The Safety Refresh — December 2025
Why Wind Matters: Understanding How Wind Impacts Avalanche Conditions
Written by: Ian Fowler, Northern Mountains Backcountry Forecaster
Bob Dylan might not have been thinking about avalanches when he sang “the answer is blowin’ in the wind,” but for anyone traveling in avalanche terrain, that lyric rings true. Wind is one of the most powerful forces shaping the winter snowpack. It doesn’t just move snow around; it changes it by altering both the structure of individual snow crystals and the stability of entire slopes.
That’s why forecasters and backcountry travelers alike pay close attention to wind. Understanding how it transforms snow is key to understanding avalanche conditions.
Wind Transport (Northern San Juan Mountains)
Plumes of snow or flagging on the ridgeline indicate snow is being blown from the left to the right side of the picture. The wind is drifting snow onto all the slopes in this picture.
Photo: Chris Dickson
Understanding Wind Loading Patterns:
Fresh snow forms a beautiful blanket of delicate, white flakes. It is rare for these flakes to remain undisturbed for long before the wind sculpts the snow. Wind-drifted snow is common during or immediately after a storm.
However, wind drifting can continue for days after a snowfall if there's enough loose snow available for transport. Even small changes in wind direction can find new sources of lighter, surface snow to drift.
Wind Scoured Peak (Mt. Epworth)
Textures in the snow give many clues about the wind's effect on the snow. On Mt. Epworth, close to Corona Pass, you can see more textured snow towards the top of the peak, where snow has been scoured by the wind. Over the crest of the peak and into the shade, the snow surface is smooth and almost meringue-like, indicating this is an area where the wind has deposited snow. There is also a small cornice that developed mid-slope due to a sudden change in slope angle. These slopes avalanche almost every year.
Photo: Ian Fowler
Wind accelerates and decelerates as it blows across the terrain, removing and depositing snow in specific ways:
- Scouring: Wind accelerates up windward slopes (facing the wind), removing snow and leaving these areas with shallower or no snow coverage.
- Deposition: Snow is dropped in areas where the wind decelerates.
- Top Loading: When winds decelerate over a ridgeline, snow is deposited on the leeward (downwind) side of the ridge.
- Cross Loading: The process of snow deposition happening on any feature where wind speed slows down, such as gullies, changes in slope angle, or vegetation breaks. These terrain features can be tricky to identify and can happen on slopes that are not directly downwind.
- Slab Formation: Wind jostles pretty little snowflakes, breaking them into smaller fragments. This allows them to pack tightly together and form thick, dense slabs on the leeward side of terrain features. Dense wind slabs often rest on softer snow, which can act as a dangerous weak layer, increasing avalanche risk.
Large Sagging Cornice (Mt. Sopris)
Cornices are sculpted by the wind to create a deadly overhanging mass of snow poised to break off with a small additional load or when the weather warms up. They can break well back from the visible edge and the potential hazard of being under one of these if they release should be obvious. They can also trigger large avalanches on the slope below.
Photo: Brian Lazar
Your Role as a Snow Detective:
In the avalanche forecast, we identify elevations and aspects where you are more likely to trigger Wind Slab avalanches. You also need to conduct your own "detective work" in the field, as small changes in wind direction or terrain features can significantly alter the danger of a slope.
Wind Slab Avalanche (Odessa Gorge)
This Wind Slab avalanche was triggered from the rocks to the left of the person in the photo. This feature faces north. The winds were blowing from the west, over the main ridgeline at the top of the photo. Even though the winds were over the top of the ridge, the westerly winds cross-loaded the slope, building a wind drift along the rocky outcrop.
Photo: Ian Fowler
Look for Clues in the Wind: "The answer is blowin' in the wind," so observe:
- Plumes of snow (flagging) coming off ridgelines to gauge wind direction.
- Look for drifts (tails) of snow behind trees or rocks to indicate the wind direction.
- Weather stations give you a clue about more localized wind direction and speed.
- Wind drifts for smooth, firm pillows that are lens-shaped (thicker in the middle with tapered edges).
- Dappled or scoured areas of softer snow suggest that wind is eroding the snow.
- Cracking in firm surface snow is an obvious sign of unstable, wind-drifted snow.
- Small, safe test slopes can be used to observe how the snow reacts to your weight.
Shooting Cracks in Wind Drifted Snow (Cuchara)
Sometimes you’ll see shooting cracks in firm, drifted snow — a common clue that wind has built a slab. If you spot cracks like this, avoid steep terrain on that aspect and look for a safer route.
Photo: Rich Rogers
Plan your day by highlighting areas you expect to find wind-drifted snow and map out options to avoid these slopes. Once in the field, recognize the clues of wind-drifted snow in low-angle, safer terrain to identify areas where dangerous conditions exist. Modify your plan as needed so you can avoid dangerous slopes in higher-stakes, steeper terrain. As a bonus, riding the soft, dappled snow rather than the chalky firm slabs provides a lot more fun.
Dylan may have been talking about revolution, but for backcountry travelers, Bob is asking you to look where and how the wind is drifting snow to identify dangerous slopes.