 The winter storm is an event in which varieties of precipitation are formed that only occurred at low temperatures, such as snow or sleep, or a rainstorm where ground temperatures are low enough to allow ice to form IE freezing rain. In temperate continental climates, these storms are not necessarily restricted to the winter season, but may occur in the late autumn and early spring as well. Very rarely, they may form in summer, though it would have to be an abnormally cold summer, such as the summer of 1816 in the northeastern United States. Snow storms are storms where large amounts of snow fall. To inches 5 centimeters of snow is enough to create serious disruption 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 not typical but heavy accumulating snowfalls can occur. In places where snowfall is typical, such small snowfalls are rarely disruptive because of effective snow and ice removal by municipalities, increased use of four-wheel drive and snow tires, and drivers being more used to winter conditions. Snowfall in excess of 6 inches 15 centimeters are usually universally disruptive. The massive snow stormed with strong winds, and other conditions needing certain criteria is known as a blizzard. A large number of heavy snow storms, some of which were blizzards, occurred in the United States during 1888 and 1947 as well as the earlier in the 1990s. The snowfall of 1947 exceeded to feet 61 centimeters with drips and snow piles from plowing that reached 12 feet 3.7 meters and for months, temperatures did not rise high enough to melt the snow. The 1993 superstorm manifested as a blizzard in most of the affected areas. Large snow storms could be quite dangerous, a 6 in 15 centimeters snowstorm will make some unplowed roads impassable, and it is possible for automobiles to get stuck in the snow. Snowstorms exceeding 12 in 30 centimeters especially in southern or generally warm climates will cave the roofs of some homes and cause the loss of electricity. 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.