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Anoka County <br />MINNESOTA <br />Respectful, Innovative, Fiscally Responsible <br />Enhanced Fuiita Tornado Scale Description Table <br />Anoka County 2019 <br />Multi -Jurisdictional <br />All Hazards Mitigation Plan <br />EF- <br />Scale <br />Damage <br />Winds <br />(mph) <br />Description <br />EF-0 <br />Light <br />65-85 <br />Chimney damage, tree branches broken <br />EF-1 <br />Moderate <br />86-110 <br />Mobile homes overturned <br />EF-2 <br />Considerable <br />111-135 <br />Considerable damage, trees downed, mobile homes demolished <br />EF-3 <br />Severe <br />136-165 <br />Roofs/walls torn down, trains and cars overturned <br />EF-4 <br />Devastating <br />166-200 <br />Well -constructed walls leveled <br />EF-5 <br />Incredible <br />200 + <br />Homes lifted off foundation and carried considerable distances <br />4.2.1.10 Severe Weather - Tropical Storm/Hurricane <br />A hurricane is a tropical storm with winds that have reached a constant speed of 74 miles per <br />hour or more. Hurricane winds blow in a large spiral around a relative calm center known as the <br />"eye." The "eye" is generally 20 to 30 miles wide, and the storm may extend outward 400 miles. <br />As a hurricane approaches, the skies will begin to darken and winds will grow in strength. As a <br />hurricane nears land, it can bring torrential rains, high winds, and storm surges. A single <br />hurricane can last for more than 2 weeks over open <br />waters and can run a path across the entire length of <br />the eastern seaboard. August and September are <br />peak months during the hurricane season that lasts <br />from June 1 through November 30. <br />The center, or eye, of a hurricane is relatively calm. <br />The most violent activity takes place in the area <br />immediately around the eye, called the eye wall. At <br />the top of the eye wall (about 50,000 feet), most of <br />the air is propelled outward, increasing the air's <br />upward motion. Some of the air, however, moves <br />inward and sinks into the eye, creating a cloud -free <br />area. <br />Tropical cyclones are classified as follows: <br />Tropical Depression An organized system of clouds and thunderstorms with a defined <br />circulation and maximum sustained winds of 38 mph (33 knots) or less. <br />Tropical Storm An organized system of strong thunderstorms with a defined circulation and <br />maximum sustained winds of 39 to 73 mph (34-63 knots). <br />Hurricane An intense tropical weather system with a well-defined circulation and maximum <br />sustained winds of 74 mph (64 knots) or higher. Hurricanes are called "typhoons" in the western <br />Pacific, while similar storms in the Indian Ocean are called "cyclones." <br />81 <br />