A Study of the Effect of El Niño on the Weather of U.S. Cities

Studies have shown that El Niño alters the tracks of extratropical cyclones to the south over North America during the winter months. This shift from the normal tracks of storms results in differences in weather conditions. In this study an analysis of data sets for fourteen different stations across the continental United States was conducted to determine the effects of El Niño on the normal weather conditions of U.S. cities. The analysis was performed for the winter months of December 1997 through March 1998 to determine deviations from normal due to the changes associated with the 1997-1998 El Niño. This analysis was accomplished by calculating the deviations from 30-year normals for both temperature and precipitation on a monthly basis. All of these stations' weather changed due to the El Niño event. Furthermore, the results show that most stations experienced an increase in precipitation and temperature. Also, the southern-most stations deviated further from normal than did the northern-most stations.