https://doi.org/10.1016/j.wace.2026.100926

Bruno S. Sobral, Tamar S. Richards-Thomas, Stephen J. Déry, ()2026 Meteorological features and hydrological impacts of three exceptional atmospheric rivers in British Columbia's Nechako River Basin, Weather and Climate Extremes, Volume 53, 2026, 100926, https://doi.org/10.1016/j.wace.2026.100926 .

Atmospheric Rivers (ARs) significantly influence global precipitation patterns in the mid-latitudes, profoundly impacting British Columbia's Nechako River Basin (NRB), a critical region for water resources management in western Canada. This study examines three exceptional AR events in 1952, 1978, and 2009, and uses the SIO-R1-AR Catalogue, ERA5/ERA5-Land reanalyses, and observed discharge/water level data to analyse the spatio-temporal variability of atmospheric conditions and hydrological responses in the NRB. A latitudinal transect revealed a west-to-east reduction in integrated water vapour transport (IVT), shaping precipitation patterns and the magnitude of terrestrial impacts. Moisture convergence peaks during AR events align with low mean sea-level pressure, driving elevated precipitation west of the watershed. The Upper Nechako sub-basin, where the Nechako Reservoir lies, experienced precipitation volumes of over 1 km3 (equivalent to ≥72 mm) during each event. Percentile analysis highlights varied hydrological impacts, with 1952 showing moderate (<40th) percentiles in river discharge east of the NRB due to freezing conditions. Conversely, 1978 and 2009 exceeded the 90th percentiles in the western and northwestern parts of the NRB, reflecting rapid discharge during the warmer autumn season. Our findings reveal that AR-driven hydrological extremes in the NRB result from a synchronization of orographic moisture penetration and thermodynamic efficiency; while colder events accumulate snowpack, AR pulses during autumn accelerate runoff into the reservoir system. These exceptional ARs replenish vital water resources for energy production, agriculture and ecological processes, yet increase flood risks by accelerating snowmelt and runoff. Enhanced AR forecasting is crucial for optimizing flood management and water storage while strengthening regional resilience against these impactful river-shaped storms in the NRB

https://doi.org/10.1016/j.wace.2026.100926