Arthur's Pass

Increasing wind slab avalanche hazard forming tomorrow from westerly winds and precipitation. Caution of the changing hazard for any backcountry travel tomorrow. Look for wind transport and if there is more than 10cm of new snow expect elevated avalanche hazard.

A natural avalanche cycle is expected to have occurred during the storm during the week.

Park user observations provide important information. Please help us.

If you see anything, please report it in the public observations section of the NZAA website.

500+ mm of rain has fallen in western areas of the Park in the last week; part of this was snow to Arthurs Pass Village on Thursday, which melted when the rain returned. This has been accompanied by fluctuating freezing levels. Most areas below ~2100m will have received a snow-rain-snow combination, followed by snow falling to ~900m on Thursday. Snow totals remain to be determined once the storm concludes but the threshold for avalanches in western areas of the Park close to the divide is probably around 1500m, tapering to the east. A series of rain on snow events over the past weeks mean rain percolation channels will be well established in the snowpack below ~1800m and new channels will be forming to the highest elevations during this storm's heavy rain precipitation. Strong to gale winds from the northerly half will have formed windslabs on south- through east-facing slopes and around terrain features. The underlying snowpack was well consolidated prior to the storm and once drained is unlikely to hold deeper layers of concern for avalanche hazard.

Showers, some heavy, with snow to 800 metres, easing in the evening. Winds Westerly 50 km/h. Freezing level 1000 lowering to 600 metres evening.

Temple Basin forecast to get 17cm tomorrow.

Conditions are changing. Slick surfaces currently exist below 2200m; crampons and an ice axe are recommended.

Moderate

• We are uncertain about forecast precipitation amounts.
• We are uncertain about forecast snowfall amounts.