Gale Northwest winds have had a real impact on the snowpack. Now, with the Southerly change, the hazard has moved to the Northern 1/2 aspects.
Conservative approach is recommended in the next few days, if venturing into steeper terrain.
A rising freezing level and solar input into fresh snow will increase the risk of Loose Wet avalanches. Be aware of steep sunny faces in the heat of the day. Rollerballing is the first sign that the surface is warming up. Be mindful of steep sunny slopes above especially when travelling uphill.
With the wind change to South/Southwest these slabs will swing around the compass to Northern1/2 aspects. With such strong winds Slabs will form much lower down slope from the ridge. Watch for dense pockets of wind blown snow if in terrain above 35degrees, above 1600m.
Western aspects above 1800m have a stout, 5cm rain crust buried up to 50cm below the surface. Below this crust, large Facets have formed (Sugary like crystals) This layer produces very easy propagating test results. Because the rain crust is very supportive, it is unlikely to trigger under the weight of a single skier. However heavy loads, like 4-5 humans in one spot or a small avalanche might just be enough load to trigger this layer and it could go quite big. This is a layer to monitor over the foreseeable future and it is possible for the rain crust to become weaker over time increasing the likelihood of waking it up. These types of avalanches are difficult to predict so be very mindful if skiing steep Western aspects above 1800m
Multiple Wind Slabs triggered with explosives today during control work at Porters and Mt Olympus. 31/07.
Several small Wind Slabs reported from control work at Porters, Broken River and Craigieburn Valley, 01/08
Coverage is very patchy with significant pockets of wind deposited snow all the way through to very thin patches. Gale Northwest winds have are hammered the snowpack during this latest storm. The Southwest change began around 19:00 Friday evening and began snowing with cold dry snow. This new Southerly snow came in initially with out much wind, so there is a density change along with a thin layer of weaker snow within this storm snow.
Sunday: Partly cloudy. Westerly winds increasing to gale in the evening. Freezing level 1000m gradually rising to 2000m in the evening.
Monday: Partly cloudy with isolated showers, clearing in the evening. Westerly gale easing and turning Southwest in the evening. Freezing level 1600m lowering to 800m at night.
Wind stripped areas and exposed ridges will be very firm. Ice axe and Crampons are recommended if venturing out.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
