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The avalanche danger is CONSIDERABLE above 2500′. Strong easterly winds are increasing through the day, making human-triggered avalanches likely and natural avalanches possible. A wind slab avalanche failing 1-2′ deep in freshly wind-loaded snow may trigger a very large avalanche on weak snow buried 3-6′ deep. Dangerous avalanche conditions will require cautious route finding, which means avoiding steep avalanche terrain. The danger is MODERATE between 1000′ and 2500′, where the winds won’t be quite as strong and the deeper weak layers are less likely to be an issue. The danger is LOW below 1000′.
Join us at the Girdwood Brewing Co. from 5:30-7:00 p.m. on Thursday, Jan. 19 for the second Forecaster Chat of the season. CNFAIC forecaster Andrew Schauer will open the night with an overview of the state of the snowpack, followed by a discussion on how safe terrain management changes depending on the type of avalanche problem at hand. More details here.
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 has not been any avalanche activity that we are aware of since Saturday’s very large avalanche on Cornbiscuit (details here). Wendy saw evidence of recent natural activity near Johnson Pass yesterday (see photo below), and I saw an avalanche that failed on a layer of facets below a thin crust on a wind-loaded slope in Snug Harbor (details here).
Natural avalanches in our middle elevation band in the Johnson Pass area. Photo taken 01.09.2023
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 |
The weather is picking up today, and it will increase the chances of a person triggering an avalanche. Easterly winds have started increasing overnight, blowing 15-25 mph with gusts to 40 mph at ridgetops, and are expected to continue to increase today. We are expecting to see average speeds of 20-30 mph with gusts of 30-40 mph. This wind may be accompanied by some light snow, but it will most likely only mean a trace to an inch today and 3-5″ tonight.
Fresh wind slabs will be forming on a widespread layer of surface hoar and near surface facets, which exists virtually everywhere in our advisory area from valley to ridgetop. That will make new wind slabs especially reactive, making human-triggered avalanches likely and naturals possible. These avalanches will be 1-2′ deep on average, but what makes them even more dangerous is the potential for a small avalanche near the surface triggering a very large avalanche on the problematic layer of facets buried near the Thanksgiving crust. More on this in Problem 2 below.
Wind slabs will be deeper and more reactive in the alpine, where winds are blowing the hardest. Be wary of slopes just below ridgelines, convexities, or in cross-loaded gullies. Given the potential for wind slab avalanches stepping down to deeper layers, it is best to avoid steep avalanche terrain entirely.
This avalanche in the V-Max area near Snug Harbor occurred on a wind loaded slope and failed on a layer of facets below a thin crust. 01.09.2023
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 |
The wind slabs may be more likely today, but the Thanksgiving crust/facet layer is scarier. With the current setup, it is hard to say which problem is the primary concern. Are wind slabs more likely? Absolutely. Alternatively, can a person trigger an avalanche 3-6′ deep on a weak layer that connects multiple terrain features across thousands of feet? Also yes. We clearly have two avalanche problems that are giving us cause for concern, and the only way to manage risk with a setup like that is by taking a big step back with terrain. This is a scary setup, and we have seen multiple examples of its potential to make really big avalanches (details from Seattle Ridge here and Cornbiscuit here). For now, the safe bet is to stay off terrain 30 degrees or steeper, and give this layer more time to heal.
If the video below doesn’t load in your browser you can view it here.
Yesterday: Temperatures reached the upper 20’s F at higher ridgetops and low 30’s F at lower elevations after a colder start to the day. Winds were blowing 10-25 mph out of the east, with the strongest winds overnight and gusts to 40 mph. Skies were mostly cloudy with some spotty snow showers but no measurable precipitation.
Today: Winds are expected to continue to increase through the day into the night before calming down early tomorrow morning. As of 6 a.m., winds are blowing 15-25 mph out of the east, with gusts to 40 mph. We will likely see winds bump up to 20-30 mph through the day. High temperatures should be in the upper 20’s to 30 F under partly to mostly cloudy skies. We could see some light snow during the day, but accumulation will most likely amount to only a trace or maybe an inch during the day. For any precipitation that does fall, rain line is expected to be between 500 and 1000′.
Tomorrow: Chances of precipitation increase tonight, but it is looking like the advisory area will only receive 3-5″ snow by tomorrow morning. The rain line should be around 500′. Strong easterly winds should back off late tonight, with calm conditions tomorrow. High temperatures will be in the mid to upper 20’s F with lows dropping back to the low 20’s F. Skies will be mostly cloudy during the day with improving visibility through the day.
PRECIPITATION 24-hour data (6am – 6am)
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
---|---|---|---|---|
Center Ridge (1880′) | 32 | 0 | 0 | 56 (est.) |
Summit Lake (1400′) | 24 | 0 | 0 | 32 |
Alyeska Mid (1700′) | 31 | 0 | 0 | 49 |
Bear Valley – Portage (132′) | 31 | rain | 0.2 | – |
RIDGETOP 24-hour data (6am – 6am)
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
---|---|---|---|---|
Sunburst (3812′) | 24 | ENE | 15 | 42 |
Seattle Ridge (2400′) | 27 | SE | 10 | 20 |
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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