Snow and low humidity / dewpoint

[Lake District Blizzards]

Interesting observation today - Great Dun fell has a good covering of snow above 1500ft on the top like many other mountains in Cumbria,

the temperature today reached 10.5c at 2800ft obviously with blazing sunshine and very little wind.

The Dewpoint mid-afternoon was -16.3c giving a humidity reading of 13.5%

Now down at this altitude, even a foot of snow would melt within about half an hour under blazing sunshine and 10c

Is the low humidity and resultant dewpoint the main factor in preserving the snow in such high temperatures? What is the warmest it could get before you ended up with a rapid mega melt?

[cheeky_monkey]

i think so..here in Edmonton Canada the air is often very dry..for example we had a period in mid February when the temperature exceeded 10c 6 days in a row with a record high of 16.5c on one of those days..yet the snow only melted very slowly and by the end of that period i would say we still had close to 75% snow cover 

Edited March 27, 2017 by cheeky_monkey

[damianslaw]

On 25/03/2017 at 22:14, Lake District Blizzards said:

Interesting observation today - Great Dun fell has a good covering of snow above 1500ft on the top like many other mountains in Cumbria,

the temperature today reached 10.5c at 2800ft obviously with blazing sunshine and very little wind.

The Dewpoint mid-afternoon was -16.3c giving a humidity reading of 13.5%

Now down at this altitude, even a foot of snow would melt within about half an hour under blazing sunshine and 10c

Is the low humidity and resultant dewpoint the main factor in preserving the snow in such high temperatures? What is the warmest it could get before you ended up with a rapid mega melt?

Yes I've noticed how the snow is holding well particularly on eastern faces, where the suns strength in the morning hasn't quite been enough to result in rapid melt, I suspect the very dry air and low humidity is the key reason, in saturated air and temps 3/4 degrees snow quickly melts. With a change in airstream, tomorrow should result in rapid snow loss with humidity levels rocketing as the miserable tropical maritime air invades.