Teleconnections between El Niño and La Niña events and summer extended dry spells on the Canadian Prairies

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Teleconnections among El Nino and La Nina events, North Pacific sea surface temperature anomalies, and summer (June, July, August) extended dry spells on the Canadian Prairies are documented and analysed. For the period 1948-1991, results show the majority of El Nino events associated with a persistent North Pacific SST anomaly pattern consisting of anomalously cold water in the east-central North Pacific and anomalously warm water along the west coast of North America. The average number of summer extended dry spells on the Prairies associated with El Nino events is significantly higher than for non-El Nino periods. This relationship occurs during the second summer following the mature stage of El Nino events. Further analysis reveals that La Nina events are associated with opposite North Pacific SST anomaly patterns that also tend to persist for several seasons. The average number of summer extended dry spells associated with these events is significantly lower than for non-La Nina periods. Even though the relationships among El Nino, La Nina, North Pacific SST anomalies, and extended dry spells show high variability, the results of this study may be considered as an initial step towards contributing to a long-range forecasting technique of summer extended dry spells on the Canadian Prairies. Copyright © 1999 Royal Meteorolog- ical Society.