Madden–Julian Oscillation and Summer Precipitation/Drought in the Canadian Prairies

Warm-season precipitation over the Canadian Prairies plays a crucial role in several activities in environment and society and has particular importance to agricultural production over the region. This research investigates warm season precipitation deficits over the Canadian Prairies as they relate to tropical Pacific forcing by using the early summer 2015 drought as a case study. Results reveal that the significant deficit of precipitation and drought in May and June of 2015 were coincident a negative phase of Madden-Julian Oscillation (MJO)-4 index with a developing El Nino. Further investigation during the instrumental record (1979-2015) shows that the warm-season meteological drought in the Canadian Prairies and the corresponding atmospheric circulation anomalies over western Canada teleconnected with the lower boundary conditions in the tropical western Pacific when MJO is strong. MJO may play a crucial role in determining the summer precipitation anomaly in the western Canadian Prairie. When the tropical convection around MJO-4 index regions (centered over 140 E) is more active than normal, corresponding to negative MJO-4 indices, a Rossby wave train originated from western Pacific. The geopotential height anomaly associated with this phase of MJO-4 favors a negative precipitation anomaly in the Canadian Prairies.