After a few days with winter temperatures and snowfall into the valleys, a strong westerly current provides the supply of considerably warmer and humid maritime air from Thursday. So we have to take a rising snow line in the Alps into account. The higher areas in the Western and Northern Alps are good with a meter of snow on a large scale, but below 1500 meters a lot will come down as rain. Due to the snowfall in combination with the rapid warming and a stormy wind, the avalanche danger will rise again.
Today the day starts with snowfall in the Western Alps. The sun can temporarily show itself between the snow showers. The sun continues to come out in Austria until the afternoon, but here it will also start to snow in the course of the afternoon. With nice winter temperatures, this snow falls into the valleys and a total of 10 to 20 centimeters of snow can fall for the northwestern Alps. With the exception of the Julian Alps, it remains dry today in the Southern Alps and it clears from the west.
The Western Alps won't be cloudy anymore for the most part tonight, but on the north side of the Alps it can still snow all day tomorrow. Today and tomorrow, a total of 20 cm to possibly even 30 centimeters can fall in the 'Stau areas'. Especially regions such as Allgäu and Dachstein can hit the 30 centimeters.
Just as the snowfall in Austria decreases, new snow will follow for the Western Alps in the night from Tuesday to Wednesday. The warm front causes slightly rising temperatures, causing the snow line to rise to about 800 to 1200 meters in the course of Wednesday. In Austria, despite the rising air temperatures, it continues to snow into the valleys. The warm front is a prelude of what the Alps can expect from Thursday.
The models had already been showing the possibility of the supply of warm air in the weather maps for almost a week, but now it is certain that we will have to deal with this weather change and a rising snow line. Due to a strong westerly current, the upper air temperatures will rise by 10 degrees from Wednesday. Until Thursday morning the snow line in the Western Alps will remain somewhat low, especially in the inner alpine valleys, but in the course of the afternoon and especially in the night from Thursday to Friday the wind will increase and the Western Alps will have to deal with temperatures up to 5 degrees at an altitude of 1500 meters, which means that the snow line will temporarily be around 2000 meters.
Austria avoids these high temperatures for a longer time due to its more easterly location. Thursday, the inner alpine valleys can benefit even longer from a lower snow line due to the process of precipitation cooling. Here it can snow for a long time into the valleys, but further north the snow line quickly rises to about 1500 meters. There could be a possibility that, especially in the northern areas in Vorarlberg and Tyrol, it can temporarily rain up to about 1800 meters Friday morning.
For the higher parts of the Northern Alps, it means they will get hammered. From Wednesday to Friday, the precipitation phases could bring over half a meter to even a meter in the northwestern Alps. Further east, the quantities decrease and I expect about 30 to 50 centimeters of snow for the high alpine.
The uncertainty in the models from the weekend is very high, so looking further does not make much sense. To give an idea of the uncertainty, you can see the two different 00Z runs of the ECMWF and the GFS this morning above at the same time (Saturday 12 UTC). While the European model temporarily cools the Northern Alps considerably with an Arctic outbreak from the north, the GFS model foresees this outbreak further east, allowing a depression over the Atlantic Ocean to move east at a rapid pace and again a large portion of warm that can land in the Alps. Wednesday more about the developments for the weekend! Hopefully also with maps of our own forecast.
Winter is here, but it's still not sure what this season will look like. It's always time to start dreaming and preparing. Whatever it will look like, the wePowder Guide is available again. We've extended the pre-order price of € 45.00 (excl. shipping) for a while. This thick book of 400+ pages is in stock and will be delivered to you as soon as possible! Thanks for your support!