
General Info:
Snowstorms are storms where large amounts of snow fall. Snow is less dense than liquid water, by a factor of approximately 10 at temperatures slightly below freezing, and even more at much colder temperatures. Therefore, an amount of water that would produce 2 cm (0.8 in.) of rain could produce as much as 20 cm (8 in.) of snow. Five centimeters of snow (2 in.) is enough to create serious disruptions to traffic and school transport (because of the difficulty to drive and maneuver the school buses on slick roads). This is particularly true in places where snowfall is uncommon but heavy accumulating snowfalls can happen (e.g., Atlanta, Seattle, London, Canberra, Vancouver). In places where snowfall is common, such as Utica, Detroit, Montreal, Quebec City, Toronto and Minneapolis, such small snowfalls are rarely disruptive, though snowfalls in excess of 15 cm (6 in.) usually are.
A massive snowstorm with strong winds and other conditions meeting certain criteria is known as a blizzard. A large number of heavy snowstorms, some of which were blizzards, occurred in the United States during the early and mid-1990s, and the 1993 "Superstorm" was manifest as a blizzard in most of the affected area.
Large snowstorms could be quite dangerous: a 15 cm (6 in.) snowstorm will make some unplowed roads impassible, and it is possible for automobiles to get stuck in the snow. Snowstorms exceeding 30 cm (12 in.) especially in southern or generally warm climates will cave the roofs of some homes and cause the loss of power. Standing dead trees can also be brought down by the weight of the snow, especially if it is wet or very dense. Even a few inches of dry snow can form drifts many feet high under windy conditions.
Snowstorms are usually considered less dangerous than ice storms. However, the snow brings secondary dangers. Mountain snowstorms can produce cornices and avalanches. An additional danger, following a snowy winter, is spring flooding if the snow melts suddenly due to a dramatic rise in air temperature. Deaths can occur from hypothermia, infections brought on by frostbite, car accidents due to slippery roads, fires or carbon monoxide poisoning due to alternative heating methods after a storm causes a power outage, or heart attacks caused by overexertion while shoveling heavy wet snow.
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