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Issued
Wed, April 13th, 2022 - 7:00AM
Expires
Thu, April 14th, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger remains LOW on all aspects and elevations. Even though it’s unlikely a person will trigger an avalanche, there are still some key hazards to look for. Limit any exposure under glide cracks, these have been releasing into avalanches over the past 3 days. Continue to give cornices a very wide berth; they are looming large and can be extremely dangerous. Watch for small slabs lingering in the high elevation shady terrain that could still be triggered. Lastly, small wet sluffs may be seen and/or triggered on hot southerly aspects late in the day.

Special Announcements
  • AKDOT&PF:  There will be intermittent traffic delays Wednesday April 13th south of Girdwood, from mileposts 88 to 83 on the Seward Highway near Peterson Creek, for Avalanche Hazard Reduction work. Motorists should expect delays between 10:00 AM and 12:00 Noon. Updates will be posted at 511.alaska.gov.
  • End of Season Operations:  This will be the final week of 7 day/wk forecasts. Beginning Monday, April 18, we will only be issuing forecasts on Tuesday, Thursday, Saturday and Sunday. The final forecast will be on Saturday April 30th.
Wed, April 13th, 2022
Alpine
Above 2,500'
1 - Low
Avalanche risk
Treeline
1,000'-2,500'
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
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.
Recent Avalanches

Seattle Ridge:  There were a few more glide avalanches noted on the SE face of Seattle Ridge yesterday. Additionally, a few have been popping out in the back of Eddie’s ridge and Wolverine on SW aspects. If you see one of these that seems new, or you witness one release, please let us know!

 

Glide avalanche seen from Cornbiscuit yesterday. This slide is on the east side of peak 4940 and is roughly across from the Bertha Ck campground on the south end of Turnagain Pass. Thank you Dan Powers for the photo, taken 4.12.22.

Avalanche Problem 1
  • Normal Caution
    Normal Caution
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

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
More info at Avalanche.org

The brilliant stretch of sunny skies and nice weather will continue again today. With only light and variable ridgetop winds expected, the only weather component that could contribute to avalanche potential will be the strength of the afternoon sun. So far, the spring temperatures have been chilly enough, and the overnight re-freeze hard enough, that the sun has only been able to soften the southerly aspects. This is opposed to melting them to the point our boot-tops sink into wet sloppy snow and wet loose avalanches start occurring. When this will happen is something to watch for as the spring progresses. Otherwise, there are a few additional ‘Normal Caution’ avalanche concerns. These are glide avalanches, cornice falls, and small slabs.

Glide avalanches are a wild thing, literally. They are not triggered by people, yet can avalanche at any time of the day. They take the whole snowpack so even a small glide avalanche can be very destructive to a person. Several have released on Seattle Ridge lately and we can expect them to keep popping out until the snow is gone. It’s imperative we do not accidentally get run over by a glide avalanche – be aware of what is around you and limit any exposure under glide cracks. These cracks are littered about and can sometimes be hard to see.

For those headed to the high elevation terrain, triggering a large cornice fall is a very real possibility. The last cornice fall we know of was the near miss on Big League in the Girdwood area. Not only do we need to give them extra space along ridgelines, it’s prudent to limit exposure under them. Triggering a small slab in steep northerly terrain is also possible in just the right spot. As always, keep an eye out for wind loaded looking areas, cracking in the snow around you, and hollow feeling snow. Even a small slab can have grave consequences if a person gets knocked off their feet in steep rocky terrain.

Maintaining safe travel protocols at all times, including these LOW danger days, will only stack the odds in our favor if someone is to get caught by surprise in an unlikely avalanche. Only expose one person at a time to steep terrain, plan your line carefully with escape routes in mind, keep an eye on your partners from safe spots. It’s good to remember that the winter mountains can have some curve balls, we need to be ready.

 

Small glide avalanche that ran next to tracks on Seattle Ridge. The debris from the glide was able to pull out a small slab on its way down the slope. This glide was believed to have released sometime Sunday night or early Monday. Photo taken on Monday, 4.11.22.

Weather
Wed, April 13th, 2022

Yesterday:  Sunny skies were over the region yet again yesterday. Ridgetop winds were light, 5-10mph, from the south and east. Temperatures rose to the mid 40’sF in the parking lots and up to the mid 30’sF along ridgelines.

Today:  Mostly sunny skies will prevail again today. There could be a few high clouds stream overhead. Ridgetop winds are forecast to be light and variable. Temperatures have dropped into the teens and 20’sF overnight in valley bottoms and should climb back to the mid 40’sF by this afternoon. Ridgetop temperatures are remaining in the 25-30F range.

Tomorrow:  One more mostly clear sky day is expected tomorrow with light winds. On Friday, clouds look to head in, although no measurable precipitation is expected. It is looking like we could get back to partly sunny skies for the weekend. Stay tuned as we all are enjoying the high-pressure period!

PRECIPITATION 24-hour data (6am – 6am)

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 37 0 0 111
Summit Lake (1400′) 38 0 0 39
Alyeska Mid (1700′) 36 0 0 N/A

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 29 W 6 15
Seattle Ridge (2400′) 30 SE 5 10
Observations
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03/27/24 Turnagain Observation: Tincan Trees
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03/20/24 Turnagain Avalanche: Seattle Creek Drainage
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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.