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caused by precipitation over a longer time period and over a given river basin. A combination of river basin physiography, local thunderstorm movements, past soil moisture conclitions, and the degree of vegetative clearing determine the severily ora flooding event. Flooding is typically most severe in areas of the floodplain immediately adjacent to major streams and rivers. 2. Flooding can be as frequent as the occurrence of a spring rain or summer thunderstorm. The amount of precipitation produced by storm events determines the type of flooding. Flash floods, which typically occur more frequently than general floods, occur along small streams and creeks of the type that are present throughout Cabarrus County. The undermining or waShing out of roads is typically associated with flash floods. General flooding occurs less frequently and as the result of much larger storm events such as hurricanes. These larger storm events occur along the East Coast of the United States most often in the late summer and fall. 3. The total economic and loss of life impact depends greatly on the amount of development within the area. Currently, Cabarrus County has a moderate amount of development, mostly residential, along the floodplains of major streams and Rocky River. Both flash flooding and longer-term general flooding can cause massive damage and destruction to the structures located in these floodplains. D. Tornadoes (Map A-1 Cabarrus County Multi-Hazards) 1. Many times severe storms, such as thunderstorms and hurricanes, can produce smaller, more localized storms. Tornadoes, typically the by-product of a larger storm, are violently rotating columns of air that come in contact with the ground. Tornadoes have a more localized impact than a hurricane. Tornadoes generally produce a narrow path of concentrated destruction from 0.01 mile wide to greater than 1 mile wide. Tornadoes may also produce paths of destruction from less than 1 mile in length to greater than 100 miles in length. The destruction caused by tornadoes may range from light to severe depending on the path of travel. Typically, structures of light construction, such as residential homes, suffer the greatest damage from tornadoes. 2. Because tornadoes ar~e typically a by-product of thunderstorms, they have a higher likelihood of occurrence. Tornadoes and thunderstorms are most likely to occur during the spring months, March through June. Tornadoes during these months have also been strongest, resulting in the greatest.amount of harm or damage. E. Thunderstorms. Severe thunderstorms most frequently occur in the summer in Cabarms County. These usually occur in the late afternoon or dining the evening or night hours. Summer thunderstorms involve lightning, strong winds and heavy rains that can result localized wind damage, flash flooding and wildfires. The overall impact of thunderstorms could be expected to be low due to the localized nature of the storms, but damage could be severe in those areas directly affected. F. High Wind Mitigation Activities 1. There are a number of natural hazards that have the potential to include high wind damage - hurricanes, tornadoes, severe winter storms, and thunderstorms. In 1997, the Federal Draft Annex A v.3.1 A-2 1 July 2002