|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.|
|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|
Wow! Getting to see the extent of the St. Patty’s Day avalanche cycle was impressive and scary. With a window of good visibility yesterday large, deep avalanches that occurred 3.17 and 3.18 were observed across the advisory area. Additionally and notably two large avalanches were observed running naturally yesterday. The Five Sisters avalanche path in Portage ran in the morning with a 10+ foot crown and a slide in Main Bowl on the back side of Seattle Ridge was observed running in the afternoon. Today the next storm system is forecast to impact the area. Temperatures are already above freezing in the Alpine, rain is expected to fall to 2500′ and winds are already gusting into the 70s on Sunburst. There is a buffet of avalanche issues today and the potential for large to very avalanches makes travel in avalanche terrain including runouts not recommended. The crust that formed with cool temperatures Monday night could eventually break down and there is either colder snow that could be over loaded as it becomes saturated or at lower elevations already very saturated snow that could move. Above the rain/snow line new snow and wind will add stress to the snowpack and cornices are large and dangerous. Investigating the very large avalanche on Tincan yesterday showed that avalanches are breaking back to the March 8th new/old snow interface made up of small facets and buried surface hoar. Multiple feet of snow now rest on top of this layer and avalanches today and tomorrow may still break down at this weakness. The snowpack will need time to adjust to all the loading from the March barrage of storms. Give it some time and enjoy other activities away from the mountains!
Natural avalanche in Main Bowl on the backside of Seattle Ridge observed running yesterday afternoon, 3-19-19. Photo: Travis Smith
Five Sisters avalanche path in Portage Valley was observed running yesterday morning, 3-19-19.
The 3.18.19 Tincan avalanche. Photo from Seattle Ridge: Travis Smith.
Yesterday: Partly sunny with temperatures in the 20Fs to 40Fs depending on elevation. Winds were light and easterly. Clouds moved in overnight and temperatures were in the 30Fs and 40Fs. Easterly winds increased blowing 30-40 mph with gusts into the 70s.
Today: Rain and snow throughout the day with close to an inch of water in the forecast. Rain/snowline is expected to be around 2500′. Temperatures will be in the high 30Fs to high 40Fs, with Alpine temperatures already in the mid 30Fs. Winds will be easterly 30-40 mph with gusts into the 60s and 70s. Rain and snow continue overnight with unseasonably warm temperatures and strong winds.
Tomorrow: The warm wet weather continues into Thursday. Expect more of the same. This active pattern extends into the weekend with a brief break on Saturday and another storm Sunday.
*Seattle wind sensor was cleared and started reporting 4 pm yesterday, data is incomplete.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||36||0||0.1||86|
|Summit Lake (1400′)||35||0||0||29|
|Alyeska Mid (1700′)||35||0||0.08||76|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||30||SE*||4*||24*|
|12/02/23||Turnagain||Observation: Seattle Ridge||Schauer / Keeler Forecaster|
|12/02/23||Turnagain||Observation: Tincan South Side||Anonymous|
|12/02/23||Turnagain||Observation: Eddies up track||Luc Mehl|
|12/01/23||Avalanche: Sunburst||John Sykes Forecaster|
|12/01/23||Turnagain||Observation: Eddie’s trees||Anonymous|
|12/01/23||Turnagain||Observation: Turnagain – God’s Country||Graham Predeger Forecaster|
|11/30/23||Turnagain||Avalanche: Tincan Trees||Kakiko Ramos-Leon|
|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|