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

Teleconnections among El Niño and La Niña 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 Niño 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 Niño events is significantly higher than for non-El Niño periods. This relationship occurs during the second summer following the mature stage of El Niño events. Further analysis reveals that La Niña 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 Niña periods. Even though the relationships among El Niño, La Niña, 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.