Weather: equivalence between mm of rain and snowfall?

[Christophe]

Exni before doing the tease, it's always good to look at the posting dates and reread the messages above the subject when possible in this case this subject does not even have 1 page so it was not too difficult to read all the messages though?

I just revived the subject because of the heavy snowfall in Tyrol a few days ago ... to compare it to the precipitation from Storm Alex ...

[GuyGadeboisTheBack]

Already given above

There is a factor of 10 to 20 between mm of fresh / powder snow and mm of rain ...

So if what fell in rain at the beginning of November in the south east (500 mm of rain) had fallen in winter in the form of snow, it would have given 5 to 10 m of snow in a few hours!

The 2 m of snow in Tyrol a few days ago is therefore very playful!

Well, no because the more the snow falls, the more it settles until it finally forms ice (and the more it slopes, the more the results will be different). In addition, depending on the temperature, there is "flake and flake". So to calculate all that, eh .... good luck. I doubt that even in the 1920 certificate ...

[ENERC]

Already given above

There is a factor of 10 to 20 between mm of fresh / powder snow and mm of rain ...

So if what fell in rain at the beginning of November in the south east (500 mm of rain) had fallen in winter in the form of snow, it would have given 5 to 10 m of snow in a few hours!

The 2 m of snow in Tyrol a few days ago is therefore very playful!

Well, no because the more the snow falls, the more it settles until it finally forms ice (and the more it slopes, the more the results will be different). In addition, depending on the temperature, there is "flake and flake". So to calculate all that, eh .... good luck. I doubt that even in the 1920 certificate ...

It cannot fall 500mm of rain as snow in a short time because either the clouds are loaded with water and it will rain lower in the mountains or the clouds are loaded with snow and then there is a lot less snow in the clouds.
To have a lot of precipitation, you need warm, humid air that cools down as you go up in altitude. But it will rain a lot before the water turns to snow in the clouds.
At Mont Blanc, 500 mm are reached but over several months. The snow gradually settles down.

[Christophe]

What is the record for fresh snowfall over 24 hours or 48 hours in cm "more or less packed" then?

[ENERC]

What is the record for fresh snowfall over 24 hours or 48 hours in cm "more or less packed" then?

I believe that the recent record in France was in January 2018 in Bonneval (Haute Maurienne).

In 36 hours, near the Italian border, it fell at an altitude of 2000m between 1,50 and 1,80m of snow in Haute-Maurienne and between 1,20m and 1,70m in the south of Haute-Tarentaise.

“We will have had 2,40 m of snow in 48 hours,” said the mayor of Bonneval-sur-Arc (Haute-Maurienne) Gabriel Blanc on BFMTV Monday evening.

There was a big avalanche on the road in the valley:


I went hiking in June and the snow was still very present at altitude (more than one meter at the end of June at 2700m)

https://www.leparisien.fr/societe/savoi ... 489896.php

[Flytox]

For the Pyrenees in 2013, they broke a snowfall record (8.2 m cumulative over the season?)

https://france3-regions.francetvinfo.fr ... 95107.html