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Atlantic seaboard of the United States, a situation duplicated only once in the last 50 years. Nor'easters are rated by the Dolan-Davis Intensity Scale. The scale is not included in this document because it is based upon beach and dune erosion and overwash, none of which are relevant to Orange County,the Town of Carrboro or the Town of Hillsborough. Thunderstorms Severe thunderstorms can occur alone or in clusters,but affect relatively small areas compared to those affected by hurricanes or nor'easters. In eastern North Carolina, thunderstorms most frequently occur in the late afternoon or during the evening or night hours during the summer months. Summer thunderstorms involve lightning, strong winds, heavy rains and hail that can result in wildfires, localized wind damage and flash flooding. According to the North Carolina State Climate Office,thunderstorms typically are 15 miles or less in diameter and last an average of 20 to 30 minutes. Downbursts and straight-line winds associated with thunderstorms can produce winds of 100-150 miles per hour- enough to flip large trucks and endanger airplane landings and takeoffs. The National Weather Service considers a thunderstorm severe if it produces hail at least three-quarters of an inch in diameter,has winds of 58 miles per hour or greater or produces a tornado. Of the estimated 100,000 thunderstorms in the United States each year, only about 10% are classified as severe. Lightning, a major threat during a thunderstorm, is responsible for more deaths each year in the United States than are tornad e in 1' o s. S ce i htnin s ' g g tnkes are very unpredictable, the risk to individuals and property can be significant. Historic Impact of Thunderstorms in Orange County(including Carrboro &Hillsborough) I As the Hazard History table at the end of this section shows, a number of thunderstorm/high wind storm events and thunderstorm related events (hail and lightning)have been reported in Orange County. Severe Winter Storm Severe winter weather is typically associated with much colder climates;however, winter storms involving extremely cold temperatures, ice storms, and/or heavy snow have occurred in Orange County. The impact of a winter storm in Orange County can be significant. Although equipment such as snow plows is available in the region, winter storms can produce an accumulation of snow and ice on trees and utility lines resulting in loss of electricity and blocked transportation routes. Frequently, loss of electric power means loss of heat for residential customers, which poses an immediate threat to human life. As the Hazard History table at the end of this section indicates, ice storms, heavy snow, and extreme cold has impacted Orange County, including Carrboro and Hillsborough, several times from 1956 to 2008. 16