It is once again very mild in the Alps this weekend. A major cold air outbreak still does not pop up in the weather charts, but an upper-level low will bring some snow in the southern Alps on Monday and then also on the north side in Switzerland. After that, it will most likely remain changeable. On Tuesday, the föhn temporarily increases in the northern Alps, but a cold front will then bring cooling and some snow again.
Cold morning, higher up warm
Some areas on the north-western edge of the Alps such as Flaine and La Clusaz were able to benefit somewhat from the past snowfall, but as the snowline was pretty high, we only see a snow cover above approximately 2400 meters. Further east, as expected, the intensity decreased considerably. So definitely not a cold front to write home about.
Behind the cold front, it is again increasingly mild. In the valleys, temperatures can drop significantly due to the long nights. On both the north and south sides, this caused some local low-stratus clouds and fog. In the higher valleys as shown on the webcam image of Lech, we see signs of frost. Above that, meanwhile, the supply of mild air makes it less wintry. The freezing level rises to around 3500 meters today. After the fog dissolves, temperatures in many valleys can rise up to 15 degrees again.
Dry weekend
The weekend will also be mainly dry and sunny, for the northern and western Alps especially on Sunday. In the valleys, low-hanging clouds remain possible during the night and morning. On the southern side of the Alps, cloud cover will actually increase in the course of Sunday, which is related to a passing upper-level low from an unusual direction.
Tricky upper-level low
The upper-level low I mentioned in my previous weather reports is causing some uncertainties in the weather models. As you can see on the weather chart above, the cold air bubble (the more yellow colours instead of orange/red) spins from the Balkans into Italy in the coming days and then moves north again over the Alps towards Benelux. Such an upper-level low, especially with this unusual retrograde route, always creates great uncertainty in the forecast, even in this reasonably short term period.
The models do show us fairly unambiguous signals today in terms of precipitation distribution and amounts, but looking at the previous model runs (12z yesterday), we see some quite large differences. So it cannot be ruled out that we will see some differences in the next run as well due to the erratic behaviour of such an upper-level low.
Precipitation amounts for Monday by the GFS, ECMWF and ICON-EU this morning (wxcharts.com)
Precipitation amounts for Monday of the 12z runs of the GFS, ECMWF and ICON-EU models yesterday (wxcharts.com)
All in all, I expect around 5 to 10 centimeters in some regions in the southern Alps such as Ticino and the north side of Piedmont on Monday. With the reasonably cold air present in the southern Alps, the snowline could drop below 1500 meters. In the Swiss Northern Alps, some 10 to 20 centimeters may fall during Monday, locally even a little more. Here, too, the snowline (except for the westernmost areas) drops to around 1500 meters. Graubünden and the regions further east will most likely keep it dry with the expected southföhn. To what extent France can benefit from this snowfall is still uncertain. The areas around Mont Blanc and the remaining northern areas against the alpine main ridge are most likely to get some snow.
Changeable
After that, it seems to remain changeable for the Alps. An approaching low-pressure area increases the pressure gradient over the Alps on Tuesday, giving us south-föhn in the northern Alps. In the evening and night into Wednesday, a cold front will pass with around 10 centimeters of snow possible (possibly more in the north-western Alps) with again a snowline dropping from around 2000 meters to 1500 meters.
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It is once again very mild in the Alps this weekend = it’s once again normal weather in the Alps :). Now anything below 2 degrees above the ‘old’ normal should be considered ’ cold’