Polar lows (PLs) are relatively small (a few to a few hundred kilometres in their radii) cyclones over oceans in high latitudes. They are associated with extreme winds and snowfall which present challenges to maritime and coastal activities. PLs are not reproduced well in reanalyses data nor by climate models that are used for seasonal predictions and long-term climate change projections. Therefore the work done in Blue-Action WP1 Improving long range forecast skill of risks for hazardous weather and climate events and this Case Study (CS3) has focused to marine cold-air outbreaks (MCAOs) in which cold Arctic air overlays warmer sub-Arctic open waters, creating a condition of large-scale atmospheric instability. Data supporting this deliverable have been uploaded to Zenodo too: https://zenodo.org/record/4274277

The Blue-Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852.