Autumn 2023, which has been exceptionally warm for long stretches, will end with another cloudy and cool November day, with the first meteorological winter day following on seamlessly tomorrow. The snow line rises and then falls again, the first weekend of Advent will be cold and wintry.
Cloudy Thursday with snow and rain
As already announced in detail yesterday, a warm front will bring us gray skies and frequent precipitation today. The snow line will rise significantly from the west, but the snowfall will only change to rain in the north-east during the afternoon. Expect tricky conditions on the roads before then!
Fig. 1: Snow-covered Laufenburg in the morning. Later, the snow turns to slush again.; Source: Roundshot
The coming night will also be often wet, with heavy rain in the west in particular. The snow line will climb to between 1500 and 1800 meters, then begin to fall again in the second half of the night.
Start of the meteorological winter
From a meteorological point of view, winter begins tomorrow, December 1st. The day will bring thick clouds and more precipitation, with the snow line varying between 700 and 1200 meters (lower in the Jura and on the northern edge, higher in the foothills of the Alps). The main focus of precipitation will be along the Alps, although the amounts and intensities in Grisons will still be very limited in the morning.
Fig. 2: Cloudy Friday, precipitation intensification in the southeast; Source: MeteoNews
However, this will change in the course of the afternoon! The reason for this is an intensifying low over northern Italy, with a so-called countercurrent situation developing over south-eastern Switzerland (wind directions varying strongly with altitude). As a result, the precipitation will become more and more intense. Although the air mass itself is not that cold, the effect of the precipitation cooling down means that the snow line eats into lower and lower valley locations by the evening.
Fig. 3: Falling snow line due to cooling precipitation; Source: MeteoNews
It continues to snow in Grisons during the night. By Saturday morning, 50 to 75 centimetres of fresh snow will have fallen on the mountains, locally more. It will also be deep winter in the valleys. In general, colder air will reach the northern side of the Alps again on Saturday night and the snow line will drop to low altitudes.
Fig. 4: 48-hour snowfall forecast until Saturday, December 2, 18:00 UTC ; Source: MeteoNews, Ubimet
More snow, especially along the mountains
Saturday will start on a wintry note, with heavy clouds and snow showers. These will be concentrated along the Alps, where it will snow repeatedly until the evening. In Grisons, the intensity will decrease significantly compared to the previous night, but a few centimetres will still fall here too. In the west and on the northern edge, there will only be isolated showers and long dry spells. The clouds will also clear during the afternoon. It will be cold with only a few degrees above zero at most. In the night to Sunday, the weather will begin to calm down and a high will build up. There is a considerable increase in fresh snow on the mountains, the avalanche danger is acute!
Cold first Sunday in Advent
This one deserves a special mention, because on Sunday the winter sports weather is visually very good! In the lowlands, in the foothills of the Alps and in many valleys, there are initially high fog-like residual clouds, but these make way for more and more sunshine during the day. On the mountains there is plenty of sunshine and blue skies, the abundant powder snow attracts skiers to the slopes and sometimes also to the open terrain. But as I said, the avalanche situation is tricky and even with a lot of experience, there is a considerable risk on tours above the tree line! Good planning is an absolute must! Unfortunately, it is to be feared that we will hear of one or two avalanche deaths in the Alps on Sunday evening.
But this first Sunday in Advent also has its nice sides, of course. Sunshine and crunching snow, plus it's even colder than on Saturday. At many stations it will probably remain slightly frosty in the afternoon – a so-called ice day. In the valleys on the southern side of the Alps, the north foehn will be blowing, as it did on Saturday.
Fig. 5: Outlook for the coming days; Source: MeteoNews
Changeable with a rising temperature trend
The coming week will not be quite so wintry. Monday will still be cold, but the cloud cover will increase again. In the west, there will be some snow or rain in places. From Tuesday, it will be generally changeable with occasional precipitation, but the amounts and intensities will probably remain manageable. Around the middle of the week, temperatures will hover around the 5-degree mark, after which milder air will reach us from the southwest. This trend can be seen in many models, but is not yet set in stone. Nevertheless, it is likely that the second weekend of Advent will be milder than the first.
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