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Advisory for Jan. 29

THIS Avalanche Advisory EXPIRED ON Jan 29, 2020 at 6:55 pm
Avalanche Advisory published on Jan 28, 2020 at 6:55 pm
Issued by Aaron Hartz
Bottom Line
This is a 24 hour advisory. Windslab avalanches will be the primary concern over the next 24 hours. If you see any signs of unstable snow, move to simpler and lower angle terrain
Avalanche Character 1: Wind Slab
Windslabs may exist or will build near treeline and above treeline primarily on northerly and east aspects. They will not be everywhere throughout the terrain; watch for evidence of wind transported snow on lee slopes below ridgetops and around features that catch wind blown snow. Triggering a windslab will be likely in the right terrain with avalanches size D1-D2 possible.If you see cracking in wind transported snow, this is a sign that windslabs are likely to trigger.
Avalanche Character 2: Cornice
Cornices will have the potential to be building on northerly and east aspects at ridge tops. Be cautious when approaching ridge tops and avoid walking out onto a cornice. Remember, cornice failures can also trigger an avalanche on the slope below. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive
Avalanche Character 3: Storm Slab
Storm slabs have not been a problem so far during this storm period, however as the daytime temperature warms up a bit on Wednesday, we may see the new storm snow become more slab like. This will mostly be a problem below treeline. If you see cracking in recent storm snow avoid steep, convex, and committing terrain. Storm slab avalanches, will likely be on the small side, but could have consequence in steep terrain and around terrain traps.
Snowpack Discussion
The upper and mid pack are generally showing good structure. We have no new observations from the deep pack; presumably remnants of the December weak layers are still visible along with multiple rain and melt freeze crusts.
The 1/18 rain crust is now 50 to 80 cm below the surface. Storm snow from the last two days appears to be bonding well to the older snow.
Recent Observations
A skier triggered slab avalanche on a north aspect at Paulina Peak was reported; (type not reported, likely a size D2). I recommend reading the report from Paulina. A size D1 windslab avalanche triggered by an intentional cornice drop was observed on Monday; North aspect, near treeline
Mountain Weather
Snowfall is expected to taper off, although we could see a few more inches on Wednesday. Wind is expected to be mostly out of the west and southwest on Wednesday and in the light to moderate range. The daytime high temperature could creep up to freezing or a little above on Wednesday.

This snowpack summary applies only to backcountry areas. Click here for a map of the area. This snowpack summary describes general avalanche conditions and local variations always occur. This snowpack summary expires in 48 hours unless otherwise noted.

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