Today still warm, then snow from the west

The past few days, the Alps have been under high pressure, which has ensured calm and very sunny autumn weather. Also today it will be another day with beautiful autumn conditions. During the weekend we can expect a split with the first snowfall in the (South) Western Alps and at the same time warm conditions in the Northern Alps with a powerful Südföhn. After the weekend a second cold front will follow, which will also affect the Northern Alps.

Südföhn

^Föhn
Read here everything about föhn.

Before the snow reaches the Alps, we will first be in the warm sector. In the course of today, a strong Südföhn will come up with the southwestern high flow, which will make the temperatures in the Northern Alps rise considerably. The frost line will rise to well above 3000 metres and temperatures of 15 to even 20 degrees may be reached in the valleys in the coming days.

Precipitation in the South-West Alps

While Switzerland and Austria will still be dealing with a strong Südföhn tomorrow, the cold front will approach from the west. Due to the föhn, the weak front will not bring snowfall on the northern side of the Alps yet, but in the French Southern Alps and the Western Italian Alps, a portion of moist air from the Mediterranean will bring some snow higher up. The mild flow will keep the snowline in France around 2500 metres. In Piemonte and Ticino, Saturday will bring some cooler air masses, which will bring the snowline to just below 2000 metres, but on Sunday the snowline will rise again. In the higher areas, some 20 to 30 centimetres of fresh snow is possible until Sunday night.

Cold front passage

In the night from Sunday to Monday, a new cold front will reach the Western Alps. The föhn flow will be destroyed this time and so it will also start snowing in the Northern Alps. On Monday during the day, the precipitation will also move further east across Austria. With the arrival of cooler air, the snowline on Monday in the Northern Alps will drop towards 1500 meters and locally even a bit lower. In the Southern Alps there is still some warmer air present which will keep the snowline around 2000 meters. On a large scale, about 20 to 40 centimeters of snow is possible in the higher regions. In the Julian Alps, convergence may bring even more precipitation (possibly more than 100mm), but here it will remain mild for a longer time, which may keep the snowline at 2500 metres (or even higher) for a long time.

More snow?

In the middle of next week, under the influence of a new low pressure area and cold front from the northwest, there might be snow again. The snowline on Thursday may even reach around 1000 metres in the Northern Alps, but as it is still quite far away, I will give a detailed description of that snowfall on Monday.