WeatherBlog 19 2020/21 | End of the March winter

Current situation and outlook

The graphic on the right provides a reminder of the large-scale structures that have kept us busy over the past two weeks. The striking low-pressure area to the east of the Alps was still directly over the Alps last week and was responsible for the very pleasing amounts of snow in the north. There is still an equally prominent high wedge to the west of the low pressure system, which is effectively blocking the zonal flow over the Atlantic and deflecting it to the north. This type of weather pattern is quite persistent, as has been mentioned many times before. When the waves are this big, they shift only slowly and remain almost stationary over a longer period of time.

But gradually they do shift and our low has now moved so far downstream that it no longer has any control over the weather in the Alps. High pressure takes over. However, the blocking high pressure will also change over time and will neither stay in exactly the same place nor remain as strong forever. As a result, minor disturbances will pass through again and again over the next few days and the sunshine will be somewhat clouded. It will start on Thursday with a shortwave trough crossing the Alps from the west, which will probably only result in slightly cloudier skies, more so in the north than in the south. As slow as the big waves, as fast as the small ones - the trough, which is tiny compared to the dominant waves of the last few days, will quickly dissipate and Friday will be widely sunny again. On Saturday, a cold front will cross from the NW and bring a few snowflakes, but probably no significant amounts of fresh snow. From Sunday, a few sunny, much warmer days are on the horizon. The development in the forecast is open and more or less all options are still possible, including cool, snow-friendly conditions in the mountains.

A comparison of the many stations shows that, as expected, snow depths are falling at almost all stations. However, the decline varies from region to region and is not happening at the same rate everywhere. The differences are not only due to altitude, but also occur between the northern and southern side of the Alps, for example. The authors of the study identify 5 regions in which snow depths are developing similarly. The greatest losses are recorded in regions in the Southern Alps with less snow from the outset and in the regions and altitudes where the snow cover disappears completely because the precipitation falls almost exclusively as rain. The results of the study are basically not surprising and underpin the known, decreasing trend, as well as the comparatively pronounced regional differences in snow. What is remarkable and very pleasing is the comprehensive data set that has been created by this study, most of which is also made freely accessible. More of this please!