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derecho

derecho dərā´chō [key], a long-lived windstorm over a wide expanse that is associated with a line of rapidly moving thunderstorms or showers. The winds in a derecho generally exceed 57 mph (92 kph) and may reach 100 mph (161 kph) or more derecho winds are produced by clusters of downbursts, with stronger winds being produced by microbursts within downbursts. The line of storms associated with a derecho typically takes on a broadly curved or bowed shape, known as a bow echo from its appearance on radar. A serial derecho, usually associated with a strong, moving low pressure system, contains multiple bow echoes within a squall line that usually is hundreds of miles long and traverses an extensive area. A progressive derecho is typically associated with a weak surface low pressure area and with a line of thunderstorms less than 250 mi (400 km) long the squall line usually remains relatively narrow as it progresses and may contain only a single bow echo. Hybrid derechos have characteristics of both serial and progressive derechos. Derechos typically cause so-called straight-line wind damage, in which the destruction is aligned in one general direction. Derecho winds can topple trees and power lines, overturn high-profile trucks and other vehicles, and even overturn mobile homes the sudden, widespread destruction they cause can lead to prolonged power outages.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

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