February 2021: very cold first half in Europe and North America
1-15 February 2021
Oberwaldhaus, Darmstadt, Germany
After a mild winter 2019/20, winter 2020/21 brings arctic weather conditions to northern & central Europe.
22 February 2021
11 February 2021
The boreal winter season 2019/20 was the warmest winter season ever recorded in Europe, according to the Copernicus Climate Change Service. With persistent mild weather over Europe, particularly in the north and east, the winter 2019/20 was 3.4 °C warmer than the average winter for the period 1981–2010. The temperature was almost 1.4°C higher than that of the previous warmest winter, 2015/16.
Europeans will also remember winter 2019/20 as having very little snow. For example, in Finland, the south coast (Helsinki area) was almost snow-free over the whole winter, see snow depth in Helsinki with the smallest maximum snow depth ever recorded (Credit: FMI). It was too warm for snow in southern Finland (Helsinki DJF 5.8 °C warmer than 1981–2010 mean). Winter 2020/21 also started mild in Europe, but in January 2021 temperatures started to drop, and on 10 January parts of central Spain saw their heaviest snowfalls in decades. By mid-January, many parts of Europe were blanketed in snow, from Spain up to Russia and from Finland across to Greece. However, most of that snow melted in the second half of January when a series of storms battered western Europe. Only Scandinavia and Russia remained snow covered.
In the beginning of February, north-easterly winds brought cold, arctic air from north Siberia to Scandinavia and further west. The Suomi NPP RGB image from 4 February (Figure 1) shows typical arctic airmass features: cloud streets over open seas and snow-covered land (cyan). Over the Gulf of Finland new sea ice can be seen forming at the coastline (see Figure 2).
In the following days, 6–8 February, the temperature contrast between the arctic air over Scandinavia and northern Europe, and warm air over central/southern Europe increased dramatically, leading to a very dangerous weather pattern (see DWD chart from 00:00 UTC on 7 February), similar (but less severe) to the snowstorm case from December 1978. Several countries, including Germany, The Netherlands, Czech Republic and Poland, issued red alerts for snow/ice (Source: Meteoalarm). Along the stationary front, heavy snowfall (20–40 cm) combined with strong winds, causing chaos on roads and railways.
Figure 3 shows the Meteosat-11 Airmass RGB animation from 6 to 10 February: in total, three cyclones can be seen crossing central Europe, dumping snow on their way, see snow map from 9 February (Credit: Snow Cover extent in Europe). A fourth cyclone was approaching from the west. Because of the blocking cold anticyclone over Scandinavia, all the cyclones took a southern track. Note the bright, white cloud band on 6-7 February over Germany, Poland Ukraine and southern Russia, which is caused by so-called dusty cirrus.
Figure 4 is a snapshot taken from the animation, showing one of the cyclones crossing Germany. On this image, the main conceptual models are marked, such as cold fronts, warm fronts and occlusions. For example, over western Germany, a nice example of a Cold Conveyor Belt (CCB) can be seen.
On 10 February, when the last cyclone of the series passed over northern Italy, skies over UK, Denmark, Germany and the Benelux countries started to open up, leading to a further drop in night-time temperatures. The UK had its lowest minimum temperature since 1995 — Braemar, Aberdeenshire, recorded a temperature of -23 °C (-9.4 °F). In central Germany, a 2 m temperature minimum of -26 °C was meassured (nearly a record).
The Terra MODIS RGB images from 10 February (Figure 5) show similar arctic airmass features to Figure 1 — typical cloud streets over open seas (North Sea) and snow-covered land (cyan and red, respectively). Due to the lake-snow effect, the entire east coast of the UK was snow covered. Patches of snow can also be seen over Ireland. In France, a snow band crossed the country from west to east.
MODIS image comparison
February 2021 starts very chilly in the US and southern Canada
Often, when it is cold in central Europe it is warm in eastern North America and Greenland. However, in February 2021 cold weather also gripped the US and Canada. In the beginning of the month, a severe snowstorm (also called a North-Easter) hit the north-eastern States of the US. Storm total snowfall accumulations were as high as 90 cm in Pennsylvania and New Jersey, 64 cm in New York, 60 cm in Massachusetts and 47 cm in Connecticut.
Figure 6 is the 24-h Airmass RGB composite loop with GLM Group Energy Density product overlaid showing the storm that moved along the US east coast. Note that there was a lot of lightning in the area of the warm conveyor belt over the Atlantic. The animation also shows the formation of a well-defined cold conveyor belt that moved westward during 1 and 2 February. This cold, moist air stream helped to enhance snowfall rates over the north-eastern US, with 5-10 cm per hour occurring at some locations. Product info: Accumulation of GLM Level-2 'Group' energy over ABI's scan duration (10-min for full-disk), inverse-distance weighted over a given area for each centroid point and normalised to have [pJ/min] for all sectors. See User Quick Guide for more information.
In the week 7-14 February, with a break-off lobe of the Polar Vortex aloft, arctic airmasses invaded southern Canada, the Great Lakes and the Great Plains. The Airmass RGB image from 12 February 09:00 UTC (Figure 7) shows the typical green colours for very cold land surfaces over southern Canada (south of the Hudson Bay, see close-up view with synop observations).
The arrival of the arctic air over the area of the Great Lakes can be seen in the sequence of MODIS Natural Colours RGB images, 3-9 February (Figure 8). On 3 February (start of the sequence), the Great Lakes appeared cloud free. Although many bays appeared ice covered (e.g. Green Bay in Lake Michigan), there was a notable lack of ice in the lakes.
On 6-9 February, after the passage of a cold front, typical cloud streets (lake effect) can be seen over the Great Lakes, especially over Lake Superior. Due to the extremely low temperatures, the surface waters of the Great Lakes cooled quickly and ice started to form on the more shallow lakes (especially on Lake Erie). See the detailed, five-day high-resolution VIS0.6 animation of cloud streets over Lake Superior, on the RAMMB/CIRA site.
Figure 9 provides an almost simultaneous view of both Europe and North America, showing the extended snow coverage on both continents. Snow is seen in orange to red hues in the so-called Day Solar (Snow) RGB. High, glaciated clouds take similar shades of orange in this RGB product (but usually more pale orange shades). Lower, water clouds take white to pale yellow shades, providing a good contrast to bare or snow-covered ground. The right half of the image is taken by the Meteosat-11 SEVIRI instrument at 12:00 UTC, the left one by the GOES-16 ABI instrument at 15:00 UTC, both on 11 February. The middle of the images sits exactly half-way between the two satellites (longitude-wise), at 37.5 W.
Snow-covered Great Plains, with significant snow in Texas (e.g. in Austin), seen in GOES-16 Snow/Cloud Layers RGB product, 15 February 2021 (snow in white, low clouds in yellow, high clouds in pink) (Credit: CIRA)
Close-up view of snow-covered Benelux countries seen in Terra MODIS Natural Color RGB, 12 February 2021
Close-up view of snow-covered UK seen in Suomi NPP VIIRS Snow RGB, 11 February 2021
Surface air temperature maps (Copernicus Climate Change Service)
Schneesturm. Glatteis. Winter. (DWD, in German)
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