We've started week two of SNOWvember which seems to be following a classic pattern. Autumn is traditionally a period with a lot of precipitation on the southern side of the Alps. Almost every season a thick pack of snow comes down. At least if the snow line cooperates a bit and we don't just see rain far into the high alpine.
With a traditional November pattern, the jet stream has a slide to the west of the Alps. This transports cold polar air to Spain and the Mediterranean. This cold upper air comes in contact with the still very mild seawater of the Mediterranean. The combination of a polar upper air, a still warm Mediterranean sea and the presence of a lot of moisture guarantees a lot of energy.
The result is the creation of a powerful low-pressure area that continues to feed itself through the continuous supply of cold air from the north and the moisture of the Mediterranean. In this case it is storm Detlef. This mainly has the character of an Adria-low and will be located near the eastern Alps.
Detlef is focused on the eastern Alps on Tuesday and Wednesday and in particular the main alpine ridge and the areas south of it. A lot of moisture is pressed against the southern side of the Alps with a strong southern flow. Cold and warm air are quite close to each other. It is the mild air that ensures that the moisture can penetrate far into the Alps and can even go far beyond the main alpine ridge. It is the cold air that comes from the west that simultaneously pushes down the snow line. Last but not least, the intensive precipitation caused by the dam wall that's called the Alps results in strong orographic cooling. The result is a lot of snow, as in: a LOT of snow. The snow line fluctuates between 600 meters in the north and southwest of this part of the Alps to 1700 meters and higher in the east.
After Wednesday, Detlef loses its grip on the Eastern Alps, but a new storm is already warming up.
The Alps will get hammered by a second storm on Thursday, or better called a storm complex west and southwest of the Alps. The most important factor in this case is the Genua-low, which is created from Thursday. To the west of the Alps, polar air is transported back to the Mediterranean Sea. Then the same story follows: cold air, warm sea, lots of moisture and then: KABOOM. And with KABOOM I mean another strong Mediterranean sea storm that pushes a lot of moisture against the Alps with a southern to southeastern flow.
The result is a lot of precipitation for the western Alps and in particular the south side of the main alpine ridge where parts of the precipitation passes over the main alpine ridge to France and Switzerland. Such a Genoa-low is also called a 'retour d'est' and I would definitely recommend this article to read more about this phenomenon.
Because it is only Tuesday, it is difficult to say exactly where the center of gravity of the snowfall from Thursday will be. But well-known regional snow magnets with snow from southeast to south are the Gotthard, Monte Rosa-Simplon, Gran Paradiso, Haute Maurienne and the areas around the Mont Viso.
Normally I would do some more research where most of the flakes will fall, but that is not necessary for now. It is only the beginning of November, the snow cover is still thin, many areas are still closed and the off-piste is still full of surprises Only when we have completed this week's storm cycle and the storms of thee coming weekend will I take a critical look at whether I can convince myself of a trip to the Alps. That will be the weekend of November 22nd at the earliest.
Even after Thursday's storm, it will continue. A third storm is planned for the southern side of the Alps for the coming weekend. For now, this is calculated as Adria-low, which produces the most snow in the east. But next weekend is still very far away. I can see that the third storm is coming, but the exact position (Adria or Genoa-low) will become clear in the coming days.
If we look even further into the future, the most important weather models also outline a fourth and fifth storm for the third week of SNOWvember, with which the high alpine will be completely covered with snow.
But it looks like this SNOWvember will provide one of the better starts of the winter for the high alpine. A thick layer of snow is a solid base and with a little luck we won't (or much less) have to deal with faceted snow deep in the snow cover.
In between the lines you can read that I am positive about the start of the winter. A good base above the tree line is coming up and that makes me happy. But on the other hand you should be aware that it is still pre-season.
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Stay stoked, Morris