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The avalanche danger is CONSIDERABLE for all elevations. In the last 48 hours there has been heavy snow, rain and strong winds. Human triggered slab avalanches are likely on slopes 30° and steeper and will increase in likelihood with elevation. We are at the tail end of a significant storm, which means cautious route-finding and conservative decision-making are essential today.
SUMMIT LAKE: The snowpack is generally thinner and weaker in the Summit Lake region and 1-2′ of snow fell during this storm. This means it may be even easier to trigger an avalanche on a mid-pack buried weak layer or near the ground.
SEWARD/LOST LAKE: This region saw heavy rain and snow yesterday and there is no snowpack information for this area yet. Extra caution is advised as more data is collected.
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 |
If venturing out today in the soggy mountains caution is advised. Monday night a natural avalanche cycle occurred in upper elevation terrain near Girdwood and in Portage. Yesterday there were avalanches observed running in the Moose Pass zone during the intense rain. There were no reports of avalanches in Turnagain Pass or Summit Lake but we have not had much visibility to assess. Depending on location, between 1-3′ feet of new snow has fallen at upper elevations. In addition, rain fell to around 2000′ (maybe higher). Turnagain Pass and Girdwood were spared the heavy rain Portage and Moose Pass south to Seward received. The most intense winds were Monday evening but remained steady yesterday at ridgeline stations, blowing from the east 20-30 mph and gusting into the 40s and 50s.
As I like to say there is a buffet of avalanche issues to think about today. Storm snow avalanches, such as wind slabs along ridgelines, storm slabs in the sheltered zones, cornice falls and wet loose (push-a-lanches) in the saturated snow should all be viewed as likely today. It’s a day to carefully evaluate terrain and consequences if an avalanche does release. We need to give the mountains time to adjust. Low angle slopes without steep slopes above are great ways to enjoy the new heavy snow without worry.
Red flags to watch for:
– Recent avalanches, from today and was there any avalanche activity during the storm?
– Whumpfing (collapsing) of the snowpack, sure sign to avoid avalanche terrain period.
– Shooting cracks, likely to be seen near ridgelines where the wind has formed wind slabs.
Storm totals (beginning Monday night through 6am Wednesday morning)
As the storm moves on and the temperatures cool the good news is the new snow should bond relatively quickly. From what we know, the pre-existing snow surface lacked any persistent type of snow grain and was mainly wind slab and settled powder. As always however, the snowpack is guilty until proven innocent and there are always surprises out there – we can’t get caught being over confident.
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 |
We have been concerned about a skier or snowmachiner triggering a large destructive avalanche that fails near the ground on the weak October snow. We have not seen avalanche activity on this layer recently and in most of forecast area it is now buried more than 6′ deep. However, as the storm moves out and we get more visibility this week, we will be looking for signs of any natural avalanches on this layer and will continue to ask the question, ‘If I hit a shallow spot on my machine or skis could I still trigger a deep slab avalanche?’ Towards the southern end of Turnagain Pass and in Summit Lake the snowpack is shallower and potentially more sensitive to triggering an avalanche. In Summit Lake we have also found a layer of buried surface hoar in protected areas that may also be an issue. We have no snowpack information for the Lynx Creek and Johnson Pass area which is now open. This lingering ‘what if‘ about deep slabs is another great reason to keep it mellow today. Allow the snowpack time to adjust to all this recent loading. As said above, we are in the guilty until proven innocent stage.
Yesterday: Skies were overcast with rain/snow showers throughout the day. Rain/snowline was approximately 2000′ and maybe higher. There was heavy rain at times in Seward and Portage. Winds were easterly blowing 15-25 mph gusting into the 40s and 50s. Temperatures were in the high 30°Fs and low 40°Fs at sea level and high 20°Fs in the Alpine. Overnight rain/snow showers, elevated easterly winds and warm temperatures continued.
Today: Skies will remain overcast and rain and snow showers continue today. As temperatures drop rain/snowline will come down from around 2000′ to sea level. Temperatures will start out in the high 30°Fs to mid 40°Fs at sea level and the high 20°Fs in the Alpine and cool to the the low 20°Fs and teens overnight. Winds will be easterly 10-20 mph gusting into the 30s and shift to the south/south west overnight and decrease.
Tomorrow: Skies are forecast to be partly cloudy with a chance of snow showers, temperatures in the teens and 20°Fs and light southwest winds. There is a pause in the stormy weather with snow potentially returning Sunday.
PRECIPITATION 24-hour data (6am – 6am)
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
---|---|---|---|---|
Center Ridge (1880′) | 36 | 0 | 0.7 | 63 |
Summit Lake (1400′) | 33 | 0 | 1.0 | 26 |
Alyeska Mid (1700′) | 35 | 0 | 0.44 | 59 |
RIDGETOP 24-hour data (6am – 6am)
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
---|---|---|---|---|
Sunburst (3812′) | 27 | NE | 22 | 55 |
Seattle Ridge (2400′) | 30 | E | 12 | 24 |
Date | Region | Location | Observer |
---|---|---|---|
10/14/24 | Turnagain | Avalanche: Tincan | CNFAC Staff |
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 |
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