Hatcher Pass

The unusual and rapid warm up that occurred earlier in the week, Monday thru Wednesday, resulted in numerous small to large wet loose avalanches and some slab activity.

For more avalanche info see Observations HERE and Thursday forecast HERE.

3.7-8 Arkose Ridge Wet Loose 3600′ SSW

3.8? Wet Loose 3000′ SW

3.8 Natural wet loose at the roadcut, entrance to Hatcher Pass 1100′ SSE

3.8 Upper Microdot Naturals, Wet Loose 4200′ SW

3.8 Microdot Naturals, Wet Loose 4500′ S

Wind slabs up to 6″ thick will be possible to human trigger at upper elevation on south through west aspects, and cross loaded features, on slopes 35º and steeper. Naturals are unlikely.

Expect NE winds to gust in the teens and 20’s mph until mid-day today and then begin to taper.

The good news is that the duration and intensity of yesterday’s wind was less than forecasted. The bad news is there is still a significant amount of low density snow on northerly aspects available for transport.  On Friday, winds were reported gusting ENE 20-33 mph for 16 hours at 4500′. On our tour Friday, winds were visibly stronger on the Arkose ridgeline and south of the forecast zone, closer to the Matanuska Valley as compared to the IM bowl.  Expect wind slabs to be larger and more sensitive at upper elevation up the Gold Mint Valley and the Arkose ridgeline.

Expect wind slabs NOT to bond well to firm, smooth crust bed surfaces that are prevalent on south to west aspects.

3.10 ENE Strong to extreme winds on Punk Spines/Arkose Ridge transporting low density snow 4500′ Friday morning.

3.10 Strong winds at ridgetop on Eldorado Bowl 4500′

A visual clue of strong winds and drifting snow is flagging or pluming at ridgelines.

Stiff snow overlying weaker snow will be easy to identify with pole or probe testing. Shooting cracks are a red flag for this problem.

Natural and human triggered Persistent Slabs will be unlikely today.

The likelihood of triggering a persistent slab has decreased significantly.  The slab/weak layer combo still exists in some locations, mostly leeward aspects where snow surfaces remained cooler after the rapid warming event Monday-Wednesday. Finding a shallow spot to trigger one of these slabs will be challenging but not impossible.

In isolated locations and extreme terrain at upper elevation, it may be possible to trigger a wind slab on a west aspect that steps down into the persistent slab.

This same senario will be highly unlikely on south aspects due to the impenetrable crusts that have essentially locked up the snowpack.

Due to the return of cooler daytime temps, solid freezing temperatures overnight, combined with northerly winds, conditions have once again shifted abruptly. Thursdays shift towards cooler weather has left firm bulletproof, slide for life conditions on steep southerly aspects, and breakable crusts on mellower terrain.

Unless you have ski racing experience on blue ice in the East Coast and/or excellent edging technique, I’d recommend ski crampons for skinning uphill on steep southerly aspects, or just avoid southerly. Expect crusts of all sorts on East through West aspects at all elevations. On Friday, crusts did not soften throughout the day.

Expect this avalanche problem to rear its head later in the season. With so many buried crusts in the snowpack, especially on southerly aspects, we can expect the persistent slab problem to become more reactive with future loading events.

This photo shows the current snowpack structure on south aspects with lots of buried crusts and moist snow from rapid warming this week.