A large amount of snow is forecast through Thursday on top of the heavy snow and rainfall we have already received.
There is a very high degree of uncertainly in the forecast. Avalanches maybe larger than forecast.Fluctuating freezing levels and rising gale force wind wills create overlapping Avalanche problems
Avoid all avalanche terrain.
As the day progresses rising severe gale Northerly winds will redistribute new snow. This will continue to load on to aspects with previous windslab. Avalanches could be larger than expected Avoid all areas of suspect stiff snowAvoid all avalanche terrain
Storm Slab hazard is likely on all aspects above 1500m. With gale Northerlies developing in the afternoon the storm slab problem will become confined to the southerly 1/2 in wind sheltered areas. Caution on large terrain features, convex rolls and unsupported slopes. The Storm slab is not confined to ridge-crest but distributed more widely through terrain.
it is likely that below 2000m the upper and mid snowpack is isothermic with new snow falling on Wednesday night and Thursday. Rising freezing levels to 2300m on Thursday afternoon will mean a new rain on snow event below 2000m on all aspects.
Loose wet avalanching may also trigger Wet Slabs.Avoid all travel in Avalanche terrain.
0826- observations have been obscured by continuing storm cycle
0824 - Lw avalanching size 1.5 noted across rain affected aspects and elevations. Observations have been limited due to cloud and no operational days due to wind. A large natural avalanche cycle is likely to have occurred
Another 92 mm of rain fell in Mt Cook Village today with a freezing level up to 2400m until it fell sharply from 4:30 pm to below 1800m and is forecast to continue to fall overnight. Winds have mostly been from the East and lite to moderate. Recently developed wind slab is likely buried under new snow. Developing Gale Northerlies in the afternoon will build new Wind slab. The total accumulation of snow at Tasman Saddle during this storm cycle since 0824 could exceed more than 3.5m
There is now a high degree of uncertainty in the snowpack structure.
The snowpack will now need a full re-assessment
Snow, turning to rain with heavy falls below 1700 metres in the afternoon.
Wind at 1000 metres
Easterly 40 km/h, rising to gale northeasterly 65 km/h late morning, and to gale northerly 85 km/h early afternoon.
Wind at 2000 metres
Northeasterly 40 km/h, rising to gale northerly 75 km/h late morning, and to severe gale 120 km/h early afternoon.
Wind at 3000 metres
Northerly 50 km/h, rising to severe gale 90 km/h in the morning, and to severe gale 120 km/h early afternoon.
Freezing level
1700 metres, lowering to 1400 metres before dawn, then lifting to 2300 metres in the afternoon.
Sliding hazard will increase again as gale force Northerlies intensify towards the afternoon. Slick sliding surfaces maybe be buried under recent snow fall.
Low
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
