WeatherBlog 17 2017/18 | Cold front, sun, south föhn

The cold front is being produced by a low with a core off Scotland and is approaching the Alpine arc from the west. Accordingly, it will get wet earlier in the west and dry again earlier - in the eastern Alps it may snow until late into the night, but it will start later.

Outlook

A new Atlantic low will take over over the next few days: a trough will form off the coast of France and Portugal from the remnants of Friday's nor'easter (see below), which will keep us busy until the weekend. Thursday and Friday will be relatively friendly with a weak intermediate high influence, although more compact clouds are likely to be present from time to time. During Friday, the current will turn to the southwest due to the aforementioned trough. This is associated with a general rise in temperatures and the familiar mixture of foehn in the north and accumulating precipitation in the south. The latter may well turn out to be heavy and the snow line may become problematic - we're familiar with that too. If a PowderAlert is issued for the south, the oracle will certainly announce its prophecy in good time.

This type of severe, cold, snowy low is typical for the east coast of the USA and can only develop in this form on the east coast of a continent, from a polar cold air outbreak and the relatively warm ocean to the east of it. If a trough filled with cold polar air forms in the eastern half of the North American continent, the chances are pretty good that it will slide a little to the east with the prevailing westerly drift in these latitudes and reach the Atlantic. There it can soak up moisture and unload it from the north-east (hence the name Nor'easter) onto the east coast.