Since yesterday morning, average wind speeds at 10,000 feet were in the twenties with gusts into the thirties and forties. These winds have transported snow at the upper elevations onto leeward slopes and formed wind slabs. Yesterday in GTNP, a small wind slab avalanche released naturally and ran a few thousand feet. Similar events could occur today and it will be possible for skiers and riders to trigger small slab avalanches above 9,000 feet. Below 9,000 feet, avalanche activity will be limited to small pockets and isolated to steep terrain. The likelihood of triggering an avalanche will increase on sheltered solar aspects during the warmest portion of the day. Although these slides will be small, in serious terrain consequences could be high.
Steady winds have formed wind slabs at the upper elevations. These avalanches are expected to be small soft slabs less than a foot in depth. Below the new snow are firm crusts, which could cause these avalanches to entrain snow and run long distances. To avoid encountering a wind slab avalanche, backcountry travelers should be wary of wind-loaded slopes and terrain features at all elevations.
A quick moving system will bring pacific moisture to the region Sunday morning. By the end of tomorrow, there could be 4 to 8 inches of accumulation in the mountains and a few inches in the valleys. Temperatures at 10,000 feet will be in the low twenties and valleys will warm to the freezing level. Southwesterly to westerly ridgetop winds will continue to be the upper teens with gusts into the twenties. Recent wind and snow have formed wind slabs above 9,000 feet, and additional loading from tomorrow’s snowfall will continue to build these slabs. Skiers and riders could trigger small soft slab avalanches, up to a foot in depth, at the upper elevations on steep leeward slopes. Due to the underlying crusts, these small avalanches could entrain snow and run longer distances on steep sustained slopes. Below 9,000 feet, avalanche activity will be unlikely and isolated to small pockets on steep terrain.
