Boletín de aludes

Although becoming less likely, triggering a 3' deep persistent slab avalanche remains possible. You're most likely to find this problem on steep, rocky slopes where the slab is thinnest. You may not observe any obvious signs of instability before triggering a persistent slab. The weight of a snowmachine is more likely to impact deeply buried weak layers than the weight of a person.

For nearly three straight weeks in January, high pressure persisted across the region. During this time, weak snow (facets and surface hoar) and crusts formed at or near the snow surface. These layers were buried on January 31st as a mulit-day atmospheric river brought 4-5 feet of snow (7-8"SWE) from January 31st-February 5th. Some light snow showers continued from February 7-9, bringing some low-density snow atop the recent storm snow. Instability peak sometime Sunday-Tuesday (2nd-4th), with widespread natural and human-triggered avalanche activity. Many observers reported remote triggering across the forecast zone. Since the peak, avalanche activity and obvious signs of instability have decreased substantially. A very dense slab 3-4 feet thick is overlying the weak snow that formed during the January drought. The good and bad news is how deep these persistent weak layers are buried. Good, because it's becoming difficult to trigger and these weak layers are beginning to strengthen. Bad, because if you trigger a persistent slab, it's likely to be 3' deep and you may not see any obvious signs of instability. It's relatively easy to stay out of harm's way when the snowpack is screaming at you (peak instability). It's much more difficult to be patient after the storm passes and the in-your-face signs are absent. I am most suspect of steep, rocky terrain that did not already avalanche. 

A storm system will be impacting the West Central mountains today through Friday. The bulk of the precipitation looks to be to our south. 6-10" with E/SE winds are forecasted for our region. Southern areas, including West Mountain could receive the higher end totals. I don't expect this storm to change the avalanche conditions much during the day Thursday. Overnight and into Friday morning, you could find soft slabs of new storm snow 6-12+" thick. If the storm arrives earlier than anticipated, expect an uptick in avalanche danger before the days end.

Thanks to all those folks who submitted observations during last week's cycle. We received some great information over the past 10 days. Submitting observations helps improve our avalanche forecasts.