When will the winter start in the southern Alps?


By meteomorris on 1 December 2015 · 0

It's the first of December and the temperatures are (too) high. November was wet and warm and even though the snowpack in Switzerland is up to four times thicker than normal and even though you could ride some great powder last weekend, the waiting game has begun again. Striking is the lack of snow in the southern Alps. There's no powder in resorts like Prali, Alagna or the French southern Alps. In regions like Süd-Tirol you can only find some 'natural' snow on the glaciers and the Dolomites? Well, pretty green so far.

The more south you go, the less snow you'll find

Records were broken during the winter of 13/14 when storm after storm hit the southern Alps. Same story during the winter of 09/10 and even last season was pretty good. We've seen plenty of shots from snowed in cars and walls of snow. During those winters you almost forget the artificial snow making is perfected by the Italians...

Anyway, there's a reason why they became so good at it. There are winters when Mother Nature just tend to forget the southern Alps. And that's exactly what's happing at the start of this winters eason. Especially the resorts in the southern Alps that aren't close to the main alpine ridge are looking green or grey. Some images:

Some snow in Nassfeld, Carynthia
Some snow in Nassfeld, Carynthia

Just as in Vars/Risoul
Just as in Vars/Risoul

...and Courmayeur...
...and Courmayeur...

...and Livigno
...and Livigno

But the more south we go, the more green it gets.

The Sella Ronda
The Sella Ronda

Passo Tonale
Passo Tonale

Prali
Prali

No snow near the Hossa bar
No snow near the Hossa bar

Artificial snow making is at maximum capacity to open the ski areas for the tourists, but we need at least two necessary dumps before we can ride powder in the southern Alps.

Artificial snow in the Monte Rosa
Artificial snow in the Monte Rosa

What's the reason that there isn't much snow?

A powerful high pressure area is dominating the weather over the Mediterranean since early November. Storm depressions are kept at a distance, and during those rare moments that the storms hit the Alps, well, they came from the north. Storms from the north mean snow for the northern Alps and no precipitation in the southern Alps. The clouds are pushed against the mountains on the north side of the Alps, the 'stau' forces them to rise, things will cool down and it starts snowing. The air is dropping on the south side of the Alps. The clouds dissolve and there is no snow fall. Something we can easily see on the snow map of the past six days.

Snow in the north, no precipitation in the south
Snow in the north, no precipitation in the south

You can easily spot the difference when we zoom in. Check out the map from the French southern Alps below. It's still snowing in the north, but there's no snowfall south of the Ecrins. Resorts like Vars/Risoul and the Serre Chevalier will get some snow, but it won't snow at all in Praloup or Isola 2000.

No precipitation in the French southern Alps
No precipitation in the French southern Alps

You can spot the same effect when you zoom in on the Piemonte, Lombardia and the Engadin and the Dolomites. The more south you go, the less snow you'll find. It's pretty unique that not a single storm (except one in the middle of October) reached those areas.

No precipitation in the Dolomites
No precipitation in the Dolomites

No precipitation in Lombardia
No precipitation in Lombardia

No precipitation in the Piemonte
No precipitation in the Piemonte

When will it start snowing???

Statistically, the most snow in the Southern Alps comes down during autumn. Especially the high alpine gets a lot of snow. The explanation is simple. Depressions bring cold air towards the Mediterranean and the mix of the cold air and the warm sea often bring lots of snow. Especially the regions south of the Gotthard and the Monte Rosa get a lot of snow. But not this season. Check out the average precipitation during autumn below.

Average precipitation during Sep-Nov
Average precipitation during Sep-Nov

Even the relatively dry autumn of winter 13/14 brought a huge storm with lots of snow to the southern Alps at the end of November. These dumps are important for the snowpack in the southern Alps. Those storms aren't around for a long time, but bring lots of snow.

Snowfall in November 2013
Snowfall in November 2013

The fact that there's no precipitation right now is quite unique. There are no real dumps and we could be optimistic, but normally the biggest dumps from December to February are for the northern Alps.

Average precipitation dec-feb
Average precipitation dec-feb

But there are exceptions!

During winter of 13/14 a huge amount of snow came down in just 24 hours time. Am Alpensüdhang waren die Niederschlagsmengen ausserordentlich: Die SLF-Beobachterin aus Bosco Gurin im westlichen Tessin hat auf ihrem Messfeld auf 1530 m am Donnerstagmorgen eine Neuschneehöhe von 110 cm gemessen. Die 110 cm entsprechen der Neuschneemenge, welche in den letzten 24 Stunden, also von Mittwochmorgen bis Donnerstagmorgen gefallen ist. Dies ist der dritthöchste Wert seit Messbeginn vor 64 Jahren (1. Rang 115 cm im Jahr 1956 / 2. Rang 111 cm im Jahr 1992). Am San Bernardino auf 1640 m gab es mit 120 cm Neuschnee einen neuen Rekord (2. und 3. Rang jeweils 95 cm in den Jahren 1955 und 1987). (Source SLF) It turned out to be the prelude to an exceptional white winter in the Southern Alps. And maybe that will happen this winter as well. There is a study from 2003 that claims that El Niño years have a positive NAO index in the months of November and December (check out this article about the NAO index). That means either a dry and warm period in the Alps and snow in Scandinavia. The NAO index will be negative from January to March and that means snow and cold temperatures in the Alps.

In other words: there are still a lot of chances for the Southern Alps. There is a small miracle in the form of a big dump, but experience has taught us that such miracles occur more frequently in the south than in the north. Until that snow comes down: avoid the southern Alps, because you won't find any powder over there right now!


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