PA#4: Update

Today an update on PA#4 with an outlook on the weather for next week, for the Alps as well as the Pyrenees. A few details have changed in the weather models over the past few days, but in general we can say that conditions are improving considerably, especially in the Western Alps and Slovenia. Several snow episodes will follow in the coming days. Later this week it will cool down further and the sun will get some more chances, although initially this will still be in fits and starts.

Half a metre of snow in Slovenia

As expected, a huge amount of snow fell in Slovenia in a short period of time last night. The weather models were pretty much right early on with this snowfall. We see that around 50 to 70 centimetres fell in the Karawanks, with locally even 30 centimetres down into the valleys. Tonight, around 10 to 20 centimetres could fall again, maybe even more.

In the north-west Alps, we saw stormy winds over the past few days. Before the cold front passed over in the northern Alps, it was föhny. Not everywhere it was immediately noticeable by the strong winds, but in some typical föhn corridors it was blowing heavily. The cold front gave the most snow in the north-west Alps as expected. In Austria, it stuck to around 5 to 10 centimetres, but in Switzerland and the French Northern Alps, few places saw more than 15 centimetres. Today started reasonably sunny in the Northern Alps, but more cloudy weather followed later. The same goes for tomorrow.

Tuesday slightly less stormy

First of all, back to the Western Alps. Here, in fact, snow follows today and tomorrow. Around 20 centimetres already today, but more will follow tomorrow, as expected. The low pressure core that will hover over France on Tuesday has weakened quite a bit in the new model calculations, making the flow over the Western Alps weaker as well. In doing so, a bit less snow is calculated, but also importantly, the wind field will be a bit weaker. However, do not expect windless conditions! Certainly higher up it will blow hard. Even so, over both days there will be a fine layer of fresh snow. Higher up, we will see accumulations of 30 to 50 centimetres from the Écrins to the Mont-Blanc massif. Most in the Beaufortain and Haute-Savoie regions. The snowline will remain nicely low due to the presence of cold air.

Vb-low

Another development we see from tomorrow is that (again) a low pressure area will develop over the Gulf of Genoa. This will give snow in the southern Alps again tomorrow afternoon and into the night on Wednesday (and, yes, also again in Slovenia), but due to the northeasterly course this core follows, snow may also fall on the north side in Austria. However, the course of such a low-pressure area (a "Vb-Low") is always very difficult to determine in advance. Surprises may occur, but in this case, the models are not calculating particularly much anyway. 10 to 20 centimetres is in it for most areas, but the most will be for the Julian Alps/Slovenia. Significantly more could also fall here. On top of the snow that already fell here last night, another 30 to 50 centimetres may just fall with tonight's and tomorrow's snowfall until Wednesday morning. The lowest regions may experience some rain, but the snowline will still remain quite low.

Taking a look at the snow forecast map, we clearly see this week's two hotspots. The Western Alps (especially the French Northern Alps) and Slovenia & South Austria. In between, snow amounts remain more limited. While other parts of the Alps keep picking up some more snow, Tyrol (except the areas close to the Arlberg), for example, keeps falling by the wayside. Good tours are still only marginally possible and conditions are not yet anything to write home about, but with the little bits of snow that have fallen and will fall, conditions are improving somewhat. Here, we are still waiting for a serious dump.

Some more sunshine

Slightly more sun follows later in the week, but scattered across the Alps there could still be some snow. Wednesday in the Northwest Alps, Thursday possibly in the Southern Alps (east side) and then mainly in Austria. This snowfall will not provide large accumulations anymore. The western Alps will probably be the first to see a broader clearing on Thursday. In combination with the cold air present and the fresh layer of snow, it will therefore be brilliant conditions. Further details about the end of this week are still a bit uncertain, but the trend seems to become drier and sunnier with temperatures steadily picking up some more.

Snow dump in the Pyrenees

In the comments, someone drew my attention to the huge snowfall in the Pyrenees, so of course I want to discuss this option as well. Indeed, here it is also going to dump tremendously from today, especially in the western Pyrenees, think of areas such as Formigal, Astún, Gourette and Tourmalet. The snowfall is caused by the jet stream being directed full on the Pyrenees. It causes snowfall that may leave behind 1 to perhaps 1.5 metres of snow in two phases with a break on Wednesday.

Most of it is already falling today: about half a metre of snow. Initially to quite low (1000-1300m), but tonight the snowline temporarily rises to around 1500 - 1700 metres. Tomorrow some 10 to 20 centimetres may be added, but more will follow later in the week. Thursday again around 10 to 20 centimetres, but the next wave of snow will follow on Friday. However, a bit warmer air is likely to flow in, so the snowline will probably reach just above 1500 metres again.

Read also:

• What is an ensemble forecast?
• What are low- and high pressure areas?
• What is a northstau/nordstau?
• What is a southstau/südstau?
• What is föhn?
• What is the jet stream?