Storm Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1–2
A storm slab avalanche problem is expected to develop from north to south through the forecast area as the day progresses. The likelihood of backcountry travelers triggering an avalanche is expected to steadily increase through the morning and afternoon hours, followed by a substantial and rapid increase in instability expected during the last few hours of the day prior to sunset. A natural avalanche cycle may occur during the period of peak instability, which is expected between 5 pm and midnight.
This projected timing is dependent on the weather forecast, which we all know does not always verify with complete accuracy. Pay close attention to changing conditions today, anticipating that a shift from stable to unstable conditions may occur in less than a 1 hour period and may not align with the above projected timeline depending on how the storm verifies.
Unstable slabs are expected to form first in wind loaded areas. The winds are gale force today out of the SW, so blowing and drifting snow is expected to be widespread. Snow surface cracking in areas along the downwind side of ridgetops and other terrain features is likely today's first clue to the presence of unstable snow. With the expected rapid increase in snowfall rates and new snow accumulation later today, unstable slabs are expected to spread rapidly from wind loaded areas to wind sheltered terrain, including below treeline areas. Potential avalanche size is expected to increase from small to large as the day progresses.
Pay attention to the depth of new snow in the areas you are traveling and look for signs of instability repeatedly during your outing. Go out of your way to periodically move into untracked snow and/or onto small test slope terrain features to look for snow surface cracking. When you start to encounter snow surface cracking or slab failures on small test slopes, it is time to pull back from avalanche terrain and opt for safer route options. Remember that the switch from stable to unstable conditions may occur over a very short period of time today.
Expect unstable slabs to form first today in wind loaded areas, then spread to wind protected terrain. A skier triggered avalanche that occurred in wind loaded terrain above Crater Lake, Carson Pass area, March 6, 2025.