Orange County NC Website
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has significant restrictions on new development in floodplain areas. The Town of <br /> Hillsborough allows construction within floodplains provided the finished building <br /> elevation is high enough to sufFiciently prevent flooding. <br /> Flooding is normally associated with other types of events such as hurricanes and <br /> thunderstorms. Past occurrences of flooding in Orange County is documented in the <br /> appropriate hazard section with which the flooding occurred. <br /> Tornados <br /> Many times severe storms, such as thunderstorms and hurricanes,can produce smaller, <br /> more localized storms. Tornados, typically the by-product of a larger storm, are violently <br /> rotating columns of air that come in contact with the ground. Tornados have a more <br /> localized impact than a hurricane or nor'easter. Tornados generally produce a narrow path <br /> of concentrated destruction from 0.01 mile wide to greater than 1 mile wide. Tornados may <br /> also produce paths of destruction from less than 1 mile in length to greater than 100 miles <br /> in length. <br /> The destruction caused by tornados may range from light to severe depending on the path <br /> of travel. Typically, structures of light construction, such as residential homes, suffer the <br /> greatest damage from tornados. Tornados are generally rated according to the Fujita- <br /> Pearson Sca1e as shown in the table below. <br /> The Fujita-Pearson Tornado Scale <br /> F-Scate Damage Winds(mph) Path Length Mean Width <br /> (mites) (miles) ' <br /> FO Li ht 40-72 <1.0 <0.01 , <br /> F 1 Moderate 73-112 1.0-3.1 0.01-0.03 <br /> F2 Considerable 113-157 3.2-9.9 0.04-0.09 <br /> F3 Severe 158-206 10-31 0.1-0.3 <br /> F4 Devastatin 207-260 32-99 0.32-0.99 <br /> FS Incredible 261-318 100+ 1.0+ <br /> Source:North Carolina Division of Emergency Management, 1998:Local Hazard Mitigation Planning Manual. <br /> Because tornados are typically a by-product of thunderstorms,they have a higher likelihood <br /> of occurrence. In North Carolina, tornados and thunderstorms are most likely to occur <br /> during the spring months (March through June). Tornados during these months have also <br /> been strongest,resulting in the greatest amount of harm or damage. Tornados can occur at <br /> any time of day but are mostly likely to form between the hours of 3 p.m. and 9 p.m. <br /> Historic Impact of Tornados in Orange County <br /> North Carolina ranks 20th out of the 50 states for frequency of tornados, 19th for number of <br /> tomado related deaths, 17th for injuries and 20th for cost of damages (source: Top 20 <br /> 10 <br />