 An ice storm is a type of winter storm characterized by freezing rain, also known as a glaze event tour in some parts of the United States. As a silver thought, the U.S. National Weathered Service defines an ice storm as a storm, which results in the accumulation of at least 0.25 inch 6.4 mm of ice on exposed surfaces. From 1982 to 1994, ice storms were more common than blizzards in the U.S., averaging 16 per year. They are generally not violent storms, but, instead are commonly perceived as gentle rains occur in at temperatures just below freezing. Formation, the formation of ice, begins with a layer of above freezing air, above a layer of sub-freezing temperatures, closer to the surface. Frozen precipitation melts to rain while falling into the warm bare layer, and then, begins to re-freeze in the cold layer below. If the precipitate re-freezes while still in the air, it will land on the ground as sweet. Alternatively, the liquid droplets can continue to fall without freezing, passing through the cold air just above the surface. This thin layer of air, then, cools the rain to a temperature below freezing 0 degrees C or 32 degrees F. However, the drops themselves do not freeze, a phenomenon called supercooling or forming supercool drops. When the supercool drops strike ground for anything else below 0 degrees C or 32 degrees F, e.g. power lines, tree branches, aircraft, a layer of ice accumulates as the cold water drips off, forming a slowly thickening film of ice, and freezing rain. While meteorologists can predict when and where an ice storm will occur, some storms still occur with little or no warning. In the United States, most ice storms are in the northeastern part of the country, but damaging storms have occurred farther south. An ice storm in February 1994 resulted in tremendous ice accumulation, as far south as Mississippi, and caused reported damage in nine states. More timber was damaged, than that caused by Hurricane Camille. An ice storm in eastern Washington in November 1996 directly followed heavy snowfall. The combined weight of the snow and 25 to 37 millimeters 0.98 to 1.46 din of ice caused widespread damage, and was considered the most severe ice storm in the Spokane area since 1940.