Polar lows are associated with severe weather conditions, such as strong, sometimes hurricane-force, winds and heavy snow showers. The weather changes associated with polar lows are abrupt.
Consequently, polar lows pose a threat to coastal communities, maritime and air transport, and oil and gas platforms. Some polar lows have caused the loss of human lives. For instance, in October 2001, the Torsvåg polar low developed near a fishing village on Vannøya island, in northern Norway. A boat capsized in the strong winds, killing a crew member.
Closer than we think
Polar lows develop in the northern and southern hemispheres, between the poles and a latitude of around 40 degrees north and 50 degrees south, respectively. They form near the sea-ice edge (where the sea ice meets the open ocean) or snow-covered continents, when very cold air flows out over the relatively warm ocean.
The heat and humidity of the ocean provides energy to the cold air to feed the development of polar lows. Polar lows dissipate when they make landfall or move over the sea ice and the energy source disappears.
Near Canada, we observe polar lows over the Labrador Sea, Davis Strait and Hudson Bay. These regions have low population density, so the risk of a polar low affecting a community is small.
In other parts of the world polar lows can be dangerous. Norway and Japan suffer from the impacts of these storms since they have important population centres located in the coastal regions where polar lows can develop. The weather associated with polar lows can lead to road and airport closures, and there is also a risk of snows avalanches. For instance, in January 2019, a particularly intense polar low made landfall in Norway, causing road closures and the isolation of a village.
With climate change, we can expect the location and the frequency of polar lows to shift. In the North Atlantic, for example, polar lows may form further north, as the sea ice edge retreats, and with decreased frequency. However, many questions remain unanswered regarding the impact of climate change on the frequency and spatial distribution of polar lows.
Storms that are hard to predict
Accurate forecasts of polar lows are essential to avoid any damage from them. But forecasting polar lows is challenging due to their small size and short lifetime.
As with other weather forecasts, the essential ingredients for a correct polar low forecast are an atmospheric model that performs well and good knowledge of the current state of the atmosphere. Yet a lack of conventional observations (such as observations from surface stations) over the ocean and near the poles means that the initial conditions are still not good enough.