Atmospheric circulation comparisons between the 2001 and 2002 and the 1961 and 1988 Canadian Prairie droughts

The 2001 and 2002 Canadian Prairie droughts were unusual climatological events in terms of their extreme precipitation anomalies and extraordinary persistence. Over the west-central Prairie Provinces, well below normal precipitation was recorded for a remarkable eight consecutive seasons from autumn 2000 to summer 2002. Analysis of the mid-tropospheric circulation during these droughts indicates that the patterns were markedly different from those associated with the severe, multi-season Prairie droughts of 1961 and 1988. In particular, the circulation during 2001 and 2002 lacked the distinct meridional flow over the North Pacific and North America that has been associated with previous dry periods over western Canada. Moreover, the evolution and persistence of the 2001-2002 droughts have no clear relationships with large-scale teleconnection patterns that have influenced past climate extremes over western regions of the country. Results suggest that the recent droughts may be related to a northward extension of persistent drought producing circulation anomalies that influenced the continental United States. These differences in circulation indicate that further research is required to gain a better understanding and aid in the prediction of extended dry periods over North America.