|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.|
After a brief break between storms yesterday, yet another warm ‘fire-hose’ of sub-tropical moisture will be pumping our way today. Easterly winds are just picking up this morning and should reach gale force (or up to a 10 on the Beaufort Scale) by noon on the ridgetops. Precipitation has just begun as well and we can expect 1″ of rain below 1,300′ and around a foot of snow in the Alpine (another 1″ is expected tonight with a rain/snow line dropping to ~600ft). What this all means is another day of HIGH avalanche danger in the mountains.
Avalanche issues today will be similar to those seen since Christmas Eve when this series of storms began. These are: WIND SLABS, STORM SLABS and CORNICE FALLS. Most of the activity we have seen so far has been initiated in the dry snow above treeline. Several slides have been big enough to deposit large amounts of debris at the bottom of the path. Today’s storm is just as likely to create large avalanches and until we see a true break in weather, sticking to gentle slopes and areas well away from slide paths will be key.
Just because you are in the trees and out of the wind doesn’t mean the pack is stable; especially in the Summit Lake zone. Here the pack is shallower and harbors more weak layers under the recent storm snow. We went out to look at a snowboarder triggered avalanche from Saturday on Tenderfoot yesterday. What we found was a layer of buried surface hoar existing right around treeline (2,000-2,400′) that was responsible for this avalanche. More details on that HERE and HERE.
With another spike in temperatures, rain up to 1,300′ and wet snow to 2,000′, we may see additional natural wet avalanche activity below 2,000′. Many of the gullies along the Seward Highway and Seattle Ridge have slide over the past week, wet debris can be seen in the bottom of these. Although most of these slides start as dry avalanches in the Alpine and run into wet snow on the descent, some do initiate below 2,000′ as true wet avalanches. Needless to say, steering clear of runout zones is advised.
Sitting under 5-7′ of settled storm snow is a layer of old faceted snow over the Thanksgiving Rain Crust. As we pile more and more load on top of this facet/crust combo, we could see very large avalanches. Some of the large avalanche activity seen during this past week may have ‘stepped-down’ into this deeper layer. And, just one more reason to let the mountains be as these storms roll through.
Yesterday’s weather saw intermittent light snowfall above 900′ and light rain below this. Accumulation was 0-2″. Skies were overcast with a few breaks in cloud cover. Winds were moderate (averaging in the teens with gusts in the 40’smph) from an Easterly direction. Temperatures were in the mid 20’s F on the ridgetops and around 32F at 1,000′.
Overnight, temperatures have climbed to 39F at 1,000′ on Turnagain Pass (I know, yikes!) and the upper 20’s on the ridgetops. Winds are on the rise as well, averaging 40-50mph with gusts over 80mph. This is all in response to another large Pacific storm in the Gulf, which is ushering in sub-tropical moisture, and warm temperatures today. By 6pm tonight we are expecting 1″ of rain to fall below 1,300′ and up to a foot of snow at the high elevations; another 1″ of water (10-12″ snow up high) is expected tonight but the rain line should drop to ~600 (which is good news for snow at the parking lots). Winds today will be very strong – averages in the 50’smph with gusts over 90mph.
A break in storm systems tomorrow and Wednesday may allow skies to clear a bit before yet another warm/wind/wet storm arrives on Thursday/Friday.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||29||1||0.2||85|
|Summit Lake (1400′)||30||0||0||30|
|Alyeska Mid (1700′)||32||2||0.2||62|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||26||N/A||N/A||N/A|
|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|
|11/25/23||Turnagain||Observation: Tincan trees||John Sykes Forecaster|
|11/21/23||Observation: Spokane Creek||John Sykes Forecaster|