In light of significant avalanche activity the forecast has been updated 8:30 March 29, 2018. Caution on shady aspects in the alpine and tree line elevation where a persistent weak layer may be reactive.
Summary
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
THURSDAY: Flurries, accumulation 5-10cm / Moderate to strong southwest wind / Alpine temperature -4 / Freezing level 1300 m. FRIDAY: Cloudy with isolated flurries / Moderate west wind / Alpine temperature -4 / Freezing level 1400m SATURDAY: Cloudy with sunny periods / Light southeast wind / Alpine temperature -2 / Freezing level 1500m
Avalanche Summary
On Tuesday there was a size 1 avalanche that sympathetically triggered a size 3 persistent slab avalanche resulting in a burial. This was on a northeast aspect at 2000m, 50cm deep. Additionally there were reports of natural persistent slab avalanches size 2.5-3 on southeast through northeast aspects between 1800 and 2000m. Additionally reports on Monday show explosives and skier controlled triggered storm and wind slab avalanches to size 1.5 on north and east aspects in the alpine. On Sunday there was a report of a skier-triggered cornice failure (size 2) on a northwest aspect at 2100 m, as well as skier and sledder triggered storm slabs (size 1.5) on east and north aspects in the alpine. Explosive control work also produced cornice failures, size 2-3 with little effect on the slopes below.
Snowpack Summary
Another 5-10 cm of storm snow with strong southerly wind Sunday night adds to last week's storm which delivered 20 to 50 cm of snow accompanied by strong to extreme wind out of the southwest, south and southeast. This storm snow rests on the March 21st interface, a mix of moist grains at low elevations, crusts on solar aspects at all elevations and surface hoar/facets on north/east facing features at treeline and alpine elevations. Some west facing features may have surface hoar on top of a crust. This layer has shown to be reactive.Deeper in the snowpack, 80 to 140 cm below the surface is a combination of facets, surface hoar, and/or crust known as the mid-February layer. This interface has not been active recently.The mid and lower snowpack are strong and well settled.
mbender,
Avalanche Canada
