Strong winds and overnight snow will promote storm slab formation Monday morning.
Natural avalanche activity is likely Sunday night through Monday.
Incoming snow with strong SW winds will rapidly build reactive storm slabs in Alpine and Treeline lee features. The peak of the system will hit in the middle of the night, but expect sensitive surface slabs Monday morning.
Several sz 2-3 natural avalanches were reported from the backcountry Saturday.
Cheops North 4 had a loose avalanche step down to the storm slab interface lower in the path.
A sz 2.5 cornice failure off Mt Bonney scrubbed the face below down to glacier ice.
This past week's 60cm of storm snow and strong SW winds have formed several potential failure planes in the upper snowpack, especially in wind exposed areas.
The mid-snowpack consists of generally well bonded, rounded grains.
The Nov 17 deep persistent weak layer, composed of large facets and in some locations a decomposing crust, has been dormant in GNP for several weeks now.
A vigorous frontal system plows through Rogers Pass Sunday night, bringing strong winds, snow, and mild temps.
Tonight: snow, 20cm, Alp low -8*C, mod/gusting strong SW winds, 800m FZL
Mon: convective flurries, trace to 5cm, Alp high -8*C, light/gusting moderate W winds, 1000m FZL
Tues: mix of sun/cloud, Alp high -10*C, light NW winds
