Seward Highway: A large natural avalanche put 10-15′ debris on the Seward Highway north of Girdwood early this morning. No people were involved with the incident.
|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 latest in our parade of storms moved through the area last night, bringing 6-12″ snow to Girdwood and 4-8″ snow to Turnagain Pass and Summit Lake. Easterly winds have been blowing 15-25 mph at ridgetops with gusts of 35-45 mph, making for dangerous avalanche conditions. It is likely a person could trigger an avalanche up to 2′ deep, especially on slopes with fresh wind slabs. Upper-elevation slopes will have the most reactive snow with the potential for the biggest avalanches. Keep in mind, with up to a foot of new snow in the mountains near Girdwood it may also be possible to trigger a storm slab avalanche on sheltered slopes.
Clouds are expected to break up through the day today, with winds already starting to die down this morning. Don’t let the fair weather catch you off guard- new wind slabs will be reactive through the day. If the sun ends up making an appearance, we will likely see some solar-triggered activity. On the small side this could look like rollerballs falling off trees and rocks, but there is also the potential that small wet loose avalanches will trigger bigger slabs. Be careful with your terrain choices, avoiding steep slopes near ridgelines, below convex rolls and in steep gullies, and be aware of the terrain above you. Pay attention to the classic warning signs of dangerous avalanche conditions- shooting cracks, fresh avalanche activity, and collapsing. With one large avalanche putting debris on the highway just north of Girdwood early this morning, we know we are dealing with a dangerous setup.
Loose wet avalanches: Mixed rain and snow up to 1000′ will make loose wet avalanches possible in the lower elevations.
Cornices: With continued snowfall and sustained moderate winds, cornices continue to get bigger and more sensitive. As always, give them plenty of room when traveling above ridgelines, and limit time spent below them.
There are multiple layers of weak faceted snow associated with crusts that formed earlier in the season that are still giving us cause for concern in the areas with a relatively thin snowpack surrounding our forecast zone. We’ve seen poor snowpack structure in the Crow Creek area near Girdwood, the south end of Turnagain Pass towards the Lynx Creek and Silvertip Creek drainages, and throughout the Summit Lake area. This setup produced avalanches during the avalanche work in Summit Lake on Wednesday, and we saw evidence of natural activity in the Summit area as skies cleared for a moment yesterday.
The good news is that this layer does not appear to be a widespread concern for our core advisory area. If you are planning on getting out in the periphery zones, don’t forget about this poor structure. A relatively small avalanche triggered near the surface will have the potential to step down to weak snow buried deeper in the pack, making a large and dangerous avalanche. We have been getting mixed test results in our snowpits on this weak layer, but the recent avalanche activity is all the indication we need to know the snowpack is dangerous and capable of producing large avalanches.
Yesterday: High temperatures were in the upper 20’s to low 30’s F under cloudy skies. Snow started falling in the afternoon, with 6-12″ in Girdwood, and 4-6″ accumulating in Turnagain Pass and Summit Lake overnight. Easterly winds were blowing 10-25 mph, gusting 40-45 mph, with the strongest winds starting around 8 p.m. last night. Rain made it as high as 900-1000′.
Today: The system is passing this morning, and skies are expected to clear during the day. Winds are already calming down and are expected to stay around 5-10 mph, switching westerly during the day. We might see a trace of precip this morning. High temperatures are expected in the mid 20’s to low 30’s F during the day, with lows dropping back down to the low 20’s overnight. We might see some lingering low level clouds before things clear up later in the day.
Tomorrow: It is looking like another day of quiet weather is on tap for tomorrow, with light westerly winds at 5-10 mph and mostly clear skies. High temperatures will be in the 20’s F, and no precipitation is expected.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||32||7||0.4||97|
|Summit Lake (1400′)||30||6||0.4||48|
|Alyeska Mid (1700′)||31||11||1.1||N/A|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||SE||15||32|
|05/11/22||Turnagain||Avalanche: Cornbiscuit and Magnum west faces||CNFAIC Staff Forecaster|
|05/07/22||Turnagain||Observation: Granddaddy||Kit Barton|
|04/29/22||Turnagain||Observation: Sunburst wx station||AS/ MM/ AM/ NH|
|04/28/22||Turnagain||Observation: More Turnagain Pass/Summit Lake wet slab activity||Alex Marienthal|
|04/27/22||Turnagain||Observation: Magnum||Sykes / Buttrick Forecaster|
|04/27/22||Turnagain||Observation: Girdwood/Summit/Turnagain Road obs||A S|
|04/24/22||Turnagain||Avalanche: Seattle Ridge – large glide avalanche on Repeat Offender path||CNFAIC Staff Forecaster|
|04/24/22||Turnagain||Avalanche: Seattle Ridge uptrack||Martin Schmidt|
|04/24/22||Turnagain||Observation: Pastoral||Jason Konigsberg|
|04/24/22||Turnagain||Observation: Sunburst||Lance breeding|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.