WeatherBlog 2 2019/20 | Brief cooling in sight

Current situation and outlook

Today, Wednesday, the Alps are still in a south to south-westerly flow that is increasingly turning to the west. The blocking high in the east that has accompanied us for a long time is more or less history and hurricane "formerly known as" Sebastien, a.k.a. storm depression ex-Sebastien, is currently the most important player on the European weather playing field. Sebastien recently had hurricane strength, but has now weakened and lost its hurricane status, which has somehow shaken up the complex system of assigning names to storms. In any case, ex-Sebastien is causing strong winds and generally stormy conditions in parts of Germany and France today and tomorrow.

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500hPa geopotential and surface pressure, Wednesday 27.11. Ex-Sebastien is approaching. We are still on the front side of the trough in a SW flow that is turning more and more to the west. — 500hPa geopotential and surface pressure, Wednesday 27.11. Ex-Sebastien is approaching. We are still in a SW flow in front of the trough, which is turning more and more to the west.

meteociel.fr

In the Alps, it will also tend to be uncomfortable today, although not quite as windy as further north. A cold front attached to Sebastien will bring precipitation from the southwest, which will spread more or less across the entire Alpine region over the course of the day. The snow line will remain fairly high. In the west it will clear up again towards the afternoon/evening, in the east everything will happen with the usual time delay.

Thursday will remain fairly changeable with strong winds - now really from the west, slowly turning to the north - and repeated precipitation in the eastern Alps. In the west, it will snow or rain more persistently with a falling snow line. In the French and western Swiss north-western cones, there could well be significant amounts of fresh snow. However, there is little to nothing underneath...

On Friday, ex-Sebastien has finally moved far enough to the east and the Alps will benefit from a northerly flow on the back of the trough. Significantly colder air from the far north makes its way to us and, particularly in the western Alps, it snows quite a bit in the north. The amounts are not comparable to those of the recent snowfalls in the south, but still! Many ski resorts will be happy about the cold temperatures and will finally make snow on the still green valley runs for the start of the season. In the south, it will remain dry and relatively sunny with north föhn winds.

Relatively white at higher altitudes in the northern Alps too, but too warm for snowmaking with the recent foehn. — Also relatively white at higher altitudes in the northern Alps, but too warm for snowmaking with the recent Föhn winds.

LH

Medium-term and forecast

At the moment, it looks like a brief intermittent high on Saturday and potentially a warm front in the night to Sunday, which will bring precipitation from west to east as the snow line rises. Exactly how this will develop is still subject to some uncertainty. It will probably remain comparatively cold into next week, with snow conditions that are not very exciting in terms of gradients. The blocking high in the west will gradually topple over and the current should then become more zonal again. As a result, the signs would point to an Atlantic influence and westerly weather from around the middle of next week. In general, however, the development is still very uncertain and detailed speculation does not seem too sensible to WeatherBlog at the moment.

The polar vortex, which has been rather disrupted so far, is starting to become a little more rounded at the heights directly relevant to us, but the forecast for the stratosphere still looks very uneven. We will then see in 2 to 3 weeks whether and how the stratospheric warming predicted for the first week of December will affect the lower layers.