Winter is loosening its grip on the Northern Hemisphere, and greens and browns are replacing white on the landscape. But the seasonal change in March 2020 in Northern Europe is less dramatic than most years.
This natural-color satellite image shows snow cover in Scandinavia and the Baltic region in early spring 2020. It is a composite of two images acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on March 20 and 21. The composite maximizes the cloud-free area visible from space.
While snow covered much of Norway and the northern parts of Sweden and Finland, the southern end of each country appeared snow-free—including the capital cities of Oslo, Stockholm, and Helsinki. (For a seasonal comparison, see this image from March 2018.) The cities were virtually snow-free for much of winter 2019-20. For example, Helsinki saw no new snowfall in January or February, according to news reports. Numerous ski resorts across Europe had to rely on imported and artificial snow.
Warm winter temperatures were one reason for the sparse snowfall. According to NOAA, the December 2019 to February 2020 period was the warmest on record in Europe, and the January-February period was the warmest on record for the Northern Hemisphere. “The strong polar vortex has kept much of the frigid air in the Arctic, leaving the mid-latitudes warmer and generally less snowy than normal,” said Jennifer Francis, a scientist at Woods Hole Research Center.
The map above shows land surface temperature anomalies for January to March 2020 in northern Europe. Orange and red colors indicate areas that were warmer than average for the same three-month period from 2003 to 2018. The map is based on MODIS data from NASA’s Aqua satellite. Note that the map depicts land surface temperatures (LSTs), not air temperatures. LSTs are a measure of how hot the surface would feel to the touch and can sometimes be significantly hotter or cooler than air temperatures.
As a consequence of a strong polar vortex, the polar jet stream—westerly winds in the lower atmosphere that help move weather systems around the planet—stayed farther north than normal this winter. As a result, Francis noted, Pacific storms hit places like Washington and British Columbia while depriving the Sierras of snowfall. Atlantic storms, meanwhile, pummeled the United Kingdom and northwest Europe, but avoided parts of Central and Northern Europe.
NASA Earth Observatory images by Joshua Stevens, using data from the Level 1 and Atmospheres Active Distribution System (LAADS) and Land Atmosphere Near real-time Capability for EOS (LANCE), and MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kathryn Hansen.
