Central Sierra Nevada

Triggering an avalanche is unlikely today on a regional scale. Very isolated areas of instability are not impossible today from wind drifted snow (wind slabs) or unexpected lingering deep persistent slab instability.  Travel using normal caution tactics with a plan to step back into safer terrain if conditions present as different than expected. LOW avalanche danger exists for all elevations.

Normal caution

Fifteen backcountry avalanche fatalities occurred this past week in the United States including one in California. We express our condolences to the friends and family of the deceased. It is my hope that each of us seek to learn from these accidents rather than pick them apart to highlight others' mistakes or write them off as unlucky or circumstances beyond control. I suspect each of these individuals intentionally chose to travel in or below avalanche terrain and none of them thought they were making a wrong decision, just like you and me.

The snowpack has continued to gain strength since the last series of storms. The likelihood of triggering an avalanche is in the unlikely category on a regional scale. This is different than impossible as isolated instability may still exist on the slope scale.  Travel using the techniques of normal caution to minimize the consequences of an unexpected avalanche event.

Winds slabs:  Wind slabs that formed this past Sunday-Thursday on all aspects near and above treeline have had a chance to bond and gain strength over the past two days. Increasing SW winds today are not expected to drift much snow due to previous stronger winds and melt-freeze crust now on the surface of windward aspects. A small unstable wind slab is not out of the question today, but would likely be size D1. Give a little extra space around recently formed cornices and wind pillows, especially if you see any blowing snow.

Deep Persistent Slabs: Six days have passed since the last known deep slab avalanche occurred on Feb 2. In this time the old weak layers in the snowpack on NW-N-NE aspects that were heavily loaded by the Jan 26-29 storm cycle have had time to adjust to the new load and gain strength under a deeper snowpack. It appears that this deep slab avalanche cycle has come to an end. That said, deep slabs are less predictable at the tail end of the cycle so do not let your guard down with lackadaisical travel techniques. Think "If this slope avalanches, it could be big" and travel accordingly especially in terms of selecting spots to regroup before or after passing through or below avalanche terrain.

Recent Observations:

* Signs of old wind slab and old deep persistent slab avalanches from Jan 26 through Feb 4 are visible in many locations around the forecast area.

* A patchwork of wind slab and wind scoured areas exists in near treeline and above treeline terrain on all aspects.

* Snow surface melt and overnight crust formation has occurred in the vast majority of sun exposed areas. Only well shaded slopes at mid and upper elevations have escaped snow surface melt.

* Snowpit data has shown strength gains at all heights in the snowpack. The recent storm snow that makes up the top half to two-thirds of the snowpack has bonded well. Old deeper weak layers in the lower portion of the snowpack have significantly reduced reactivity or signs of instability in snowpit tests. These deeper layers do not gain strength at the same rate in all locations so there will continue to be isolated unstable test results that should not be ignored and could be some of the only clues to isolated lingering deep instability.