UPDATED Forecast for Thursday! The storm has arrived earlier than expected, fresh storm slabs reactive to human triggers may form by end of day at treeline and above.
WEDNESDAY NIGHT: Partly cloudy / Light, southwesterly winds / Alpine low -3 C / Freezing level 1500 m.
THURSDAY: Showers and alpine flurries; 5-10 mm. / Moderate, southwesterly winds / Alpine high 2 C / Freezing level 2200 m.
FRIDAY: Rain (snow above roughly 1700 m); 15-25 mm. / Strong, southwesterly winds / Alpine high -1 C / Freezing level 1900 m.
SATURDAY: Mix of sun and cloud / Light, northwesterly winds / Alpine high 0 C / Freezing level 1900 m.
On Tuesday, a natural size 2.5 peristent slab avalanche was reported on a west aspect at 2750 m. Additionally, a skier triggered size 2 storm slab avalanche was reported on an east aspect at 2700 m.
On Monday, a skier remotely triggered a size 2 storm slab from 10 m away on a steep north-facing feature in the alpine; the crown was 20-30 cm deep. A size 2 natural avalanche was observed on a steep east aspect at 2200; the crown was 50 cm deep.
On Sunday, two size 2 storm slab avalanches were triggered by skiers on east aspects at 2200 m. A group of backcountry skiers remote triggered a size 2 storm slab avalanche from 50 m away, failing on a southeast slope at 2250 m. One natural size 2 storm slab avalanche was observed on a steep, north aspect also around 2200-2300 m.
Sun and rising freezing levels are settling the 20-40 cm recent snow on all slopes to 2000 m and sunny slopes in the alpine. Where dry snow remains, pockets of reactive storm snow have developed around ridges and lee features. A total of 50-65 cm snowfall through April now overlies a melt-freeze crust and, in select areas, facets or surface hoar.
Below treeline snow is disappearing rapidly.
Additional snow, wind, and warm temperatures on Thursday may activate recently formed storm slabs at treeline and above..
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Use small slopes without consequence to test the bond of the recent snow.
- Pay attention to changing conditions with elevation/aspect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Expected Size1 - 2
Rising freezing levels and the potential for rain on dry snow may initiate a loose wet avalanche cycle by the end of day.
- A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.
- Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.
Aspects: All aspects.
Elevations: All elevations.