Rapid snowmelt in the North

Following a very snowy winter, with record snow depths in several places, more than half of Troms and Finnmark has melted free of snow in just a couple of weeks.


In these maps white indicates snow-covered and green snow-free land. The red line shows the Troms and Finnmark border.

The maps show the snow cover for Northern Scandinavia on May 15, June 1 and June 15. At the beginning of the summer month June, almost 90% of Troms and Finnmark county was still covered by snow, but only two weeks later, the snow-covered area was down to 40%. The remaining snow is located in the mountains, so while the lowlands are green and summery, good skiing conditions are reported in several places in the mountains. In Tromsø, among other places, the ski enthusiasts have been pleased with the combination of summer heat and skiing.

Photos: Merethe Samuelsen, Tromsø, 13 June 2020. On skiis: Nils Henrik Fause.

 

The figure below shows the ratio of snow-covered land for Troms and Finnmark from 2016 until June 19 2020. Each year is given by a separate colour. This winter and spring (black curve) stands out for having a late start to the snowmelt, followed by very fast melting.

 

Satellite monitoring of snow cover at the Norwegian Meteorological Institute

Both the snow maps and the snow cover figure above are based on satellite measurements made with optical instruments. To derive snow cover from this type of instrument, the sun must be high enough in the sky as the satellite passes overhead. Therefore, these snow maps are not available in winter, which is indicated by the grey areas in the bottom figure. The optical instruments cannot see through clouds. Most days, larger or smaller parts of the country will be cloudy. Therefore, in order to calculate the proportion of snow-covered area, cloudless mosaics are created, which means that for areas that are cloudy in today's map, these are filled using data from the most recent cloudless map. The snow maps shown in this case are such cloudless mosaics. Read more about the snow maps here and the snow cover figures here.

Tags: