A colder and wetter winter in the Canadian Rockies this year has led to near-record snowfall, potentially benefiting the Northwest Territories in terms of drought and wildfire risks this summer. However, the outcome largely hinges on the speed of snowmelt.
The northern regions of the Rockies, which serve as a vital water source for the Northwest Territories, have witnessed higher-than-average snowfall this season. Despite this, the Canadian Drought Monitor revealed that parts of the Northwest Territories were facing “abnormally dry” to “severe drought” conditions by the end of March, with precipitation levels falling below 60 percent of normal in significant areas of the territory.
In recent years, wildfires in the Northwest Territories have been exacerbated by insufficient snow and rainfall, resulting in low soil moisture levels and dried-out vegetation acting as combustible materials during the summer and fall seasons. Kate Hale, an assistant professor at the University of British Columbia, expressed cautious optimism regarding drought and wildfire conditions in the Northwest Territories this year, citing the substantial snowpack in the higher-altitude watershed areas.
Snowpack estimates from early March indicated levels ranging from 110 to 150 percent above normal in the headwater regions of the Mackenzie River Basin. In contrast, snowpack levels in Yellowknife and around Great Slave Lake were recorded at 70 to 90 percent of the average.
Hale emphasized that the future scenario of flooding, drought, and wildfires in the N.W.T. hinges on the pace of snowmelt in the upcoming weeks and months. She noted that if the snow melts at a moderate rate, the territory could witness relief in terms of wildfire risks. Conversely, a rapid snowmelt due to hot conditions in May could lead to flooding and a challenging wildfire season.
Regarding drought, she mentioned that a single season of significantly above-average snowpack might not completely mitigate long-term aridity in the region but could make a difference. The snow-covered mountains act as a natural reservoir, gradually releasing water downstream during the summer months.
Hale described the watershed as a series of “buckets,” each serving different purposes such as streamflow, soil replenishment, and evaporation into the atmosphere. She highlighted that soil conditions play a crucial role in wildfire-affected areas, as some burnt soils become hydrophobic, resisting water absorption and potentially increasing the risk of flooding.
John Pomeroy, a professor at the University of Saskatchewan’s hydrology center, mentioned that it typically takes more than one wet year to replenish groundwater levels. Referring to Great Slave Lake’s historically low water levels in recent years, he suggested that this year’s snowpack might offer only a slight reprieve.
Hale pointed out that this year’s above-average snowpack in the Rockies falls within the expected range of year-to-year fluctuations influenced by climate change. She explained that as temperatures rise and weather patterns become more erratic, there could be alternating periods of average to historical precipitation and temperatures followed by below-average snow seasons.
The weather phenomenon La Niña, known for bringing increased precipitation and cooler temperatures to western Canada, might have contributed to the heightened snowpack this year. Pomeroy underlined the clear climate change signals evident in temperature and precipitation patterns, emphasizing the increasing intensity and duration of droughts and wet periods, leading to fluctuating challenges like fires, crop failures, and floods.