Kartläggning av snökanoner över Östersjön
Convective snowbands is a weather phenomenon that is associated with heavy snowfall in a limited area. They are formed over ice-free parts of e.g. the Baltic Sea when there is a cold easterly airflow over relatively warm water. These convective snowbands can cause large amounts of snow along the Swedish east coast, often causing traffic hazards. Sometimes they can even paralyze an entire community. In this study, convective snowbands that have formed over the Baltic Sea during the period 1980-2009 are examined, in order to find out how often they occur, what place they are most common and in what month they usually appear. Parameters such as sea-and air temperature, wind direction, directional shear, ice cover and snow amounts are used to define days with convective snowbands.The study shows that convective snowbands occurred during 73 days during the years 1980 to 2009, ie, an average of 2.4 days per year. Gävle and Söderala were the places where convective snowbands were most common, with 25 and 16 days. Both places are in the northern part of the study area. Convective snowbands existed from October to March, but was overall most common in December (34%), followed by January (26%). In the northern and central regions, the monthly distribution were relatively equal. The southern area distinguished itself by being more limited in December and January.