‘Dust On Crust’ Concerns Avalanche Forecasters
Avalanche forecasters for the New Zealand Avalanche Advisory (NZAA) are increasingly concerned about upcoming weather
conditions. With a long period of warmer weather and a big dump on the way, conditions are likely to be very tricky in
the backcountry said Mountain Safety Council (MSC) spokesperson Mike Daisley.
“We’ve had long fine spells and a shallow snowpack in early winter. Chatting to our forecasters around the country they
are very concerned about it.”
The forecasters note that there is cause for concern that the conditions have set up trouble later in the season thanks
to the strong temperature gradients that develop within the snowpack promoting faceting or re-crystallisation of the
snow grains.
Daisley said that Mountain Safety Council (MSC), who run New Zealand’s avalanche forecast site Avalanche.net (NZAA)
advise that backcountry travel is not advised.
“We’ve got a persist persistent weak layer throughout the Southern Alps that will become reactive with the additional
snow loading that is forecast over the next few days."
Daisley is keen to point out that there are tools available to help with any backcountry trip.
“We run Avalanche.net so people can get a better idea what the risks are before they head into the backcountry.”
“The avalanche forecast is one of several things you need to check or take before you go backcountry”
“If you are untrained in rescue techniques, lack the appropriate gear or have no idea what the conditions are, please
think carefully about why you’re going backcountry.”
Weather forecasts suggest circumstances in the Southern Alps are about to change with the arrival of the next big storm.
Cracking and settlements have been experienced on the main divide and point to signs of instability that have arisen as
a result of heavy snow loading over a rain crust that had a thin layer of very weak snow on top of it.
The surface conditions often known as ‘dust on crust’ are reported to be widespread throughout the Alps east of the
divide. Dangerous avalanche conditions may develop once the 'Crust Facet' layer is buried.
Daisley said that the MSC forecast team advise all backcountry should be carefully planned.
“If you’re new to backcountry snow adventures, then please take extra precautions if you’re going out so you’ll make it
home to your family”
The New Zealand Avalanche Advisory (NZAA) can be found at www.avalanche.net.nz
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