T he Arctic oceans give birth to intense mesoscale low-pressure systems, usually generated by outbreaks of cold, dry polar air over warm water. These systems are called polar lows. The classical polar low is included as a subtype that is restricted to maritime systems with near-surface winds exceeding 15 m s–1. These types of polar lows can exhibit deep convection, a warm core, and lifetimes of a few hours to a few days. Sensible heat fluxes from the oceans play an important role in creating these systems, while latent heat fluxes can become important in their mature and decaying stage. They may appear visually similar to tropical cyclones on satellite imagery with an eyelike feature. Numerical simulations of polar lows are often unsuccessful. This can be due to poor initial and boundary conditions, model resolution, and the choice of cloud microphysical scheme. Due to their rapid genesis, small size, and occurrence over data-sparse oceans, polar lows pose a serious threat to mariners and coastal interests. Polar-orbiting satellite imagery could be culled to develop a useful database of polar lows, improving what we know about them and how they can be simulated. Unlike tropical cyclones, polar lows are not routinely identified and tracked in real time. Their occurrence in high latitudes at the limits of usable geostationary satellite imagery makes tracking difficult. To obtain cases for scientific studies, including the improvement of polar low representation in numerical weather prediction models, these systems must be manually identified and matched with coincident data. The Norwegian Sea Surface Temperature and Altimeter Synergy (STARS) project (http://polarlow