New Zealand Mountan Safety Council

Nelson Lakes

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Issued at 22/08/2017 7:47pm. Valid till 25/08/2017 6pm

Nelson Lakes

Mountain
Current avalanche advisory
High Alpine

Above 2000 meters

Alpine

1000 to 2000 meters

Sub Alpine

Below 1000 meters

Avalanche Danger Scale
Avalanche Danger Scale
Report TutorialPrint Reporthear report

Primary Avalanche Danger

Dangerous Aspects
high
Danger Rose
3
Highest Danger Rating
Likelihood
indicator
gauge
Certain
Likely
Unlikely
Size
indicator
gauge
Largest
Small
Trend
indicator
gauge
Increasing
No change
Decreasing
Time of day
clock
Time of day
All day
Alpine level
High Alpine: Above 2000m
Alpine: 1000 to 2000m
Low Alpine: Below 1000m
Description:
Wind loaded snow overlie weaker old snow in upper start zones on eastern and southern aspects in particular. This danger will only exist above 2000m. Care is required on steep south and east facing slopes near ridge crest at upper elevations with the increased load from the storm cycle last week.

Secondary Avalanche Danger

Dangerous Aspects
high
Danger Rose
1
Highest Danger Rating
Likelihood
indicator
gauge
Certain
Likely
Unlikely
Size
indicator
gauge
Largest
Small
Trend
indicator
gauge
Increasing
No change
Decreasing
Time of day
clock
Time of day
All day
Alpine level
High Alpine: Above 2000m
Alpine: 1000 to 2000m
Low Alpine: Below 1000m
Description:
50 cm + or so total storm snow has fallen at upper elevations and particularly in the west. Foot penetration at 2000m is over 50cm on the Mahanga Range. Storm slab has developed with significant additional snow fall on Monday last week. Thursday and Friday last week saw continued significant loading. Extreme care required on eastern and southern aspects particularly above 1900m. There is a possibility of these smaller avalanches being the trigger for identified weaknesses deeper in the snow pack.

Tertiary Avalanche Danger

Dangerous Aspects
high
Danger Rose
1
Highest Danger Rating
Likelihood
indicator
gauge
Certain
Likely
Unlikely
Size
indicator
gauge
Largest
Small
Trend
indicator
gauge
Increasing
No change
Decreasing
Time of day
clock
Time of day
All day
Alpine level
High Alpine: Above 2000m
Alpine: 1000 to 2000m
Low Alpine: Below 1000m
Description:
Winds from the southeast over the weekend saw the available snow redistributed to aspects lee to the southeast at ridge crest above 1900metres. Due to the existing problem of storm slab on the other side of the ridge, careful route finding will be required.This problem is expected to be isolated to the ridge crest and be small in size.

Recent Avalanche Activity

Recent Avalanche Activity
Multiple class 2.5 to 3.5 avalanches on south and eastern aspects. One in the upper Travers Valley has made valley floor and had a fracture line in excess of 3 metres deep. The debris shows these avalanches have failed in the old snow.
Multiple smaller class 1 and 2 soft slabs have been evident on many different aspects from the last storm cycle.
The timing of these is suspected to be during last weekend.13/8/17
Multiple loose wet avalanches on solar aspects on Monday morning.14/8/17

Current Snowpack Conditions

Current Snowpack Conditions
Shallow snow for the early part of the season means that the old snow on the southern and eastern aspects above 1900m is weak. A faceted layer low in the snowpack has been responsible for multiple large avalanches. The snow pack below 1900m has increased in strength somewhat due to being saturated by rain last week then the water draining and the snow pack refreezing.Rain has again saturated the snow pack below 1700m while snow fell to upper elevations in the park. This has formed storm slab. Of particular concern is the snowpack has now been loaded above 1900m where the old snow is likely to still be weak.

Mountain Weather

Mountain Weather
Cloudy at times with a freezing level rising to 1700m during the day then lowering to 1400m overnight. Westerly winds.


MetService
For more information go to: http://www.metservice.com/mountain/index

Forecast by Adrian Briggs

Avalanche Forecast Regions:
Mountain Safety Council managed websites
Mountainf Safety Council websiteAdventure Smart websiteNew Zealand Avalanche Center