Silver Valley & Bitterroot Mountains

Be mindful of shallow, dense slabs of snow that have formed on top of weaker snow layers and a firm crust at upper elevations that could produce small avalanches below ridgelines and in steep gullies. The absence of freezing temperatures overnight, and daytime highs well into the 40's, will increase the likelihood of wet snow problems today. Limit your exposure time in more complex terrain and run-out zones, and continue to use safe travel protocol in the mountains.

Snowfall from the last week fell on very worrisome weak layers, most notably a layer of large, buried surface hoar that has been found on all aspects above about 5500 feet. This weak layer was initially buried by light snowfall on January 28th, and in many locations, strong southwest winds and settling have helped strengthen the overlying slab over the past few days, however variability of the volume of snow and slab thickness, favoring our Nothern zones, means the distribution of the problem is not uniform.

In the Silver Valley and Bitterroot Mountains, the danger remains Low. In part due to higher freezing levels, but mostly due to significantly less snowfall within the past week (Bitterroot Mountains Observation). Up north, the buried surface hoar appears to be almost everywhere above the recent rain/snow lines persistent weak layers and it is now buried up to a foot below the surface in favored locations. Recent observations have uncovered very large feathers, intact and upright, having survived even in areas atypical like open slopes on the windward side of ridgelines, or directly on the ridgetops (Selkirks Observation). Surface hoar is a weak layer that is not to be underestimated. Many avalanche professionals and recreationists alike have been involved in near-misses or accidents, where a layer of buried surface hoar collapsed and propagated an avalanche wider than expected or in a place where it was not known to exist. The signs of instability are not always there, and the potential consequence of a surprise can be severe.

With the lack of overnight refreeze, todays temperatures forecast to reach well into the 40's and sun at above the valley inversions, wet snow problems could become more likely this afternoon.  Boot penetration that exceeds your boot cuffs is as sign that the snow has lost, or is loosing, cohesion and wet loose problems are increasingly likely.

With the elevated temperatures today, the best skiing and riding conditions will likely be found on non-solar north through east slopes, the same locations you are most likely to encounter the thickest, most reactive and most dangerous slabs. Be heads up today for tell-tale signs of instability such as whoomphs and cracking that extends in front of your skies, although propagation under these conditions can occur without warning. The easiest way to manage the avalanche hazard today is terrain management and slope angle.

---

IPAC is now on the Avy app! View, submit, and share observations on the go using the AvyApp. Your backcountry observations are critical for building our avalanche forecasts. Avy provides a centralized location for core trip planning, and you can view streamlined, up-to-date avalanche and weather forecasts for your selected zone, using offline caching. Download Avy today - App Store and Google Play.