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Unformatted text preview: Tstorms & Tornadoes Ch 10 Thunderstorms A storm containing lightening and thunder; convective storms Severe thunderstorms: one of large hail, wind gusts greater than or equal to 50 knotts, or tornado Ordinary Cell Thunderstorms y Air-mass thunderstorms: limited wind sheer y Stages: cumulus, mature, dissipating y Entrainment, downdraft, gust front Multi-cell Thunderstorms y Thunderstorms that contain a number of convection cells, each in a different stage of development, moderate to strong wind shear; tilt, over shooting top y Gust Front: leading edge of the cold air out-flowing air; shelf cloud, roll cloud, outflow boundary y Micro-bursts: localized downdraft that hits the ground and spreads horizontally in a radial burst of wind; wind shear, virga y Squall-line thunderstorms- line of multi-cell thunderstorms, pre-frontal squall- line, derecho y Meso-scale Convective Complex (MCC): a number of individual multi-cell thunderstorms grow in size and organize into a large circular convective weather system; summer, 10,000km 2 Supercell thunderstorms y Large, long-lasting thunderstorm with a single rotating updraft y Strong vertical wind shear y Outflow never undercuts updraft y Classic, high precipitation and low precipitation supercells y Cap and convective instability y Rain free base, low-level jet Thunderstorms and the Dryline y Sharp, horizontal change in moisture y Thunderstorms form just east of dryline Floods and Flash Floods y Flash floods rise rapidly with little or no advance warning; many times caused by stalled or slow thunderstorm Topic: Big Thompson Canyon y July 31, 1976, 12 inches of rain in 4 hours created a flood associated with $35.5million in damage and 135 deaths y Read about it in the text Distribution of Thunderstorms y Most frequent Florida, Gulf Coast, Central Plains y Fewest Pacific coast and Interior valleys...
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This note was uploaded on 09/25/2011 for the course 670 201 taught by Professor Hopey during the Spring '11 term at Rutgers.
- Spring '11