Solar input is the main issue in the Yoho region, as the lower snowpack is stronger here than further east in the Rockies. Friday's danger ratings reflect daytime heating, then the clouds roll in late in the day and the snow surface should remain mostly cool into the weekend.
Strong solar inputs could produce avalanches in steep rocky solar terrain. Pinwheeling and melting snow near rock are good indicators that the snowpack is being affected by solar radiation.
Continue to pay attention to the weaker basal facet layer in areas where the snowpack is shallower (<2 m) such as moraines or wind scoured areas, or in places where a large trigger like a cornice fall could impact the slope. In deeper snowpack areas of this region the basal facets are less of a concern.
The ridge of high pressure that has dominated the weather pattern this week is breaking down overnight and we can expect a change starting Friday. The weather switches to a SW flow, the wind will increase to 40 km/hr and a few flurries are expected and we might get 5 cm by Saturday. Freezing levels are forecasted to be about the same: 1500-2000 m.
No new avalanches were reported in the Yoho area today, but our field team observed a 1-2 day old size 2.5 deep persistent slab on Dolomite peak today. Ski hills reported a warm day, but the snow surface remained mostly cool except on steep solar aspects. But, currently, its 4 pm and the sun is high for a few more hours...
Surface crusts exist to ridgetop on solar aspects. On polar aspects, 10-25cm of storm snow sits over a facetted interface from March 25th and buried temperature crusts below 1500 m. The midpack in this area is generally strong, although the base of the snowpack consists of weaker facets in thinner areas (<2 m).
