Spring Snowpack
18th March 2021
Covid -19
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This blog is intended to provide hazard and mountain condition information to help plan safer mountain trips.
It was very much a spring feel in the Northern Cairngorms today with a temperature of plus 6 degrees Celsius on Cairngorm at midday. As might be expected the snowpack is soft and moist at all elevations, although it did firm up a little overnight.
Tomorrow any refreeze of the snow surface is likely to be very limited and the snowpack will remain soft and moist. At lower elevations the cover is patchy, and will continue to become more depleted. Due to the mild temperatures the snowpack will continue to consolidate and will remain well bonded.
Cornices will remain prone to collapse where they are drooping over corrie rims. In addition there are some glide cracks starting to appear on crag aprons and at the base of some gullies as the snow starts to creep. These will continue to develop and widen. Although these are not a specific avalanche hazard per se, they may present a hazard to unsuspecting skiers dropping in from above.
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Lenny Cowieson
18th March 2021 7:06 pm
An interesting comment re cooling rates of granites, it is believed that some of these granites crystallised at depths of up to 15 km below the existing land surface, with slow cooling formation of large crystals ensuing.
ncairngormsadmin
19th March 2021 9:23 am
Thanks Lenny, I hadn’t heard of 15km before but I do remember there were different theories as to the depth of the pluton. As I understand it the slow cooling at depth is what creates the porphyritic texture with the larger crystals (phenocrysts) cooling first. I think of this as being similar to the kinetic growth of facets in the snowpack. These are very different processes, and they are purely linked my my romantic notions! Interesting stuff though.
Lenny Cowieson
20th March 2021 10:20 pm
Absolutely spot on with slow cooling giving rise to larger phenocrysts, I can see the analogy with kinetic development of persisting weaknesses at depth in snowpack