In the Swiss Plateau, there will be room for sunshine between the clouds today, but along the Alps it will be very cloudy – and there will be some snow in places. Tomorrow, an intermediate high will ensure fairly sunny conditions. Things will get exciting on Wednesday – a warm front is likely to create good conditions for dangerous freezing rain in parts of the Swiss Plateau.
Changeable cloudy start to the week
Last night and this morning, it snowed a little, especially along the foothills of the Alps and in Valais, with some drops mixed in with the flakes at the lowest altitudes. On the Swiss Plateau, it was mostly – limited to a few flakes, if at all –. Today, Monday will be cloudy with some sunny spells. On the Swiss Plateau and especially towards the northern edge of the Alps, there will be a friendly mix of sun and clouds at times during the day. Towards the foothills of the Alps and along the Alps, on the other hand, it will remain mostly cloudy with occasional snow or sleet or rain at the lowest altitudes; clear spells will be the exception. In southern Switzerland, there will be plenty of sunshine thanks to the rising northerly foehn. Compared to the previous days, the temperature level will rise slightly, in the north the partly moderate south-westerly to westerly wind will ensure highs of between 2 and 4 degrees, in Ticino around 8 degrees.
Fig. 1: View of the slightly sugared landscape from the Weissenstein; Source: Roundshot
Intermediate high on Tuesday
It will gradually dry out in the mountain regions during the coming night. Tuesday will start with a few residual clouds or local patches of fog. During the day, the weather will be at least partly sunny, with somewhat more extensive medium and high clouds moving through around the middle of the day. Despite the rather sunny character, highs will fall slightly compared to the start of the week, mainly due to the lack of south-westerly winds. After a rather cold morning with widespread –6 to –4 degrees, only just positive maximums are expected during the day, with another icy day in places in hollows. In the south, however, the weather will be mostly sunny with temperatures of 6 to 7 degrees, which is in keeping with the time of year.
From a meteorological point of view, the middle of the week will be exciting. An initially slightly cloudy night will be followed by a warm front on Wednesday. Due to the relatively good radiation conditions during the first half of the night, temperatures will drop into clearly negative territory by midnight. By the early morning, temperatures will rise again slightly, but in German-speaking Switzerland it will still often start slightly frosty. The aforementioned warm front will bring increasingly widespread precipitation from west to east. Slightly positive temperatures will prevail in a layer between 1000 and 2000 meters, the precipitation falling from higher up will melt and fall into a still supercooled base layer with slightly negative temperatures near the ground – the ingredients for freezing rain are in place (see also the figure below for details). As the following forecast map illustrates, the Swiss Plateau regions east of the Basel-Bern-Lucerne line are particularly affected. Here, dangerous slipperiness must be expected on unsalted roads, on sidewalks and in hollows.
Fig. 2: Precipitation pattern on Wednesday morning according to the UCM model; Source: MeteoNews/UBIMET
In the course of the morning, the south-westerly wind gradually rising with the warm front will mix the air masses and temperatures will also rise in the base layer. The snow line will be between 1700 and 2200 meters in the course of the front, sometimes lower in the inner Alps. Depending on the model, between 5 and 20 mm of precipitation will fall on the Swiss Plateau, while around 10 to 30 centimetres of fresh snow can be expected in the mountains above 2200 meters, with a little more in places in Valais and the Bernese Oberland. By contrast, there will be little precipitation in the far east , with strong to stormy southerly foehn winds in the Alpine valleys. Highs in the Swiss Plateau will be around the 5-degree mark, with almost double-digit maximums possible in the foehn valleys.
Fig. 3: Schematic representation of freezing rain and sleet; Source: MeteoNews
Cold front on Thursday
No warm front without a cold front – this will follow in the course of Thursday. The day will be partly cloudy to very cloudy, with the cold front likely to cross us in the second half of the day, with the snow line gradually dropping from around 1500 to 1700 meters by the evening. In the night to Friday, there should then be widespread flakes all the way down again, although the precipitation will already be decreasing again by this time. With moderate south-westerly winds in places, temperatures will reach between 4 and 6 degrees, with the highest values measured in the morning.
Calm end to the week
After the last flakes on Friday morning, especially in the mountains, the weather will become increasingly sunny during the day. However, the air masses are relatively cold, so that only just positive highs will be reached on the Swiss Plateau, at 2000 meters around –10 to –8 degrees. From today's perspective, the coming weekend should be mostly sunny, especially in the mountains. So nothing stands in the way of another great winter sports weekend, and it will be a little milder at altitude, with highs rising to around –2 degrees at 2000 meters by Sunday. On the Swiss Plateau, however, fog is likely to become an issue again. Temperatures here will be around or only slightly above freezing. On the southern side of the Alps, it will be quite sunny and occasionally foehn-like from Thursday afternoon. It will remain somewhat milder here at 7 to 8 degrees.
Fig. 4: Further prospects until next Sunday; Source: MeteoNews
The content of this article has been at least partially computer translated from another language. Therefore, grammatical errors or inaccuracies are possible. Please note that the original language version of the article should be considered authoritative.