Climate Fact: ENSO and Winter Tornadoes
The El Niño-Southern Oscillation (ENSO), or the cyclical movement of heat in the tropical Pacific Ocean, affects atmospheric phenomena throughout the world. Its effects are the most pronounced during the winter, when the temperature difference between the atmosphere and the oceans is the greatest.
The cycle affects the strength and position of the Pacific Jet Stream, an upper atmosphere wind current that flows from the Pacific over North America. During La Niña phases of the cycle, the Jet Stream is weaker than average and flows in an arcing pattern over the northern U.S. During El Niño phases, the Jet Stream strengthens and flows over the southern United States. The position and strength of this air current affect the location and frequency of wintertime (January through March) tornado occurrences. Winter tornado outbreaks are concentrated in the southeastern U.S. For the United States as a whole, winter tornadoes are most frequent during neutral ENSO phases, second most frequent during La Niña phases, and the least frequent during El Niño phases.
(Source: Cook, AR and Schaefer, JT et al. “The Relation of the El Niño-Southern Oscillation (ENSO) to Winter Tornado Outbreaks.” Monthly Weather Review 136 (2008): 3121-3137.)
Earth Gauge is funded by the Kendeda Foundation, the Park Foundation, NOAA Office of Education, and the U.S. Environmental Protection Agency's Office of Wetlands, Oceans, and Watersheds.The Earth Gauge newsletter was developed under Cooperative Agreement No. X783185101-0 awarded by the U.S. Environmental Protection Agency. EPA made comments and suggestions on the document intended to improve the scientific analysis and technical accuracy of the document. However, the views expressed in this document are those of the National Environmental Education Foundation, and EPA does not endorse any products or commercial services mentioned in this publication. Any use of information from Earth Gauge in television, radio or other forms of media are subject to these same limitations.
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Climate Fact: ENSO and Winter Tornadoes
The El Niño-Southern Oscillation (ENSO), or the cyclical movement of heat in the tropical Pacific Ocean, affects atmospheric phenomena throughout the world. Its effects are the most pronounced during the winter, when the temperature difference between the atmosphere and the oceans is the greatest.
The cycle affects the strength and position of the Pacific Jet Stream, an upper atmosphere wind current that flows from the Pacific over North America. During La Niña phases of the cycle, the Jet Stream is weaker than average and flows in an arcing pattern over the northern U.S. During El Niño phases, the Jet Stream strengthens and flows over the southern United States. The position and strength of this air current affect the location and frequency of wintertime (January through March) tornado occurrences. Winter tornado outbreaks are concentrated in the southeastern U.S. For the United States as a whole, winter tornadoes are most frequent during neutral ENSO phases, second most frequent during La Niña phases, and the least frequent during El Niño phases.
(Source: Cook, AR and Schaefer, JT et al. “The Relation of the El Niño-Southern Oscillation (ENSO) to Winter Tornado Outbreaks.” Monthly Weather Review 136 (2008): 3121-3137.)
Earth Gauge is funded by the Kendeda Foundation, the Park Foundation, NOAA Office of Education, and the U.S. Environmental Protection Agency's Office of Wetlands, Oceans, and Watersheds.The Earth Gauge newsletter was developed under Cooperative Agreement No. X783185101-0 awarded by the U.S. Environmental Protection Agency. EPA made comments and suggestions on the document intended to improve the scientific analysis and technical accuracy of the document. However, the views expressed in this document are those of the National Environmental Education Foundation, and EPA does not endorse any products or commercial services mentioned in this publication. Any use of information from Earth Gauge in television, radio or other forms of media are subject to these same limitations.
Earth Gauge is a Program of the
National Environmental Education Foundation
4301 Connecticut Avenue, Suite 160
Washington, DC20008
V (202) 261-6490
F (202) 261-6464
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