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Avalanche Forecast

Archived

Feb 20th, 2023–Feb 21st, 2023

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

North Island.

Overnight snowfall and wind will form fresh storm slabs that will be deepest and most reactive in wind-loaded terrain. Avoid avalanche terrain in the alpine and seek out sheltered, lower-angled slopes with no overhead hazard for the best and safest riding.

Confidence

Low

Avalanche Summary

No new avalanches have been reported in the past few days, but observations are very limited in this area. We suspect natural and human-triggered wind slabs will be likely in the alpine and treeline on Tuesday if the forecasted 20-30 cm of new snow arrives on Monday night.

Snowpack Summary

A crust near or on the surface exists at lower elevations from warm temperatures and rain on Monday. At higher elevations, 20-40 cm of recent snowfall has been redistributed by northwesterly winds, scouring windward slopes and depositing wind slabs in lee areas. A crust can be found down 20-70 cm that extends to mountain tops on all aspects. Recent reports suggest this crust is bonding poorly to the snow above.

The remainder of the snowpack is consolidated and strong.

Weather Summary

Monday night

Cloudy with flurries, 15 to 25 cm of accumulation. Alpine temperatures drop to a low of -6 °C. Ridge wind northwest 50 km/h gusting to 80 km/h. Freezing level 500 metres.

Tuesday

Cloudy with flurries, 5-15 cm of accumulation. Alpine temperatures drop to -10 °C. Ridge wind northwest 50 km/h easing to 30 km/h in the afternoon. Freezing level dropping to valley bottom.

Wednesday

Cloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -9 °C. Ridge wind northeast 10-20 km/h. Freezing level 300 metres.

Thursday

A mix of sun and cloud. Alpine temperatures reach a high of -10 °C. Ridge wind east 5-15 km/h. Freezing level at valley bottom.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Dial back your terrain choices if you are seeing more than 20 cm of new snow.
  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Wind slabs may be poorly bonded to the underlying crust.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.