|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.|
It has been 5 days since the end of a 10-day storm cycle that brought 3-6′ of heavy dense snow and rain to the region. This snow fell on a widespread layer of buried surface hoar and unfortunately this layer continues to inhibit good bonding between the storm snow and the old March surface. As days pass, this layer of buried surface hoar is becoming more difficult to trigger. Furthermore, the fact that is sits over 3′ deep on many slopes also makes it more difficult to trigger. However, this should not lure us into thinking a slope is safe. Keep in mind thin spots in the slab, which is where an avalanche is most likely to be triggered, exist on all slopes and are tough to see and avoid – making this deep slab problem very tricky. Things to remember if heading out today:
1- No signs of instability may exist before a large slab is triggered
2- Slabs can be triggered remotely from below!
3- Several tracks may be on a slope before someone finds the thin spot
4- Daytime warming will increase chances for triggering a slab
5- All aspects are suspect
6- These slabs are large and dangerous and nothing to mess with
7- Low angle slopes continue to be your friend, with nothing steeper above you
*More details have come if from the several snowmachine triggered avalanches in the Seattle Creek drainage over the weekend. Please see the excellent write up and photos sent in to us from the close call where a snowmachiner was able to ride up and off a very large slab avalanche in Jr’s Bowl.
Large snowmachinge triggered slab avalanche in Jr’s Bowl (2nd Bowl) on Saturday, April 8th. Photos, Cory Runa.
Crown was up to 10-12′ thick – very large slab near the ridgeline where winds deposited snow during the 10-day storm cycle.
Large avalanche that was presumably triggered by a snowmachine on either April 7th or 8th on the NW aspect of Main Bowl (1st Bowl). Photo taken by Cory Runa on April 8th. Because of it’s safe and easy access, this is the avalanche that we closely investigated yesterday – flank profile and video below.
Springtime is upon us and daytime warming below 2,000′ will again soften the surface crusts at the lower elevations and on Southerly upper elevations. While the upper elevation temperatures have remained relatively steady, in the mid 20’sF, the lower elevations below 2,000′ are cooling overnight to ~30F then warming into the 40-45F range. By late afternoon watch for the snow to become saturated and unsupportable, this is the sign to move to cooler aspects. Wet loose and wet slab avalanches are still possible at these lower elevations.
Cornices are large and likely hanging close to their tipping point. Direct sunshine, a person, or a group of people on top these could be enough to cause one to break. They can be extremely dangerous on their own, but with our current snowpack, they could trigger a large slab avalanche below, making a big problem even bigger. Give cornices a wide berth from above and limit exposure under them from below.
Mostly cloudy skies coupled with instability showers along with some patches of blue sky were over the region yesterday. Over the past 24 hours, ridgetop winds have been light from an Easterly direction in the 5-10mph range and only a trace an inch of new snow has fallen. Temperatures have remained in the mid 20’s F along ridgetops and warmed into in the low 40’sF below 2,000′.
Today, we should see sunshine in most areas. Ridgetop winds are expected to be light, 5-10 mph, and from a Northerly direction. No measureable precipitation is expected. Temperatures should be similar to yesterday, rising to the low 40’s at the lower elevations below 2,000′ and remain in the mid 20’s F along the ridgetops.
A warmer air mass begins to push in overnight and beginning tomorrow, warm temperatures, sunny skies and light winds should rule the weather for the remainder of the week.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||36||trace||0||72|
|Summit Lake (1400′)||35||0||0||25|
|Alyeska Mid (1700′)||34||trace||0.03||67|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||28||SE||7||19|
|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|