Lots of snow for the northwestern Alps, but the snowline will be an issue

The developments for next week are quite exciting. With a westerly flow, there are (huge) snow amounts in the model calculations, but to be clear: the snowline seems to become a real problem, especially from Friday on.

In this weather report:

• Quiet start to the week
• Snowfall from Wednesday onwards
• Possible harsh conditions over the weekend

Quiet start to the week

From the north, cooler air is trying to move into the Alps. Currently, the regions on the northern Alpine rim are covered in clouds, but higher up and further south the day was sunny. Tomorrow, we will see more clouds coming in. In the western Alps, it will still remain sunny. In Switzerland, the inner-Alpine higher areas can still expect sunshine above the low clouds, but clouds will continue to move in from the north-west. At the same time, a developing low pressure area over northern Italy will bring some snow above 800 - 1000 metres in the eastern southern Alps.

Tuesday also remains fairly calm. In the western Alps initially still quite sunny, but with increasing clouds from the west. On the northern side of the Alps, some temporary clearings are possible due to light föhn conditions and in the eastern half of the southern Alps we will still see some sporadic snowfall. In the evening, the western Alps will get the first snow. With a maximum of 5 centimetres, it is not much for now, but the snowline will still be around or just above 1000 metres.

More precipitation from Wednesday onwards

On Wednesday, precipitation intensity increases in the north-western Alps, but the Alps are in a warm sector ahead of the cold front, so it is still quite mild even at higher altitudes. Winds increase significantly especially along the north-western edge of the Alps. The snowline is around 1,500 metres according to current calculations, possibly a bit higher in the evening.

I don’t want to go too deeply into the precipitation distribution and amounts yet, as the weather models are still quite different. For the French Northern Alps, some 30 to 50 centimetres seem possible. As things can still shift, I will come back to this in detail tomorrow. For the areas in eastern Switzerland and Austria it is still completely uncertain how much this western circulation will yield. Of course, areas like Arlberg are more in the firing line than the eastern areas, but we still have to wait a bit. Below we see two models that still show a vastly different picture.

Precipitation amounts until Tuesday afternoon according to ICON-EU and ECMWF (kachelmannwetter.com)

Supply of mild air and precipitation from Friday (wxcharts.com)

Rain over the weekend?

The developments for after that are tough. Substantial snowfall finally seems to be on the way again, but the rising temperatures are far from ideal for the lower areas. At the moment, the snowfall only seems to clear the snow deficit in the high alpine regions. But at the same time, higher up it seems to be getting so stormy that avalanche danger will become a big issue.

The cause is an unfavourable jet stream, which brings warm and moist air from the southwest and shoots low-pressure areas at central Europe. By the end of the week, the jet stream seems to be just a little too northerly, but close enough to the Alps to provide quite a bit of precipitation. With a high-pressure area over the Iberian Peninsula, this flow is fed with warm air. In short: rain to possibly well above 2000 metres. As mentioned, things can still change because the models are not yet on the same page. Let us hope that the weather models will limit this possible water ballet for the lower areas in the coming days.

ECMWF and GFS ensembles for Geneva (wetterzentrale.de)

Read also:

• What is a Sudden Stratospheric Warming?
• What is an ensemble forecast?
• What are low- and high pressure areas?
• What is a northstau/nordstau?
• What is a southstau/südstau?
• What is föhn?
• What is a retour d’Est?
• What is the jet stream?