Presidential Range

Triggering an avalanche is unlikely, but LOW avalanche danger does not mean no avalanche danger. Continue to be wary of hard wind drifts and slabs in steep terrain - many rest on top of weak, sugary snow.  Also watch for small, thin drifts that could knock you off your feet in steep terrain.

You are most likely to find trouble on slopes around 35 degrees or steeper. As always, think about where even a small avalanche could carry you before committing to consequential, previously wind-loaded slopes.New Wind Slabs: New, thin wind slabs may have formed in easterly terrain yesterday from moderate northwest winds and 1.2 inches of low density (5%) snow. Forecasters in the field yesterday saw scouring in many places but some areas of new snow blanketed terrain. Although unconsolidated in many places, there is the potential that several hours of continued wind into yesterday afternoon formed small, thin slabs in isolated locations. These wind slabs will be easily identifiable as smooth, bright white areas of softer, drifted snow and cracking under your feet.

The primary concern with these newer wind slabs is the potential for causing a fall in steep terrain. These slabs are expected to be small and isolated, so they don’t rise to an avalanche “problem” today, but in very steep terrain even a shallow slab can knock you off your feet with serious consequences. Look for new slabs on northeast through south aspects above 4,000 ft. If you encounter drifted snow, assess the new/old snow interface using hand shears.

Photo: Mount Washington Avalanche Center

Old Hard Wind Slabs: Lingering hard slabs in steep terrain are mostly wind-hardened and generally unreactive to the weight of a skier. That said, continue to pay attention in very steep, consequential terrain where hard slabs may sit over weak, sugary faceted snow - a structure that can feel or sound hollow or “drummy,” especially in steep gullies. Although unlikely, it is still possible to trigger one of these old hard slabs from a thin spot in the snowpack, most commonly near rocks (buried or exposed), along slab edges, or on convexities and unsupported slopes where the slab thins to less than 2 feet thick. Manage this by visually assessing hard, wind-hardened snow surfaces and digging down to check the slab/weak-layer interface if you encounter hollow-sounding snow.Outlook: A weak storm system develops off the Mid-Atlantic coast tonight and tracks eastward offshore. While the main low stays out to sea, a trailing disturbance and cold front move through New England. Because the system is relatively moisture-limited, snowfall totals should be modest at 3-5 inches. 

NWS guidance suggests very low-density snowfall (around 5%), meaning the new snow will be light, dry, and easy to move. As snow develops tonight into Saturday, light northwest winds during the first half of the day around 20 mph will be sufficient to begin transporting new snow in exposed terrain above treeline. Later Saturday, as winds increase into the 35–50 mph range, transport will become much more efficient. Expect upper-elevation windward slopes and ridgelines to be scoured while lee terrain accumulates snow quickly. This will preferentially load easterly aspects especially below ridgelines, in gullies, and on convexities where drifts build. The result is an increased likelihood of fresh wind slabs forming, and avalanche danger can rise faster than snowfall totals alone would suggest due to concentrated wind loading in specific start zones.

Expect avalanche danger to rise during the day tomorrow.  

OBSERVATIONS: Please consider submitting an observation on our website or in the new Avy phone app of what you are seeing in your travels. Submitting an observation hones your skills, informs other users, and improves our forecasts.