Atmospheric fronts over Poland (2006-2015)

The paper presents the spatial and temporal variations in the occurrence of fronts and days with no fronts over Poland in 2006-2015. The research was based on a database of the atmospheric fronts that moved over five selected stations located in the outermost regions of Poland and in the centre of the country. The database was created as a result of an analysis of synoptic charts from the website of the German weather service (Deutscher Wetterdienst; DWD). As is shown by the results, atmospheric fronts moved over Poland on approximately 65% of days of the year. However, their frequency in the individual regions was almost half of this, ranging from 33-39%. The annual variations in the number of fronts depended largely on the location of a given area and the atmospheric circulation prevailing there. In most years the maximum frequency of occurrence of atmospheric fronts was observed in November-January, and the lowest frequency was seen in February and September. The research confirms that there is a clear predominance of cold fronts, with warm and occluded fronts forming at around half the frequency of cold fronts. One characteristic feature is a decrease in the number of occluded fronts and days with different types of fronts moving from the north of Poland southwards. In the period under study, more than 80% of the sequences of days with atmospheric fronts included up to 6 days, even though there were also cases when fronts passed over Poland on 20 consecutive days.