After several days of snowy weather, low visibility and a natural avalanche cycle, mostly clear skies are expected today. This will make travel above treeline inviting. If you are headed out in the backcountry please understand there are dragons lurking in the snowpack. Two dragons to be exact: 1) a layer of buried surface hoar sits 1-2′ below the surface and is showing signs of being reactive, 2) weak snow near the ground exists at elevations above 3,000′. These issues are also being seen in the Summit Lake region.
The New Year’s storm that began Dec 31st and ended yesterday, Jan 3rd, added 1-2′ of snow in most areas, possibly more at the higher elevations. This snow fell on a layer of surface hoar and near surface facets, creating a persistent slab problem. Rain fell up to 2,300′ at one point during the storm, which has formed crusts in the top foot of the snow at elevations below 2,000′. Above ~2,000′ where moist to dry snow exists without crusts are where triggering an avalanche is most likely. Things to keep in mind:
1- Human triggered avalanches 1-2′ thick are most likely above 2,000′
2- Remote triggering from the top, side or bottom of a slope is also likely
3- Avalanche size is expected to be large enough to bury and kill a person
4- The larger the slope the larger the avalanche
Performing quick pits to assess the bonding of the New Year’s snow to the weak snow below is a great idea, but not something to completely hang your hat on. The buried surface hoar may have been blown down in your pit, yet remains lurking on the slope you plan to ride. Today and tomorrow are days to be extra cautious as there are too many signs pointing to an unstable snowpack. Along with the buried surface hoar problem, wind slabs and cornice falls are possible along ridgelines. One of these avalanches can trigger a larger avalanche below.
Check out these videos. The first is the general snowpack set-up, the second is a close up/snow motion video of the collapse and propagation of the buried surface hoar found yesterday on Sunburst:
Runnels from the rain exists around 1,600′. At these lower elevations the wet snow is freezing into a crust and triggering an avalanche is unlikely.
In the Alpine, above 3,000’, weak sugary snow (basal facets) sits near the ground. The storms over the past few days have added additional load to slopes that already have a hard slab 3-5+ feet thick. At these elevations, human triggered, large and dangerous deep slab avalanches ARE still possible. This is a high consequence avalanche problem that is impossible to outsmart and can take a long time to heal. Keep this in mind as improving visibility in the next few days may allow for travel to the Alpine. It is really important to remember that triggering an avalanche in the upper layers of the snowpack may then initiate a deep slab avalanche. Cautious route-finding is essential. This includes thinking about the remote trigger potential from below.
Obscured skies and light snow showers filled the area yesterday. Snowfall yesterday at the mid elevations accumulated to 2-3″ at most locations with .2-.3″ of water equivalent. An additional couple inches is likely to have fallen in the upper elevations. Winds turned Westerly yesterday and were light in the 5-10mph range during the past 24-hours. Temperatures have dropped overnight with clearing skies and are sitting in the mid-20’s at 1,000′ and near 20F on ridgetops.
Today, mostly clear skies are forecast with valley fog to be expected. Ridgetop winds will be Westerly in the 5-10mph range. Temperatures will continue to decrease to the teens along ridgelines and the mid 20’sF at 1,000′ as cold air streams in with the winds.
Another clear sky day is on tap for tomorrow before a round of snow (and it looks like snow to sea level) moves in on Saturday – stay tuned!
*Seattle Ridge anemometer is rimed.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||30||1||0.2||46|
|Summit Lake (1400′)||28||3||0.3||16|
|Alyeska Mid (1700′)||30||1||0.3||39|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||*n/a||*n/a||*n/a|
|12/10/19||Turnagain||Avalanche: Tincan and Sunburst from the air||CNFAIC Staff|
|12/10/19||Turnagain||Observation: Tincan||Nancy Pfeiffer|
|12/08/19||Turnagain||Avalanche: Tincan||Ryan Van Luit Forecaster|
|12/06/19||Turnagain||Avalanche: Sunburst||Billy Finley|
|12/04/19||Turnagain||Observation: Sunburst||A.Johnston-Bloom/ W.Wagner/ R.Van Luit Forecaster|
|12/03/19||Turnagain||Observation: Hippy Bowl||Nick Langowski|
|12/01/19||Turnagain||Observation: Tincan, All elevations||Eric Roberts|
|12/01/19||Turnagain||Observation: Tincan||Andy Moderow|
|11/30/19||Turnagain||Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge||Eric Roberts|
|11/29/19||Turnagain||Observation: Sunburst Ob #2||Aleph Johnston-Bloom Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: email@example.com
|Area||Status||Weather & Riding Conditions|
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