Introduction

Ice Storms are very remarkable and fascinating environmental events.  Many factors must be just so in order for these amazing natural occurrences to form.  Air temperature, pressure, humidity, as well as prevailing winds and air mass movements are all important in the creation of these potentially damaging hazards. An ice storm’s duration can last from a few hours to several days.  This project looks into the delicate formation, impacts, and general response to ice storms – specifically with the 1998 ice storm which took place from January 5th to January 10th in a large part of eastern Ontario, southwest Quebec, and the north eastern United States.

For six days in January of 1998, freezing rain covered an extensive area including Ontario, Quebec, New Brunswick, and parts of New York and England. According to Environment Canada, more than 80 hours of freezing rain totaling more than four inches in some areas more than doubled the annual average rain fall. The storm affected nearly 4 million people, leaving them without power for more than a day, and 700,000 people remained without power three weeks after the storm. Conservative estimates of damage costs exceed one-half billion dollars from this storm. The ice storm of 1998 directly affected more people in Canada than any other previous weather event in recorded history.

Ice storms are one of the most dangerous forms of weather in the world. They cause damage, injuries, and fatalities that extend hundreds of square miles. The term ice storm is used by the National Weather Service to describe a storm that produces a significant accumulation (1/4 inch or more) of ice during freezing rain. To produce this amount of ice, freezing rain usually has to occur for several hours. Ice storms lasting 12 hours or more generally produce ice accumulations several centimeters thick and affect an area that may range from a few square kilometers to areas covering several states. The typical ice storm swath is 30 mi wide and 300 mi long.

Ice storms are considered a rare commodity in the United States. On average ice storms generally warrant headlines once every three years. Research at the University of Oklahoma shows that freezing rain occurs most often throughout the Appalachian Mountains in central North Carolina, West Virginia, Pennsylvania, and New York. The Columbia River Valley in southern Washington and northern Oregon is also prone to stints of freezing rain. Ice storms generally occur during the months of December and January, and often take place near sunrise, usually the coldest time of the day.

Ice storms may be comprised of either glaze ice or rime ice. Meteorologists classify transparent and homogeneous ice forming on vertical and horizontal surfaces as glaze. Glaze ice resembles ice-cube ice in appearance. Its dense structure helps it cling to any surface on which it forms. In contrast, if the ice is milky and crystalline it is termed rime. Rime ice is less dense than glaze ice and clings less steadfastly. Therefore damage due to rime is generally minor compared to glaze ice.