Analysis of consecutive droughts on the Canadian Prairies

Canadian Prairie precipitation totals were classified using fixed thresholds corresponding to the 10th percentile and median for the growing season (April to August) and agricultural year (September to August), in order to study the incidence of consecutive drought. These time frames are significant to water supply and agricultural activities. Consecutive drought events were classified as either back to back years with precipitation below the 10th percentile, or a year with precipitation below the 10th percentile followed by one or more years with less than median precipitation. The Palliser Triangle (an area in the southern Prairies) most consistently recorded consecutive drought events. While generally receiving higher precipitation totals, stations in the north were not immune to such events. Using the Palmer Drought Index, severe droughts were detected in the 1910s, 1930s and 1960s, corresponding to notably dry periods across the Canadian Prairies as a whole.