The hottest May on record, and snow packs across B.C. that are at extremely low levels, are two of the factors that have caused the BC River Forecast Centre to say that there is a high risk of province-wide drought this summer.
As of June 1, the provincial snowpack was substantially below normal, averaging 29 per cent of normal readings across B.C. By contrast, on June 1, 2022 the average of all snow stations in B.C. was 165 per cent of normal. The South Thompson basin is at 33 per cent of normal readings, while the North Thompson basin is at 16 per cent.
The June 1 report notes that flood risk from snowmelt is largely over for the season, as most rivers in B.C. have experienced their peak flows and are now rapidly declining.
Many mid- and high-elevation automated snow weather stations measured record low snow for June 1 or recorded the earliest snow-free date of the season. However, flood risk from extreme rainfall events remains a possibility, particularly in the B.C. Interior.
Several factors have generated a high risk of province-wide drought in summer 2023, including the lingering effects of the fall 2022 drought; unusually dry and warm conditions in winter 2022-23 and spring 2023; an exceptionally rapid and early 2023 snowmelt; and the high likelihood of above normal temperatures this summer.
May 2023 was the hottest May on record in B.C. Mean temperature anomalies ranged from +1.1 to +5.1 C above normal, and several stations with records dating back to the 1800s measured all-time record May heat, including Victoria Gonzales (where records date to 1875), Quesnel airport (1893), and Kelowna (1899). Another heat wave occurred during the the week of June 6.
Seasonal forecasts from Environment Canada indicate a very high likelihood of above normal temperatures this summer (June, July, and August). Potential impacts of prolonged hot and dry weather may include negative effects on fish and aquatic communities due to reduced habitat area and higher water temperatures); increased susceptibility to wildfire due to the decrease of the perennial snow pack and overall drier conditions; and severe concerns around the availability of water for human use and recreational activities.
The report notes that long-range precipitation is difficult to forecast accurately over long lead times, so there is uncertainty as to how the 2023 summer season will play out. There is a chance that wet weather could once again dominate the summer season, as it it did in 2019, which would at least partially ease the risk of low flows.
According to the provincial government’s drought information portal, both the North and South Thompson basins were, as of June 8, at drought level 2, which means that adverse impacts to socio-economic or ecosystem values are unlikely. There are six drought levels in B.C., with zero meaning there is sufficient water to meet needs and 6 meaning that adverse impacts to socio-economic or ecosystem values are almost certain.