The storm rolls on! Ongoing NW winds and a top up of snow will keep the wind slab hazard at considerable, especially near the Divide.
We are now into the fifth day of this storm with limited observations and very little data from the Divide. It's hard to know exactly what's happening, so maintain a conservative approach.
Up to 5cm in the south of the forecast area and 10-15cm near the Divide with continuing gale northwesterlies will keep the windslab hazard at considerable, especially near the Divide.
Avoid steep, recently loaded slopes.
Heavy rain below around 1200m about the Divide and freezing levels rising to 2200m elsewhere will continue to produce loose wet avalanches.
Watch out for wet sticky snow or rollerballing, as these are clear signs the snowpack is losing strength.
We still have limited field observations due to the ongoing storm. It looks like roughly 25cm of new snow has fallen in the south of the forecast area since the storm started on Friday, with an estimated 40-50cm near the Divide. Gale and severe gale northwesterly winds have stripped exposed areas back to a hard crust and loaded sheltered terrain.
This sit on a well settled lower snowpack, with slick crusts on solar aspects and shady slopes below 2000m. Faceting has been observed in the lower pack, but after warm temperatures and lots of sun this should be limited to shady slopes above 2000m. We will be monitoring these layers as the storm brings additional load through the start of the week.
Heavy rain developing about the divide in the morning, with snow to 1200 metres, cloudy elsewhere.
Wind at 1000 metres: Northwesterly severe gale 90 km/h, rising to severe gale 120 km/h for a time in the morning.
Wind at 2000 metres: Severe gale 120 km/h south of Lake Coleridge in the morning and early afternoon.
Freezing level: 1500 metres about the divide in the morning, otherwise 2200 metres.
Observations remain limited by bad weather. Ohau Ski Patrol reported a natural wind slab avalanche cycle on August 23rd in sheltered terrain near ridgeline, with several size 1 avalanches and one size 2 avalanche on northeast through to south facing slopes.
Gale northwesterly winds have scoured exposed areas back to slick crusts. Take an ice axe and crampons for travel at higher elevations.
Low
New Zealand Avalanche Advisory (NZ Mountain Safety Council)
