This week will be an interesting week for meteorologists and for anyone who loves snow. We can expect the dominating current to turn from the east to the south in less than a week. Broadly speaking, this means that the supply of cold air from Russia comes to an end and we can expect some warm air from the Sahara. This will result in lots of freshies in the first place, but the result in the end is not exactly what we were hoping for. But hey, we still have to wait seven weeks before the Corvatsch will open, so we'll have plenty of time. In this forecast:
When I was checking the webcams on Monday morning, it still looked like autumn in some parts of the Alps, but it also looked like winter in other regions. But autumn is pretty awesome. The water in the sea is still warm (I had some great surf on Monday morning), but the atmosphere is already cooling down. This led to the first snowfall in Austria, the Czech Republic and Slovakia last week. It's too cold in large parts of Europe for the time of the year and the temperature drops below zero dergrees during clear nights. Cold air from Russia arrived in Europe and you can spot that on the map below as the geen area.
The combination of cold air and humidity results in snowfall and it's already white in some places in the east of Austria and on the south side of the Alps.
Tuesday will start with a retour d'est, which will bring snow to the border between Italy and France. I expect it to snow heavily around the Mont Viso. It will also start snowing in the east of Austria later that day. It will be the last spark from the cold air from the east before the weather drastically changes.
The weather will start to change from Wednesday. A storm (the L on the map above) arrives at the Iberian Peninsula. The current in the Alps will turn from the southeast to the southwest between this storm and a strong high pressure area over Scandinavia. The cold air from Russia is blocked and more and more warm air from the North Africa is heading to the Alps. The current is that strong that we'll experience a classic 'Stau/Föhn' situation.
You can easily spot it on the Föhn chart below. The strong current from the south first arrives in the western Alps. This will result in a very strong Föhn wind on the north side of Switzerland and in the French northern Alps.
But the Föhn will arrive in Austria not much later.
The temperature will rise, especially in the Föhn regions on the north side of the Alps (check out the orange regions below). It will remain cool on the south side of the Alps (where the air is forced to rise).
It's no different in the western Alps. It is warm in the French Northern Alps and the Rhône valley (caused by the current coming from the south to southeast), but the temperatures will (temporarily) be pretty low south of the Ecrins.
An active front will arrive in the Alps, caused by the current from the south and the approaching storm from the southwest. Initially it is still on the cold side and it will snow heavily in the French Southern Alps and the Italian Piedmont, later expanding to the Monte Rosa and the south of the Gotthard. The snow line will be at pretty low altitude at first and it will snow heavily above 1500 meters especially on the south side of the Ecrins and the Piedmont. The snow line will rise on Thursday and will end up at an altitude of 2400 meters or even higher on Friday. This storm will still bring lots of frehies to the glaciers around the Ecrins, Mont Viso, the Gran Paradiso, the south side of the Mont Blanc, Monte Rosa and the Gotthard.
The problem with this storm is that it can't move any further to the east. The dominant high pressure area over continental Europe is pretty much blocking everything and the storm can't bring any cold air from the north. What's left is warm air from the Sahara. The temperature of the precipitation will rise and the snow (before it turns into rain) will get heavier. It's not the type of storm we want for some cold and dry powder. Then again, it's only the second week of October and the snow that's coming down right now is about a month too early.
This weekend the temperatures will go back to normal in the Alps and winter will be gone for a while. Only the glaciers profit from the precipitation. And this is how it should be in October. Snow that's coming down in October is too early. It's the snow in November we want.