Keep a close eye on how the temperature and sun are affecting the snowpack in your local zone. The freezing level is forecasted to rise well into the alpine for Tuesday morning, but other factors may keep the upper snowpack cool, lowering avalanche danger.
Cornices may become weak with rising temperatures. Cornice falls are hazardous on their own, and have the potential to trigger large avalanches on the slope below.
With freezing levels rising into the alpine, the surface snow may become moist or wet, and natural and rider triggered loose wet avalanches could become likely.
The size of these avalanches will be mostly influenced by how deep the loose snow is.
Pay close attention to conditions as they change through the day, the conditions you experience could be anywhere between the two extremes mentioned above.
MONDAY NIGHT: Clear. No new snow/rain expected. Light north ridgetop wind. Freezing levels around 2000 m.
TUESDAY: Mostly clear in the morning, increasing cloud through the day. Light variable ridgetop winds. Freezing levels approach 2500 m.
WEDNESDAY: Partly cloudy. Light to moderate snowfall expected with rain at low elevations. Light to moderate southwest ridgetop wind. Freezing level falls to around 1400 m.
THURSDAY: Partly cloudy. Very light snow/rain expected. Light variable ridgetop wind. Freezing level falling to around 750 m overnight, back up to 1500 m through the day.
On Monday in the Whistler area, explosive avalanche control produced cornice avalanches up to size 2.5, and a few small storm slab avalanches in the alpine. Small loose wet avalanche activity continued with warming and rider traffic.
On Saturday and Sunday, small loose wet avalanches were naturally triggered by warm temperatures and short periods of sunshine.
On Saturday, at higher elevations, new storm slabs were reactive to human triggers to size 1.
A large avalanche was reported on a steep alpine slope near Blackcomb on Thursday, likely failing on the mid February weak layer, now buried around 80 cm deep. While the trigger is unknown, it's likely that warming and strong sun had weakened the snowpack.
With freezing levels rising to 2500 m, moist snow is expected on all aspects into the alpine. On the highest peaks, Above 2500 m, storm slabs sit on wind affected surfaces in shaded alpine areas, and on a sun crust on south facing slopes. Storm accumulations near Whistler range from 15-30 cm, with higher accumulations north of the Jervis Inlet.
40 to 100 cm overlies the mid March interfaces. This layer exists as surface hoar in shady, wind-sheltered areas and a hard crust on sun-exposed slopes into the alpine. Several other weak layers exist in the upper and mid snowpack, reports suggest these layers are bonding well and avalanche activity is unlikely except from large loads like cornice falls.
