We are coming in December which also means entering the meteorological winter! This year, December is set to get off to a cold and hectic start. A bit like the image of three years ago in 2017, although every situation is never the same ...
The weather will change from Tuesday afternoon with the arrival of a disturbance from the north, driven by a cold drop in altitude (-30 ° c to ~ 5500m and -4 ° c to ~ 1500m). This disturbance will be of low intensity with a rain-snow limit which will drop to 1000m on Tuesday evening.
Wednesday morning, the cooling will be important under the influence of this cold drop and it will snow until the Pyrenean foothills, in the form of showers from 500 / 600m. No large quantities to expect, with ground resistance from 700m and cumulative amounts which should be around 5 to 10cm above 1000m, or even 15cm, especially on the Ariège side. These flurries will gradually subside on Wednesday afternoon. Note that the ends of the chain will rather stay apart. The tramontane will blow between 60 and 80km / h in its domain.
Thursday will be a day of transition between two disturbances. A little warmth will occur with a 0 ° C isotherm rising to 1900m in the afternoon. The sky will be divided everywhere between clouds and clearings.
From Friday, the famous descent of maritime polar air that we spoke about in the previous article, will land in the country. This should bring some winter hustle and bustle into the entire weekend. However, the deadline is approaching and many uncertainties are still relevant, especially regarding the accumulation of precipitation and snow in the mountains!
This polar descent indeed gives a hard time to our models! The placement of low pressure excavation in the British Isles is still poorly understood and secondary excavation in the Mediterranean over the weekend remains possible.
All this will therefore have repercussions on the sensitive weather in the Pyrenees with more or less heterogeneous rainfall.
We retain two scenarios for the moment:
The first sees a northwesterly flow penetrating enough inland which would cause heavy snowfall in the mountains up to fairly low altitude (~ 800m). The western Pyrenees could experience significant amounts of snowfall in the mountains: 50cm to 1 meter of snow. But these accumulations would be clearly decreasing by going east with no more than 15cm at Font-Romeu, for example.
The second scenario envisages much more modest and scattered snowfall until the weekend with around 10 to 20cm generally on the massif. The dynamism would indeed be pushed off the ocean in this context.
Within 48 hours, we will normally have more information to anticipate this first real winter assault of the season.
See you soon…The Pyrénées Weather Team