Regions
Northwest Inland.
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Tuesday
Weather Forecast
Synopsis: The ridge of high pressure will continue dominate the weather through Tuesday before breaking down as frontal system makes landfall Wednesday.Tuesday: Freezing Level: 500 - 1200m Precipitation: Nil; Wind: Treeline: Light, SW | Ridgetop: Moderate, NWWednesday: Freezing Level: 400m - 1100m; Precipitation: 2:7mm - 2:12cm; Wind: Treeline: Light, SW increasing to moderate SE | Ridgetop: Strong, SWThursday: Freezing Level: Valley Bottom 700m; Precipitation: 2:3mm - 2:6cm; Wind: Treeline: Strong, S | Ridgetop: Strong:Extreme, SW
Avalanche Summary
No new activity to report from Sunday.In the neighboring NW Coastal region, Avalanche activity on Sunday was limited to point releases from steep terrain.
Snowpack Summary
It's starting to feel like spring in the NW. Valley temps are creeping into the double digits during the day, and there are reports of the top 15 cm of the snowpack becoming moist during daytime heating.The last significant shot of snow was on March 27th, 10 - 15 fell on March 30th. This new snow rests on top of a haggard old surface composed of old wind slab, melt freeze crust, and faceted old snow. Ongoing melt freeze cycles will likely help to heal any surface instabilities.The early March layer found in the upper snowpack is composed of facets/surface hoar on shady aspects and facets/crust on southerly aspects. I suspect this layer has been the culprit in the human triggered avalanches from March 27/28 in the neighboring NW Coastal region, that are being reported on the Balktalk Facebook Page.The early February crust/facet/surface hoar combo can be found deep in the snowpack, although I suspect it's gone dormant for now.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.