The usual clashes between warm air fronts from the Atlantic and cold fronts from Siberia have so far failed to happen this season, leading to an unseasonably warm winter, says Professor Sirje Keevalik of the Tallinn University of Technology's Marine Systems Institute.
“A battle between low pressure fronts from the Atlantic and the expanding Siberian cold high pressure area, where neither side wants to capitulate, usually takes place over the country [Estonia], but this time it happened differently,” Keevalik said in a press release today.
She said that the paths of cyclones are determined by the polar front, which divides cold, Arctic air from warm, temperate air, creating four or five north-south ridges around the [north] pole.
This year, strong winds are moving from west to east on the upper reaches of the polar front and the ridges are slowly moving in the same direction.
“The polar front has practically come to a halt in a position where Europe is south of the front and North America, north, this early winter. That has caused rain and above zero temperatures here and snow and frost in America,” Keevalik said.
She said that is hard to predict how long the warm spell will last, adding that even if the Siberian cold air masses arrive here, they won't last long, as the sun is ever higher and spring is on its way.