The complex and intense storm continues with heavy snowfall and forecast gale winds.
There is a very high degree of uncertainly at present, avalanches maybe larger than forecast and could run to valley floor.
Fluctuating freezing levels and forecast gale force winds will have created overlapping Avalanche problems
Avoid all avalanche terrain.
There is a large amount of snow available for transport - visibility is limited. Forecast severe gale Northerly winds will create areas of touchy stiff wind slab that may extend well below ridgecrestAvoid all areas of suspect stiff snowAvoid all avalanche terrain
If the forecast rising freezing levels do not reach elevations predicted, Storm Slab may continue to persist on nearly all aspects where terrain provides shelter from forecast winds.Poor visibility will make it hard to identify avalanche terrain, convex rolls, unsupported slopes and terrain traps.
Storm slab will exist through out the terrain and will not be confined to ridge-crest start zones.Avoid all avalanche terrain
Rising freezing levels on Thursday night will have produced a new round of Loose Wet avalanching. With considerable amounts of new snow down to low elevations, rain on snow is very likely to produce further Loose wet avalanching on lower than expected slope angles.
Loose wet avalanching may also trigger Wet Slabs.Avoid all travel in Avalanche terrain and be very mindful of terrain above you if you are traveling close to the divide or under large terrain features in valley floors.
27th August - Haszard range - some observations of Loose wet avalanching during the afternoon on various aspects at 2000m and below. A brief break in the weather allowed for observations of Wet slab avalanches on East Aspects around 1100m. Poor visibility hindered any other observations
26th August - Large Loose wet avalanche reported running to valley floor on Mt Ollivier Fan below Mueller Ridgeline reaching the lower bush line. Further observations restricted by current storm cycle.
24th August - Haszard Range - Skier Accidental Wind Slab size 1.5 at 2000m Easterly Aspect on 33 degree slope running on a buried 1mm Facet layer. 1 person caught in debris but remained on surface. Loose Wet avalanching size 1.5 noted across rain affected aspects and elevations observed from Mt Cook village.
Mueller Hut has recorded around 50cm of new snow to 6pm on Thursday evening. Snow was falling to ground level in Mt Cook village for the majority of the day. After 4pm the freezing level rose to around 1400m. This is added to the 92 mm of rain fell in Mt Cook Village on Wednesday with a freezing level up to 2400m. Winds have mostly been variable and do not appear to be as strong as forecast.
The snowpack is now likely to be highly complex with fluctuating freezing levels and uncertain wind strengths
The total accumulation of snow at Tasman Saddle during this storm cycle since 24th of August is now likely to exceed more than 5m
The snowpack will now need a full re-assessment when the weather allow
Heavy rain, with snow lowering to 1200 metres for a time in the morning, easing to showers in the afternoon.
Wind at 1000 metres
Gale northwesterly 70 km/h, easing to 50 km/h in the evening.
Wind at 2000 metres
Northerly severe gale 110 km/h, easing to gale 70 km/h in the morning, turning westerly 60 km/h early evening.
Wind at 3000 metres
Severe gale northwesterly 110 km/h, changing gale westerly 85 km/h in the afternoon.
Freezing level
2100 metres, lowering to 1800 metres before dawn, and to 1400 metres in the evening.
Forecast Gale force Northerlies will strip exposed ridgelines. Ice axe and crampons advised if you must travel
Low
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
