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The avalanche danger is MODERATE today on all aspects above 1,000′. Watch for fresh wind slabs that could form with 2-4″ of new snow and moderate southerly winds. These could be in the 6-10″ deep range and be possible to trigger on wind loaded slopes steeper than 30 degrees. Additionally, there is still a chance a person could trigger a larger slab (10-20″ deep) that breaks on weak snow buried by the April Fools’ Storm. The danger is LOW below 1,000′ where triggering an avalanche will be unlikely.
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 |
After a few days of mostly quiet weather and sunshine, there is a weak storm system moving over the region today. We are looking at light to moderate snowfall this morning adding 2-4″ by the afternoon. This system is pushing in more from a southerly direction. Ridgetop winds actually look to blow up to 20mph from the south this afternoon. With a few new inches of snow and any pre-existing snow the wind can move, we can expect to see small wind slabs forming in the higher terrain and exposed areas in the trees. I’d expect them to be in the 6-10″ deep range. They should be easy to pick out by watching for active wind loading and cracking in the snow around you.
With many southerly facing slopes harboring a sun crust from the weekend, the southerly winds may not be able to transport much older snow. However, we all know how the wind can be quite squirrely through the terrain, so look for wind loading on all aspects. Shallow sluffs may also be seen today, but will be small due to the meager new snow amounts. If the sun pops out this afternoon/evening, watch for sun triggered moist sluffs in the new snow. Again, these should not pack much punch.
Persistent Slab Avalanches: About a foot under the snow surface (plus or minus 6″ depending on your location), is the old surface from the end of March. This surface caused a bunch of avalanches, all around a foot deep, during and just after the April Fools’ Storm. The old surface was composed of small buried surface hoar and some small facets. In many places this thin weak layer was sitting on a crust – just like in the photo and video below. Over the last two days we have not been able to find it reactive anymore, even in areas near where avalanches did occur a couple days earlier. That said, we should still keep this layer in mind moving forward in case there are some booby traps out there. This is true on northerly slopes currently, but also on southerly slopes on hot days when the surface crusts melt and weaken the pack.
Snowpit from yesterday in Seattle Ck Drainage, W aspect, 2,200′. We could not get the April Fools’ Day storm snow to react to shear. It had bonded in this area. 4.4.22.
Glide Avalanches: Glide cracks keep slowly oozing open through the region and a few have released. There is one impressive crack on the SW face of Eddies and other areas easily seen from Turnagain Pass. Remember to watch for these and limit any time spent under them. They can avalanche at anytime.
Glide crack on the east facing slopes of Main Bowl. 4.4.22.
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 |
Buried anywhere from 3-6 feet deep in the snowpack are a few older layers of buried surface hoar and near surface facets from March. It has been 10 days since the last known avalanche released on one of these layers. Although we are still keeping track of it, triggering one of these large slabs is becoming unlikely. This is due in part because it is buried so deep and difficult to trigger, but also due to the weak layers slowly gaining strength with time. However, rapidly warming temperatures or a new load of snow/rain could reactive the layers and we’ll be looking for this.
Yesterday: Partly sunny skies were over the region with light easterly ridgetop winds. Temperatures climbed to 40F at the low elevations and near 30F along the higher terrain.
Today: Cloudy skies have moved in overnight and light snowfall is expected today to sea level. Accumulations should be in the 2-4″ range with another 1-2″ possible through tonight. Ridgetop winds are forecast to be 10-20mph from the southeast. Temperatures should say in the low 30’sF at the lower elevations and in the low 20’sF along the ridgelines.
Tomorrow: Cloudy skies with another inch or two of snow could fall on Wednesday. Ridgetop winds look to be increasing from the south into the 20-30mph range as a front pushes in from a more souther direction.
PRECIPITATION 24-hour data (6am – 6am)
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
---|---|---|---|---|
Center Ridge (1880′) | 32 | 0 | 0 | 118 |
Summit Lake (1400′) | 33 | 0 | 0 | 39 |
Alyeska Mid (1700′) | 34 | 1 | 0.4 | N/A |
RIDGETOP 24-hour data (6am – 6am)
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
---|---|---|---|---|
Sunburst (3812′) | 21 | E | 8 | 24 |
Seattle Ridge (2400′) | 25 | SE | 7 | 15 |
Date | Region | Location | Observer |
---|---|---|---|
05/13/24 | Turnagain | Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South | H Thamm |
05/13/24 | Turnagain | Observation: Turnagain Pass non-motorized side | Amy Holman |
05/12/24 | Turnagain | Observation: Warm up Bowl | Tony Naciuk |
05/07/24 | Turnagain | Observation: Turnagain Pass Wet Slabs | A S |
04/29/24 | Turnagain | Avalanche: Turnagain aerial obs | Tully Hamer |
04/27/24 | Turnagain | Observation: Johnson Pass | Noah Mery |
04/23/24 | Turnagain | Observation: Turnagain Sunny Side | Travis SMITH |
04/21/24 | Turnagain | Observation: Bertha Creek | Anonymous |
04/20/24 | Turnagain | Avalanche: Spokane Creek | Schauer/ Mailly Forecaster |
04/16/24 | Turnagain | Observation: Cornbiscuit | Krueger / Matthys Forecaster |
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