We can now provide more details regarding the snow forecast for this exciting week. The main news remains that the Western Alps will receive two significant snowfalls. However, these snowfalls will start with a relatively high snow line, which means the final accumulation below 1800 meters might be disappointing, especially in France.
Cold air slowly makes its way south
Under the influence of a deep depression over Scandinavia, polar air has spread over parts of Europe. This morning, a thin layer of fresh snow was reported in Scotland, the Sauerland, the Harz, and the German-Czech border regions. In the Alps, the snow cover is still well below normal for this time of year despite a few wintery spells. The further descent of the cold is delayed by a low-pressure area over the British Isles, which draws in mild air on its eastern flank. This system will move rapidly through the Netherlands and northern Germany to the Baltic States tomorrow (Tuesday). Behind it, the polar air has free rein, and on Wednesday, it will freeze in Austria and Switzerland above approximately 800 meters. In the French Alps, the freezing level is slightly higher, eventually sinking to circa 1200 meters.
First snowfall for France and Switzerland
On Tuesday morning, precursors of a cold front with showery precipitation reach the Western-Swiss- and Northern-French Alps. It starts snowing above 1800 to 2200 meters, and the snowfall becomes heavier throughout the day. In the evening, the precipitation also spreads over the rest of the French and Swiss Alps. Below the mentioned altitude, there will be a lot of rain. The cold front moves through during the night to Wednesday, after which the snow line drops to the higher valleys (800 to 1000 meters from north to south). By Wednesday evening the snowfall stops, leaving 30 to 60 centimeters of fresh snow above 2000 meters. Because this is a typical weststau, most precipitation will fall in the Western Alps on and west of high massifs such as the Ecrins, Thabor, Trois-Vallées, Vanoise, and Mont-Blanc. It is not excluded that locally 80 centimeters may fall during this dump.
Not a thick cover for everyone
Many valleys will also turn white, but the peak of the precipitation will have passed, leaving a more modest layer. Switzerland has the best prospects because here it will continue to snow the longest, and the polar air will arrive first from the north. East/south of the main ridge, much less snow will fall, and in various Italian areas, it will likely remain mostly green. In the Alpes-Maritimes, the cold air arrives last, and the precipitation is less intense. Here, a maximum of 20 centimeters will fall on the peaks, and it will remain predominantly green below 1500 meters.
Austria’s turn on Wednesday night
Apart from France and Switzerland, where it can snow for more than 24 hours, Austria will also get snow. This happens when the flow behind the cold front becomes northwesterly, and the cold air is already in place. On Wednesday night and Wednesday morning, we can expect 20 to 40 centimeters above 800 meters in Tirol, Salzburg, and western Styria. In Vorarlberg, 30-50 centimeters is likely. Elsewhere in Austria, less snow will fall; south of the main ridge, there is little going on, and in Carinthia and the southern part of Styria, hardly any snow will come down.
Strong wind but less severe than previously expected
The stormy weather around the cold front has fortunately decreased in the model output. At 2500 meters in the French and Swiss Alps, the wind peaks between Tuesday evening and Wednesday evening at 6 to 7 Beaufort with gusts around 80 km/h. There will certainly be drifting snow on wind-sensitive slopes, but a real snowstorm will not occur.
Thursday: New Round, New chances
On Thursday, a new low-pressure area will move over southern France and northern Italy with again a lot of precipitation. A very different situation on the weather maps than Tuesday and Wednesday, but for Switzerland and France, probably a similar snow scenario. Again, we start with milder air from the south, causing some precipitation below 1500-2000 meters to fall as rain, especially in the French Alps. Eventually, it will cool down, turning many valleys white by Thursday evening, but the snow cover will be much more limited than in the high mountains. Most precipitation is again expected in the Western Alps, with 30-40 centimeters of new snow above 2000 meters in the same regions as Wednesday. Because the disturbance also moves over Italy, the Southern Alps will likely finally see some flakes. However, a serious snow cover of more than 10 centimeters is probably not in the cards. Also not for Austria, except for Vorarlberg, where possibly 20 centimeters of fresh powder will fall.
Friday transition day in cold air
On Friday, the sun will peak through here and there on the approach of a high-pressure ridge. In the morning, some snow may still fall here and there. It will be the coldest day of the week with afternoon temperatures around -8 at 1500 meters and -18 at 3000 meters. There is little wind, making the conditions optimal for enjoying the freshly fallen snow. Pay attention to the current avalanche warnings that will undoubtedly be issued for the high mountains. Saturday will also be dry and calm. It will warm up quickly, with temperatures at 1500 meters becoming slightly positive again.
Mild weather from Sunday onwards
Unfortunately, the warming continues. The cause is a deep depression near Ireland that allows subtropical air from Africa to flow over the continent. From Sunday, there will be a strong southwesterly flow with very mild conditions in the upper atmosphere, especially in the Western and Northern Alps. The air is initially still dry, and in the inner Alps, the impact on the snow cover will be limited. The weather maps for next week do not look entirely hopeless; there are three scenarios:
- High pressure over the Alps with night frost and dry thaw during the day (slow snowmelt)
- New depressions with mainly Tuesday and Wednesday precipitation with a high snow line
- Again (slightly) colder air from the north with a bit of snow and fairly low temperatures
We will keep you updated this week with more details about the snow forecast for Thursday and the long-term warming.
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##flakenews
;-)