Avalanche Forecast
Issued: Jan 2nd, 2020 5:00PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSnowfall through Thursday night and Friday combined with wind and warm temperatures will keep the avalanche danger at High on Friday.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
Thursday Night: Snow, accumulation 10-20 cm . Alpine temperature -10 C. Moderate northwest wind.
Friday: Snow, accumulation 10-15 cm. Alpine temperature -5 C. Moderate to strong west wind. Freezing level 1400 m.
Saturday: Snow, accumulation 10-15 cm. Alpine temperature -6 C. Moderate to strong southwest wind. Freezing level 1200 m.
Sunday: Flurries. Alpine temperature -6 C. Moderate southwest wind. Freezing level 1000m.
Avalanche Summary
There was a widespread natural storm slab avalanche cycle to size 2.5 on Wednesday. Avalanches were 30-60 cm deep and were reported on all aspects and elevations. Additionally there were several human triggered avalanches reported up to size 2. Some of these were remotely (from a distance) triggered.
Snowpack Summary
Expect another 10-20 cm of new snow overnight Thursday to add to the 40-70 cm that fell through the New Year's period. All this recent snow has buried a layer of surface hoar found at all elevations. In some places the surface hoar may be combined with sun crust on steep sun-exposed aspects.
A weak layer that was buried at the end of December is now approximately 100 cm deep and may present as surface hoar in sheltered areas, sun crust on steep solar aspects and/or a melt freeze crust below 1700 m.
An additional layer of surface hoar buried mid December is 110-180 cm deep. Avalanche activity on this layer has tapered off, but there is still concern for heavy loads to step down to this layer. A crust from late November is now over 180 cm deep. Concern for this layer is limited to rocky or variable snowpack depth areas in the alpine where it most likely exists as a combination of facets and crust.
Terrain and Travel
- Minimize exposure during periods of heavy loading from new snow and wind.
- Avoid freshly wind loaded terrain features.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Storm slab size and sensitivity to triggering will likely increase through the day.
Problems
Storm Slabs
Snowfall continues to accumulate above a recently buried layer of weak surface hoar. Expect storm slabs to remain reactive as the load builds and temperatures rise.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
There is still concern for heavy loads (storm slab avalanches running) to step down and trigger deeper weak layers buried in December.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 3rd, 2020 5:00PM