Up to around 70cm snow has fallen over the last 2 or so days. Expect widespread windslab to have developed at the high and middle elevation bands, and expect loose snow avalanche potential where the wind hasn't packed the snow.
Saturday will be fine weather but also hazardous, with natural avalanching still possible when the sun hits the slopes. Watch out for what is above you in the steep sided Fiordland valleys.
Be very cautious on Saturday, stick to flattish places if you are unsure.
Please submit any observations you make. They are most appreciated.
Windslab developed over Thursday and Friday. Expect it in the top elevation steeper lee slopes just off the ridgelines. Some natural avalanches are expected.
At the mid elevations expect the slab over a rain crust below about 1600m.
Loose dry avalanching could be expected in areas where the wind hasn't pressed the snow into a slab. Below about 1600m the new snow is on top of a rain crust and travel could be tricky
Fri 31st- no activity reported but some expected.
Thur 30th July- some natural activity reported in the Homer area over the day. Slab to sz 2.
Please see the public observations for some photos from the Darran's on Sunday. Cold dry snow, very wind affected. Some cliff band activity observed. Isolated cracking seen when skinning on wind loaded areas in Homer area.
Observations from Milford Track area, Darran's and Routeburn on 20 July -Slick frozen conditions below 17/1800m. Only the highest peaks (North Peak, Talbot, Mt Christina) had some slopes with enough snow to cover terrain features and look wind loaded.
Fri 31st- The storm total is around130mm of precip, which should equate to around 70cm of snow above around 1600m and less below where there has been a mix or snow and rain.
Fri 31st- Around 30cm snow fell over the day. Snow was initially down to 1400m but later in the day down to 400m. Expect continued slab development lee to initially the west and then the south. The snow below around 1400m is expected to be lying over a rain crust.
Thur 30th July- in northern Fiordland about 30cm fell from the NW over the day, with snow initially down to about 1700m and then down to about 1100m.
Wed 29th July- In northern Fiordland around 10cm fell over Wednesday, down to around 1850m.
Mon 27th July-Currently the snowpack is starting to become more stable, as temperatures rise after 3 days of very cold temps. In Northern Fiordland an estimated 50cm cm fell from the South to SW above about 1700m between Wed 22nd and Fri 24th July, with rain below this for most of the storm. Temperatures dropped at the end of the storm and snow fell to 600m.
Prior to July 24th the snowpack was very shallow, with most slopes below 1700m being below threshold (not enough snow to avalanche). Only slopes at the highest elevations had a layered pack.
Mon 21st July - Below around 1800m the thin snowpack had a mixture of rain and snow over the week of 13th to 18th July, culminating in rain up to about 1750m on Saturday the 18th. This snowpack is generally thin, with much of it still below avalanche threshold, and rainsoaked and refrozen. Above about 1800m there has been about 80 or 90 cm fall in northern Fiordland and about 60cm in the south, from a series of westerly fronts over the week of 13th to 18th July. There were warm temperatures on Saturday 18th and this snowpack is now thought to be stable, with possible remaining wind slab at the high elevation areas lee to the west but should be treated cautiously as there have been not observers in the field.
Continues snow to around midnight Friday. Clearing Saturday.
Surface conditions are variable, with wind scouring on windward slopes. Take an axe and crampons if you're exploring.
Moderate
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
