Although mostly settled, a range of possible smaller problems may still exist in the snowpack that could have poor consequences if you do not judge the terrain carefully.
The Aspiring region is very large, and there is very limited data. Caution should still be taken, particularly in steeper, more extreme terrain where unknown weaknesses may exist
Currently, there is 20- 40 cm of very light dry snow overlying a slick rain crust, which is the perfect ingredient for loose dry avalanches. South aspects above around 1500m will be particularly prone to these.
Storm and wind slab formed out of the last storm may still exist at higher elevations above around 1900m on south and east aspects. More likely to be found just under ridgelines, around rock features or sharp roll-overs.
Northern aspects have recently been loaded with fresh snow and will likely go through a cycle of loose wet activity on steep north facing slopes during the middle of the day. Avoid travel under such slopes if you feel things are warming up and you see signs like rollerballing on the snow surface.
On the 25th, around Mt Armstrong, multiple smaller (sz 1) natural wind slab activity was found across NW and W aspects around Tt Armstrong above 1600m. Further south, around the Grant Glacier, a size 2 avalanche was triggered by ice fall at 2000m. This appeared to have stepped down through multiple storm layers. A few other storm and wind slab avalanches were observed to have run out of the last storm on southeast aspects above around 2000m. A size 1 wind slab was also triggered at 2100m also on a southeast aspect by a skier on Sunday also near the Grant Glacier.
If you see any recent avalanche occurrences or have any relevant snowpack information or photos, you can share them via the Public Observations link on the NZAA home page.
Between the 23rd and 24th of July, 50- 60 cm of new snow fell above 1800m. Below 1800 m, a significant amount of rain has soaked the snowpack before temperatures started to cool early Friday morning and finished with about 20cm at around 1300m. Strong north-west winds may have redistributed much of the new snow in exposed areas during the storm and then again by south-west winds early Friday.
Before this, gale westerly winds mostly stripped west aspects back to hard ice or rock and loaded east aspects above 2000m with 1-2m of dense snow. At around 1800m the snow depth was around 50-70cm and was capped by a supportive rain crust before the last storm.
Although the pack appears consolidated, the Aspiring region is very large, and there is still very limited data. Caution should still be taken, particularly in steeper, more extreme terrain where unknown weaknesses may exist.
Forecast for Tuesday
Cloudy periods, with isolated showers developing towards evening.
Wind at 1000 metres Light.
Wind at 2000 metres Southwesterly 30 km/h, turning to northwesterly 40 km/h in the evening.
Wind at 3000 metres Southwesterly 45 km/h, turning to northwesterly 50 km/h in the evening.
Freezing level 1700 metres, lifting to 2100 metres in the evening.
Issued: 1:03pm Mon 27 Jul
Mostly soft conditions however be aware that below around 1700m on all aspects a slick rain crust may be hiding just under the surface.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
