It has been almost a week now since we have heard of, or seen, any ‘slab’ avalanche activity. There has been a handful of wet loose snow avalanches mainly associated with the 2-3″ of snow from Friday. Yet, the snowfall (and related sluffing) was relegated to areas close to Turnagain Arm and Portage Valley. The snowpack continues to show signs of handling the spring-time warm conditions with good stability.
For today, and the early part of this week, our main snowpack concerns continue to be wet loose avalanches and cornice falls. Although the wind will pick up from the East, there is little to no snow available for transport and the wind will likely be just an inconvenience.
Wet Loose Avalanches:
It will be possible to trigger wet sluffs in very steep terrain with surface warming – slopes over 40 degrees, either in the lower elevations or on sunlit aspects in the higher elevations. The volume of any potential sluff will likely be low and slow moving.
Cornices:
We have yet to see any significant cornice falls in the area. Despite this, it is still worth being aware of and staying away from them. Know where you are in relation to cornices and always hedge your bets by giving them a wide berth. Warm temperatures and sunshine will help to destabilize cornices.
Overnight Ridgetop Temperatures:
Last night was the warmest night we have seen this spring. Ridgetop temperatures remained at, or very near, 32deg (they have been dropping to the mid 20’sF until now). These warm overnight temperatures are something avalanche practitioners pay close attention to in the spring. After 3 consecutive nights where ridgetops are above freezing, the snowpack can begin to melt-down, or shed. In this case large and destructive wet avalanches, which can run to valley bottoms, become a real concern. Our snowpack this spring has undergone so much melt and freeze (remember January?) that how it will react to future warm nights is uncertain. We may simply see the pack melt out with minor wet avalanche activity, which is likely the case, but not something to bet on AT ALL as we enter into the warmer days of late April and May. Keeping an eye on the upper elevation temperature trends, cloud cover and any overnight re-freeze of the surface will be good things to watch. Additionally, being mindful of terrain above you late in the day is key in the event a large natural slide releases and runs to lower angle terrain or a drainage bottom.
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