|Travel Advice||Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.||Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.||Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.||Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.||Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.|
|Likelihood of Avalanches||Natural and human-triggered avalanches unlikely.||Natural avalanches unlikely; human-triggered avalanches possible.||Natural avalanches possible; human-triggered avalanches likely.||Natural avalanches likely; human-triggered avalanches very likely.||Natural and human-triggered avalanches certain.|
|Avalanche Size and Distribution||Small avalanches in isolated areas or extreme terrain.||Small avalanches in specific areas; or large avalanches in isolated areas.||Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.||Large avalanches in many areas; or very large avalanches in specific areas.||Very large avalanches in many areas.|
There were three wind slab avalanches triggered by skiers/snowboarders yesterday. Two on the Sunburst SW aspect on a wind loaded rollover and one on a westerly aspect of Tincan. All were between 2,700’ and 3,000’ in elevation and were small to medium in size – a few more details HERE. We have also had more reports and photos come in of older natural wind slabs that were likely triggered Thursday morning (Todd’s Run, N shoulder of Tincan Ridge and SW Sunburst).
During the past week we have had moderate to strong winds from all directions that have created an extremely variable snowpack. The riding conditions are not something to write home about and neither are the avalanche conditions. Areas that are scoured to the rocks sit right next to wind loaded slabs with the potential to release.
Good travel practices and thoughtful terrain management are key – a few important ones for today:
1- Expose only one person at time
2- Watch for recent avalanches
3- Don’t discount collapsing and whumphing
The slabs mentioned above are taking a long time to heal because they are sitting on weak faceted snow formed during the November/early December cold spell. Faceted snow is very tricky and there is way too much of it in our pack. It can become dormant for a while once the pack adjusts to a new load, then with a little wind or snow, rear its head – this is pretty much what we have seen this season so far. Just remember when you are dealing with facets and persistent weak layers (including surface hoar) they are “guilty until proven innocent”.
Below treeline the snowpack has been sheltered from the wind and has broken down to becoming one unconsolidated unit. There are a multitude of weak layers but there is not a slab on top.
Temperatures have PLUMETED to a new seasonal low on the ridgetops. Sunburst and Seattle Ridge have dipped to -5F and -3F this morning where they are expected to increase only a few degrees today. There is not much of an inversion as sea level and parking lot temperatures hover between 5F and -10F. The light NW winds that were near 10mph overnight look to pick up to the 25mph range by this afternoon which should keep things feeling quite cold.
Our hopes for more snow this week is diminishing as the low pressure system moving into the Gulf on Tuesday looks to dig further south and just brush our neck of the woods. We could get a few flurries that spill over but stay tuned in case things change in our favor.
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).
Graham will issue the next advisory Monday morning, December 17th.
|11/27/23||Turnagain||Avalanche: Tincan Ridge||Schauer/ Stiassny Forecaster|
|11/26/23||Turnagain||Observation: Road report: Slide with dirt on Repeat offender||Anonymous|
|11/26/23||Turnagain||Observation: Pete’s North||Ben Sullender|
|11/25/23||Turnagain||Observation: Tincan trees||John Sykes Forecaster|
|11/21/23||Observation: Spokane Creek||John Sykes Forecaster|
|11/19/23||Turnagain||Observation: Magnum – PMS Bowl||Schauer/ Cullen/ Jonas Forecaster|
|11/19/23||Other Regions||Observation: Sunnyside/Penguin||Jose Ramos-Leon|
|11/19/23||Turnagain||Observation: Eddies||Andy Moderow|