The impact of extreme storms on coastal oceanographic conditions on the west coast of British Columbia: A case study of the 18-21 November 2024 Bomb Cyclone.

Human-induced climate change is expected to increase the intensity and frequency of major storms. Explosive cyclogenesis (“bomb cyclone”) is among the most violent of atmospheric events and occurs when there is a rapid deepening of the pressure at the centre of a cyclonic system over a period of 24h. Bomb cyclones generally form over the ocean in winter and are relatively common on the Atlantic coast of North America, where they can be manifested in nor’easters in the form of blizzards up north and hurricanes down south – Hurricane Milton experienced explosive cyclogenesis.

In this study, we examine the bomb cyclone that impacted the British Columbia (BC) coast of Canada during 18-21 November, 2024. This extreme weather event was accompanied by hurricane strength wind gusts of up to 170 km/h and extreme storm waves. Atmospheric pressure in the cyclone centre fell as low as 940 hPa and the storm caused large-scale power outages and strongly affected coastal infrastructure. The cyclone and associated storm produced a strong storm surge, significant seiches, infragravity waves and modified the oceanic circulation, impacting inlet and coastal ecological habitats. We examine real-time observations recorded by tide gauges along with simultaneous atmospheric microbarographs from the Canadian Hydrographic Service to provide estimates of the statistical and extreme parameters of the sea level and atmospheric pressure oscillations. Additional observations of water properties, oceanic circulation, acoustic backscatter and undersea video from the Ocean Networks Canada coastal sub-sea networks provide a comprehensive view of the impact on inlet and coastal habitat by this extreme weather event.