|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 was one human triggered avalanche reported to us yesterday. This was on the smaller side, 10 inches thick and 30 feet wide. It was a soft wind slab on the West face of Magnum, pictured below. With another 2-4″ of snow falling last night along with easterly winds, we can expect similar avalanche conditions today.
Observers reported intentional human triggered soft wind slab avalanche on west face of Magnum at 2500′
Photo credit: Emily Sullivan
|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
All wind slabs are suspect for being unstable. The new snow and wind events over the last three days in combination with buried weak layers has created the recipe for avalanches. Wind effected slopes and cross loaded gullies in the treeline and alpine are the most concerning.
Keep a close lookout for windloading and areas where the top foot of snow is stiffer than the snow underneath. Any shooting cracks in the snow or whumpfing (collapsing) are clear signs that layer of snow could avalanche.
Once the newer snow becomes more consolidated, it could become cohesive and form a slab. Once it does, we could start seeing an increase in avalanche activity.
Sluffs: In steeper areas, sluffs could entrain enough snow to knock a person off their feet. Give extra caution while traveling above cliffs and rocky terrain.
Cornices: With winds capable of transporting snow and loose snow available for transport, cornices continue to form and build throughout the region. Give cornices a wide margin.
Glide cracks and avalanches are still possible. New snow and wind is likely filling in or bridging glide cracks throughout the region and they could be more difficult to see. Remain prudent when visibility is low, and avoid being underneath glide cracks when possible.
Yesterday: Cloudy and obscured skies with 2″-4″ of snow overnight at sea level. Ridgetop winds from the east at 10-35mph. Temperatures were below zero and into the teens.
Today: Mostly cloudy skies with intermittent snowfall today may provide an additional 1-3″ before this system pushes out. Ridgetop winds from the east will likely blow from 5-15mph gusting to 35mph. Temperatures will range from 0°F to the low 20’s today.
Tomorrow: Cloudy skies with continued intermittent light snowfall. Temperatures should bump back up to the teens and low 20°F as the next front approaches on Sunday afternoon bringing another round of precipitation into Monday.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||5||3||0.3||38|
|Summit Lake (1400′)||3||3||0.2||13|
|Alyeska Mid (1700′)||4||4||0.2||30|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||N/A*||N/A*||N/A*||N/A*|
*Rime has covered the wind sensor on Seattle Ridge.
|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|