Stationary blocking pattern causes dry and mild conditions

Except for the extreme rainfall in France and Spain, there has been little to report for a week, especially in the Alps. A powerful high-pressure area over Central Europe brings mild and dry weather. Such a calm phase is not uncommon in autumn, but this year the situation seems to remain blocked for a long time. All major weather models expect little change until at least mid-November. The jet stream, which should bring precipitation and cooler air, is too far north. This results in a lot of precipitation in Scandinavia, with snow at higher altitudes.

Spanish snow above 2500 meters

We have all seen in the news how a cut-off upper low (a cold air mass in the upper atmosphere that detaches from the jet stream) caused devastation in Spain. This upper low is still causing thunderstorms over the Iberian Peninsula today and tomorrow. As expected, some of the precipitation in the Pyrenees and Sierra Nevada fell as snow. This allows us to show a webcam image with fresh snow, while in the Alps the meager snow situation is only getting worse.

Large-scale blocking

The jet stream will continue to bypass Central Europe in the coming week (possibly weeks). The image above show the position and strength of the jet stream on Saturday afternoon. The low-pressure area over Spain is still prominent on the map. Depressions follow the jet stream from west to east, and north of it, we find the cold air. At the boundary, such as in Scandinavia and Russia, snow falls at higher altitudes. Over the European continent, the air pressure remains high (around 1030 hPa) with descending air, resulting in a total lack of precipitation.

Inversion weather

Because the days are shortening and it is mostly clear in a high-pressure area, it can cool down significantly at night, especially in the valleys. This cooling air causes condensation in the form of fog and low clouds. Cold air is heavier than mild air, making this moist cool layer very sticky. The weak November sun no longer has the strength to dissolve it. The result is typical inversion weather with gray valleys and radiant sunshine in the mountains. Higher up, the weather is excellent for outdoor sports, but since snow is completely absent up to about 3000 meters, there will be no winter sports for the time being, except in areas with glaciers and/or snow depots.

Long term: From very mild to mild

The temperature in a high-pressure area depends on the type of air, the solar radiation during the day, and the radiation (clear skies) at night. We are dealing with subtropical air that is mild up to great heights. The freezing level this weekend is above 4000 meters, excessively high for November. At 1500 meters, it can easily warm up to 15 degrees, while the valleys with persistent low clouds will not get warmer than 10 degrees. Next week, the entire air mass will cool down slightly, with temperatures at 1500 meters dropping to around 10 degrees and in some valleys, under the inversion, to 5 degrees with a chance of frost during clear nights. The above map shows the average of the ECMWF ensemble for 10 days ahead. It is clear that the high-pressure area will still be very prominent and that the predictability is high (almost all calculations have the same outcome).

Hopefully, we can bring you better snow news later this month.