more often straight-line winds accompanied by intense lightning. Historically, the Great Lakes, in addition to their lake ecology, were surrounded by various forest ecoregions (except in a relatively small area of southeast Lake Michigan where savanna or prairie occasionally intruded). Logging, urbanization, and agriculture uses have changed that relationship. In the early 21st century, Lake Superior's shores are 91% forested, Lake Huron 68%, Lake Ontario
Great Lakes on Lake Ontario's northeast shore. Related to the lake effect is the regular occurrence of fog over medium-sized areas, particularly along the shorelines of the lakes. This is most noticeable along Lake Superior's shores. The Great Lakes have been observed to help intensify storms, such as Hurricane Hazel in 1954, and the 2011 Goderich, Ontario tornado, which moved onshore as a tornadic waterspout. In 1996 a rare tropical or subtropical storm was observed forming in Lake Huron, dubbed the 1996 Lake Huron cyclone. Rather large severe thunderstorms covering wide areas are well known in the Great Lakes during mid-summer; these