We had long days of atmospheric stability in almost all of mainland Spain caused by a blocking anticyclone that was literally a “barrier” and prevented any type of unstable air from entering the peninsula. Only a few light storms caused by all the latent heat from the ground stood out in a metaphorically deserted panorama.
However, this anticyclone is getting weaker and so, we are expecting a mass of unstable and cold air due to arrive on Friday. This will ignite the wick to a radical change, not only in the field of temperatures (which will decrease more than 10 degrees in just one day in the north), but also in the heavy rains that can cause significant “chaos” in the Pyrenees and pre-Pyrenees.
Cooler air. Just what we need
And it is that this mass comes from the center of Europe, a cold air, but humid, as most of the wind comes from the British Isles and it will fill with humidity. Once it hits the Pyrenees, this air will rise rapidly creating condensation and convection. For this reason, the first clouds to form will be cumulonimbus, storms that will affect the entire Pyrenees and pre-Pyrenees, discharging between 30 and 40 liters per square meter in the area. The first rains will help the drop in temperatures that will drop drastically .
Heavy rains will help the temperatures to drop
After so many days with heat and a dry environment, a large amount of latent heat has accumulated in the soil and the Mediterranean, which will be a trigger when the cold air mass enters. Once these two factors collide, the large amount of water vapor that will accumulate and condense will create heavy rains that will not only precipitate in the Pyrenees but also in the Cantabrian mountain range and the Catalan coast .
Rain accumulations of between 30 and 40L / m2 are expected, and more severe accumulations in the Pyrenees reaching values of 90 liters in this storm. The accumulation will be over 24/36 hours, so it will not be torrential rains (in general) although we do ask for caution in the Pyrenees sector and avoid parking your car by rivers.
The rain will help to cool the environment, and at night the temperatures at 2,400m will reach 0ºC. This means that the snow level can be calmly placed at 2,300 m on Saturday night.
Snow appears in the second phase in high layers
We are talking about light snowfall, it will not accumulate more than 10 cm at an elevation of 2,300 m on Saturday night, and surely the vast majority of snow will melt in the next rains. However, what's surprising is that some places will have a bit of snow during the Summer!
The ground will already be wet in those areas due to all the rains of the day, so we ask passersby for caution as ice formation will be present in those areas.
The Alps are in luck. How does sledding in August sound?
In the Alps, the snow mass will be greater, and it is expected to accumulate up to 50 cm in the next 5 days at elevations down to 2,100 m. The largest accumulation will be at the western end of the Alps, on the French side. The Italian and Swiss areas will accumulate snow, but it will not exceed 20 centimeters, since the winds will be from the East and most of the snow will be stagnant on the West side.
What we would like to point out is that we are in for some heavy rains between Friday and Sunday, so please, be safe over the weekend. We don't mead to scare anyone but we do want to ask all of you to watch out ;)
Who knows? We may be in for more snowy surprises during the month of September.