Valanga

St. Regis Basin

Izzy Davis/Chris BilbreySilver Valley & Bitterroot Mountains
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Quick report

Older glide cracks that had started earlier in the season and then were reburied are making an appearance again. Large chunks of cornice are falling, and rain runnels could be seen on every slope up to 6,800'.

Observed a natural avalanche cycle, that likely failed sometime during Monday's rain event-but without getting very close to the debris it's hard to nail down for sure. An estimated window for the natural avalnches we saw would be between 3/24-3/26.

Weather

Air Temp
55
Cloud Cover
broken
Wind Loading
none
Rain Elevation
7000+
Snow Avail For Transport
none

Hottest day of the year so far, with temps in the mid 50sF and approaching 60. Partly sunny skies, with more high clouds building later in the day. Plenty of spring sun coming through.

Snowpack

In a short period during the month of March, the forecast zone received several feet of light snow. Things have changed rapidly, and we are now going on 3 days of above freezing temperatures, recent rain, sunshine, and mountain temperatures reaching nearly 60 degrees F. All of these components have aided in an abundance of meltwater running through the snowpack. On more south facing aspects, this meltwater can be seen pooling on previous crusts that are about 1 foot down, and also pooling in areas further down. This free water has created weaker grain to grain bonds and there is an elevated probability of triggering a slab avalanche on these more solar aspects - especially on slopes steeper than about 30 degrees. The water pooling was so significant, we could squeeze impressive amounts of water out of these layers. On a northeast aspect at a similar elevation, we found that the nsowpack was missing the preexisitng crusts and that instead of water pooling on crusts or interfaces, it had instead drained deeper into the snowpack- the previous cold snow seemed to help absorb the moisture like a sponge. 

Avalanche

Size
D2
Type
WL
Count
5
Aspect
NE
Trigger
N
Elevation
6200 ft

Lots of natural loose wet avalanche activity around rock bands and steep slopes. Observed loose wet avalanches on north, east and west slopes, and did not get eyes on much of the south side of the compass, but would logically guess that loose wet avalnches are naturally running on all aspects. Evidence of one large natural wet slab was observed.