There are quite a few people who claim they can smell snow. Whether it really is the Arctic cold air that they can smell or whether Father Frost has lit a scented candle - who knows. What is certain is that something is brewing in the north and when it reaches the Alps, we will all be drowning in snow chaos. At least that's what the weather warnings in all the media want.
We are actually dealing with an exemplary trough situation over Central Europe. While a pronounced high has been in place over the Atlantic for days, an increasingly strong area of low pressure is developing over Scandinavia. Highs and lows are shifting so that they are almost side by side and the strongest pressure gradients (areas where the white geopotential lines are tightly packed) run along a west-east axis (from red to blue). The jet, the weather-determining strong wind band in the upper atmosphere, runs almost parallel to the isobars, i.e. along the lines of equal pressure (or equal geopotential, white lines). Due to the position of the pressure centers (high and low) and the strong pressure gradients, we are therefore in a very pronounced northerly flow, which brings cold polar air to the entire Alpine region, as can be seen in the theta-e map. (Blue field)
Smaller systems and fronts are embedded in this cold air mass...
which brings moisture and precipitation. So will this be the long-awaited, final onset of winter? Will the ski resorts get their base for the season, or will it just be a few flakes and sugared peaks again? The most promising aspect of the current weather situation is the expected northerly flow. Moist air is blown over Germany from Scandinavia until it reaches the Alps or the German low mountain ranges and has to move upwards. The higher it rises, the colder it gets. Colder air can absorb less water than warm air and so our snowy air soon reaches saturation point, where clouds form and precipitation falls.
In typical accumulation areas in the northern Alps...
that are favored by such weather, a meter or more of fresh snow can be expected by Tuesday. How well it will turn out for the main ridge and where exactly the precipitation maximums will be recorded depends on exactly how the warm air dome heading towards the Alps from the west behaves. (The green triangle to the west of the British Isles in the image above, which continues to move southeastwards, see maps at www.wetterzentrale.de/topkarten).
The Alpine valleys will be filled with cold air
Over the next few days, the Alpine valleys will be filled with the cold air from the north that we have already discussed. If warm air now moves over these colder air masses, the warm air will be lifted and, similar to the accumulation effects on mountains, there will be some very heavy precipitation.
The following applies for the coming days: Practice fitting snow chains and only leave the house with full ski equipment. If you don't have skins to enjoy yourself in the contrasting forest during storms, you'll probably have to use your charm and bribe lift operators or make do with a whiteout in the glacier ski areas that are already open.
