13.2 North American Cyclones: Relationship to ENSO and NAO

Friday, 12 May 2000: 10:50 AM
James R. Angel, ISWS, Champaign, IL; and S. A. Isard

Past research by the authors has shown a strong link between North American cyclone activity and ENSO events. During El Nino years, cyclones tend to track further south into the southern U.S. At the same time, the “Alberta” cyclone track becomes less active. As a result, the Great Lakes region experiences fewer cyclones. During La Nina events, the “Alberta” cyclone track tends to become more active while the “East Coast” track becomes considerably less active. Research by others suggests that the influences of ENSO events on cyclones over North America can be further understood by considering as well the circulation features in the Atlantic. For example, the impacts of La Nina on temperature, precipitation, and snowfall in North America appear to differ depending on the phase of the North Atlantic Oscillation (NAO). This relationship will be examined for cyclones with historical data sets of cyclone tracks, appropriate ENSO indices, and the NAO index.
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