Snowpack Summary published on February 27, 2020 @ 6:01 am
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Issued by Andy Bond - Taos Avalanche Center

bottom line:

Persistent slab avalanches on NE through E and SE aspects near and above treeline remain the focus over the next three days.  Recent loading from W / NW winds have transported snow into stiffening cohesive slabs that rest on top of faceted crusts deeper down in the snowpack.  Take the time to dig down and assess whether the slope you plan to play on has this poor snowpack structure.  

Avalanche Character 1: Persistent Slab
Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

Persistent weak layers on NE through East and SE aspects near and above treeline will continue to need time to adjust to added load from wind transported snow. A strong over weak snowpack structure can be found on many of these slopes.   Solar aspects have a series of faceted crusts that now has a cohesive slab resting on top (See Video). We continue to find a highly variable snowpack, take the time to dig down into the snow to assess if the slope you plan to play on harbors this poor snowpack structure.

Pay attention to obvious clues like loud audible whumf's and shooting cracks as these are indications that you've found this strong over weak snowpack structure. Any avalanche triggered in these deeper layers could be large and destructive. 

Snowpack Discussion

Strong W / NW winds Monday and Tuesday transported the recent snow onto leeward slopes and cross-loaded gullies above treeline and areas near treeline that are exposed to winds.  On Tuesday we were remotely triggering this wind drifted snow on East aspects on a near surface layer buried beneath a crust from the last round of high pressure that proceeded this last storm (See Video).  We've taken down wind slabs as a problem over the next three days but you may be able to find hollow drummy sounding wind slabs above treeline on NE through SE aspects. Pay attention to a stiffening of the snow surface underfoot and obvious clues like shooting cracks on the surface.  A smaller wind slab avalanche has the potential to step down into deeper faceted layers creating a larger more destructive avalanche.     

Cornices are starting to get bigger with this last round of wet snow and strong winds.  If traveling on ridgelines, give cornices a wide berth as we are finding them breaking back further than expected. Cornices can be a large trigger to get the slope beneath them to avalanche.

Northeast through Southeast aspects have been where we've seen the most avalanche activity over the last several storm cycles.  This is also where we've had the most of amount of loading with West and Northwest winds.  A series of faceted crusts can be found on these slopes that have formed from warm temperatures and strong sun during high pressure periods earlier in the winter.  

In recent snowpits and surveying of snowpack depths we are finding a high level of spatial variability. Some slopes are surprisingly deep over 2 + meters of snow while others have less than 1.5 m.   In areas where we have these shallow snowpacks our persistent weak layers haven't been healing as quickly. (See Video) Snow from the last couple of weeks and strong winds have formed cohesive slabs on top of weak faceted snow leading to this poor snowpack structure.

Above treeline in many places we are finding persistent weak layers that are insulated by hard stiff wind slabs or very firm crusts overlying them that are able to support the weight of a skier or rider and may be more stubborn to trigger. It will most likely take you to find a "sweet spot" where these hard slabs or crusts are thinner and weaker to be able to impact these faceted layers.   As we have a lot of spatial variability, take the time to dig down into the snowpack to see if the slope you plan to play on harbors this poor snowpack structure.

It's been another storm where higher elevations have received the bulk of the snow. Below treeline, we've seen our snowpack continue to get shallower with warming temperatures and lack of snow to build up a deepening base. At these elevations we have an overall shallow snowpack that has been decomposing and on some slopes is made up of unsupportable facets to the ground. What we continue to lack though is a cohesive slab above these weak layers

Wind sheltered areas will provide the safest and best skiing and riding. With a warming trend and strong sun over the next three days, we could see small loose snow "sluffs" in steeper terrain. 

 

The BCA Beacon Basin park is up and operational at the base of the Chair 4 lift at Taos Ski Valley.  This is a great way to brush up on your avalanche transceiver skills. 

Stay safe out there and our next update will be Sunday Morning.  If you get out, shoot us an observation as this only helps the forecast.

recent observations

Moderate NW winds continue to transport snow on Tuesday at ridgelines.  Went to Long Canyon to check out what the westerly winds have been doing on East aspects near and above treeline.  I remotely triggered an avalanche that was failing on near surface facets below the crust that formed from the last round of high pressure that formed before this last round of snow.  We were getting loud audible collapses during the tour above 11,500' where more snow had fallen.  We triggered several avalanches today on East aspects.  While traveling on ridgelines or cornices are really starting to grow with the wet snow and winds.  We had cornices breaking further back than expected and triggering avalanches in the slopes beneath.   

East aspect in Long Canyon, Remotely triggered avalanches from Tuesday from the ridgeline above failing on a near surface facet layer below a melt-freeze crust from the high pressure prior to the storm

A cornice that broke while we were traveling on the ridgeline 

 

We continue to find varying snowpack depths. This is a shallow snowpack on a North aspect where we have faceting snow and depth hoar on the ground.

Weather and CURRENT CONDITIONS
weather summary

It should be beautiful weather here in the land of enchantment over the next several days. Sunny skies with a dry northwest flow for Thursday and Friday.  Temperatures will progressively get warmer through Saturday. Moderate NW winds will shift to the West on Saturday ahead of a possible storm system late Sunday night.   

Weather observations from the Wheeler Peak Wilderness between 9000 ft. and 13000 ft.
0600 temperature: 13 deg. F.
Max. temperature in the last 24 hours: 22 deg. F.
Average wind direction during the last 24 hours: NW
Average wind speed during the last 24 hours: 14 mph
Maximum wind gust in the last 24 hours: 25 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 71 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Albuquerque NWS
For 9000 ft. to 10000 ft.
Today Tonight Friday
Weather: Sunny Mostly Clear Sunny
Temperatures: 36 deg. F. 12-19 deg. F. 39-44 deg. F.
Wind Direction: NW NW W
Wind Speed: 5-15 5-15 5-15
Expected snowfall: 0 in. 0 in. 0 in.
For 11000 ft. to 13000 ft.
Today Tonight Friday
Weather: Sunny Mostly Clear Sunny
Temperatures: 24-30 deg. F. 11-16 deg. F. 31-37 deg. F.
Wind Direction: NW NW NW
Wind Speed: 10-20 5-15 5-15
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

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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