Tornado circa 1955 US Weather Bureau; Cyclone Prediction & Tracking

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• published: 05 Dec 2012
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more at http://scitech.quickfound.net/weather_news_and_links.html Explains the work done by the Weather Bureau (now the National Weather Service) in predicting and tracking tornadoes. "Made possible as a public service by University of California Extension Media Center, United Gas Corporation, and Texas Eastern Transmission Corporation. Cooperation of WKY-TV, Oklahoma City, Oklahoma and Southwestern Bell Telephone Company." Public domain film from the Library of Congress Prelinger Archive, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original). http://en.wikipedia.org/wiki/Tornado A tornado is a violently rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters or cyclones, although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation. Tornadoes come in many shapes and sizes, but they are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds less than 110 miles per hour (177 km/h), are about 250 feet (76 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (483 km/h), stretch more than two miles (3.2 km) across, and stay on the ground for dozens of miles (more than 100 km). Various types of tornadoes include the landspout, multiple vortex tornado, and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud. They are generally classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air frequently develop in tropical areas close to the equator, and are less common at high latitudes. Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirls, and steam devil. Tornadoes have been observed on every continent except Antarctica. However, the vast majority of tornadoes in the world occur in the so-called "Tornado Alley" region of the United States... There are several scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and assign a rating... http://en.wikipedia.org/wiki/Storm_Prediction_Center The Storm Prediction Center (SPC), located in Norman, Oklahoma, is tasked with forecasting the risk of severe thunderstorms and tornadoes in the contiguous United States. The agency issues convective outlooks, mesoscale discussions, and watches as a part of this process. Convective outlooks are issued for Day 1, Day 2, Day 3, and Day 4--8, and detail the risk of severe thunderstorms and tornadoes during the given forecast period, although tornado, hail, and wind details are only available for Day 1. Days 2 and 3, as well as 4--8 used a probabilistic scale, determining the probability for a severe weather event in percent... Watches are issued when forecasters are confident that severe weather will occur, and usually precede the onset of severe weather by one hour... The Storm Prediction Center is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce (DoC). The Storm Prediction Center was previously known as the National Severe Storms Forecast Center and was located in Kansas City, Missouri. In October 1995, the National Severe Storms Forecast Center relocated to Norman and was renamed the Storm Prediction Center... The Storm Prediction Center began in 1952 in Washington, D.C. as SELS (Severe Local Storms Unit), a special unit of forecasters in the Weather Bureau. In 1954, the unit moved to Kansas City. SELS began issuing convective outlooks in 1955, and began issuing radar summaries every three hours in 1960..