Avalanche Risk In Canterbury Backcountry Remains High Warns Mountain Safety Council

Mountain Safety Council (MSC) is again urging caution for backcountry users in several South Island areas. Chief executive Mike Daisley said it’s time to consider staying inside the skifield boundaries this weekend.
“The forecasters of the NZ Avalanche Advisory are really concerned about a persistent weak layer in most South Island areas with particular concern for the Canterbury region. The danger this presents is likely to be exacerbated by the large snow volumes due in the next two days. It creates a significant and unpredictable risk to backcountry users.”

Daisley said trampers and hunters who are intending on heading into alpine regions need to check conditions as well “Even after this storm we’re likely to have considerable risk in many areas. If you’re heading into the alpine regions please check avalanche.net.nz before you go”

A large, complex low is expected to move onto New Zealand during Friday. This low and its associated fronts should bring severe weather to many parts of the country. During Friday and early Saturday, a feed of cold rain covers the South Island. “Although snow is unlikely to fall as low compared to the previous event, significant accumulations are still likely in many of the South Island ranges” said Allister Gorman, MetService Severe Weather Forecaster.

“Above 800 metres, 30 to 50cm of snow could accumulate in the North Canterbury ranges, with a metre possible in parts of the Southern Alps, South Canterbury and Otago ranges” said Mr Gorman.

Anna Keeling, an IFMGA-certified mountain guide who grew up skiing in the Craigieburn Range triggered two avalanches on Tuesday the 18th of July “I went into the backcountry, exiting from Porters ski field, and triggered two large avalanches. Known as remote triggering, I triggered each slope from a distance of 40-100m away. I did not get caught in either slide.”

She went on to say “For the past seven years we’ve enjoyed a mostly stable Craigieburn snowpack. This year is not the case. It’s best not to go out into the backcountry at the moment.”

Anna explained what a persistent weak layer is and why it’s an issue currently “A persistent weak layer can form when snow falls early in the season. If that early snow sits around for several cold, clear days, the snow crystal will begin to change (metamorphose) into a larger, sugary weak crystal known as a facet. This year we had snow early and it lingered on most aspects - but only above 1700m. The crystals deteriorated and became extremely weak.”

Anna had a clear message for those intending on heading into the Craigieburn backcountry “A persistent weak layer is not to be toyed with. Ride slopes one at a time and realise that with persistent weak layer’s, it may not be the first or even the fifth rider who triggers the avalanche. Therefore, tracks on a steep slope do not necessarily indicate that a slope steeper than 30 degrees is safe.”

NZ Avalanche Forecaster Brad Carpenter said the problem is not isolated to the Craigieburn range “This issue is widespread and not just in the Craigieburn Range. It has also shown up in the Hutt Range and even as far down south as Queenstown and Wanaka. It is showing up on many different aspects and elevations as well.”

“The best thing to do right now is ski your local ski area and avoid the backcountry altogether. The ski areas employ avalanche professionals who use explosives and other techniques to mitigate the danger from avalanches. Stay inbounds and support your local ski field,” He said

“If you don't understand what gear you need, or what a forecast tells you then you're probably out of your depth. Even experienced backcountry users should reconsider their travel plans right now,” Carpenter concluded.

Daisley reiterated that the best thing to do this weekend is to enjoy the skifields “If you’re itching to get out there and have a go, and why wouldn’t you, head to your local field. Their teams are looking out for you. Each field has a comprehensive set of risk management tools and strategies, unlike the backcountry where you’re making your own decisions.”

For more information on the current avalanche conditions in your region head to the forecast page on the NZAA – avalanche.net.nz – and stay up to date as the forecasts change over the next week. If you’re keen on heading into the backcountry this year make sure you upskill yourself. Head to MSC’s website – mountainsafety.org.nz – and get the details on where you can get the right equipment and avalanche training.

ENDS

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