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Anoka County Multi-Jurisdictional All Hazards Mitigation Plan 81 ground. A bolt of lightning reaches a temperature approaching 50,000 degrees in a split second. In the United States, 75 to 100 citizens are killed each year by lightning. Lightning's electrical charge and intense heat electrocutes on contact, splits trees and ignites fires. Hail is produced by many strong thunderstorms and is a product of the updrafts and downdraf ts that develop inside the clouds of a thunderstorm where super cooled water droplets exist. The transformation of droplets to ice requires a temperature below 32 degrees, and a catalyst in the form of tiny particles of solid matter, or freezing nuclei. Hail can be smaller than a pea or as large as softballs and can be destructive to property, crops, livestock, and people. 4.2.1.9 Severe Weather - Tornados Tornados are violent windstorms characterized by a twisting, funnel-shaped cloud. A tornado is spawned by a thunderstorm or hurricane and produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly. A funnel does not need to reach to the ground for a tornado to be present. A debris cloud beneath a thunderstorm is all that is needed to confirm the presence of a tornado. The damage from a tornado is a result of the high wind velocity and wind-blown debris. Tornados can occur at any time of the year; however, the season is generally March through August. Over 80% of all tornadoes strike between noon and midnight. The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more. Damage paths can be in excess of 1 mile wide and 50 miles long. Even with advances in meteorology, adequate warning time for tornadoes is short or sometimes not possible. The intensity, path length, and width of tornadoes are rated according to a scale developed by T. Theodore Fujita and Allen D. Pearson. The Fujita-Pearson Tornado Scale is presented below. Tornadoes classified as EF0-EF1 are considered weak, those classified as EF2-EF3 are considered strong, while those classified as EF4-EF5 are considered violent. Enhanced Fujita Tornado Scale Description Table EF- Scale Damage Winds (mph) Description EF-0 Light 65-85 Chimney damage, tree branches broken EF-1 Moderate 86-110 Mobile homes overturned EF-2 Considerable 111-135 Considerable damage, trees downed, mobile homes demolished EF-3 Severe 136-165 Roofs/walls torn down, trains and cars overturned EF-4 Devastating 166-200 Well-constructed walls leveled EF-5 Incredible 200 + Homes lifted off foundation and carried considerable distances