CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, January 6th 2019 7:00 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
Previous ForecastNext Forecast
BROUGHT TO YOU BY
The Bottom Line

The avalanche danger remains MODERATE above 1,000'. Finding and triggering a slab avalanche 2-3’ thick is becoming less likely but still possible; most suspect areas are higher elevations that have seen prior wind effect. Second, glide cracks (brown cracks in the snow) are opening and avalanching during this cold snap. This is the time to avoid being under cracks. And as always, give cornices a wide berth, some may be teetering on the edge of breaking.

SUMMIT LAKE / JOHNSON PASS / LYNX DRAINAGE: South of Turnagain Pass, keep in mind multiple buried weak layers exist in the middle and base of the snowpack. More potential for triggering a large slab avalanches exists in this zone. 


 Show the Complete North American Avalanche Danger Scale
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

As time passes and more information is gathered, we are finding that being able to trigger a slab avalanche breaking 2-3' deep is becoming less and less likely. Although this is a good trend, we can't write this avalanche problem off just yet. The mountains have a way of humbling us and therefore, it will be prudent to keep in mind a buried layer of surface hoar may sit 2-3' below the surface. Higher elevation zones that saw prior wind effect are most concerning for finding one of these isolated pockets.

This can be a spooky situation. We can stick to lower angle slopes or if we're bent on the steep terrain, consider the consequences if part or all of the slope does release. Is there a terrain trap under us? Watch our partners and expose one person at a time. Again, the one known avalanche in this layer was on Wednesday, Jan. 2nd on Seattle Ridge, which was the day after the end of the New Year's storms. Otherwise, snowpack tests and pits have shown the layer to be either not present or generally unreactive. 

 

              

The CNFAIC crew out in the God's County area on the northern end of Seattle Ridge assessing the spatial variability in the Christmas buried surface hoar. Two pits at 1,500' showed reactivity and propagation propensity, but many others did not. 

South of Turnagain - Lynx Creek/Johnson Pass/Summit Lake zone:  A poor snowpack structure exists in these areas. The buried surface hoar mentioned above exists as well as facet/crust combinations in the bottom of the snowpack. The New Year's storm overloaded a variety of these weak layers as can be seen in photos from the avalanche activity throughout Summit LakeIf you're headed this way, the pack becomes more complex - evaluate terrain exposure and the snowpack as you travel. Remember ‘whumpfing’ and recent avalanches are obvious clues of instability.


Avalanche Problem 2

Glide Avalanches

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

The brown cracks easy to see in the Turnagain area are glide cracks. Take a good look at the photos below. The whole snowpack is slowly sliding down the mountainsides and can release into an avalanche at anytime. This is a completely unpredictable situation and one where a human does not play a role. Glide cracks are releasing now. Please don't be caught in the wrong place at the wrong time and limit/avoid exposure under any crack you see. The most recent glide avalanche we know of was on the south face of Eddies where the glide debris covered fresh ski tracks

Cracks we know about are in all the hot spots on Turnagain: Lipps, Tincan, Eddies, Lynx Creek, Johnson Pass, Sunburst, Corn Biscuit, Magnum, Seattle Ridge.

 

Glide avalanche on south face of Eddies - take a close look as the bed surface (ground) could be mistaken for rocks. The debris in this photo covered recent ski tracks - likely released sometime 1/4 or early on 1/5. Photo: Alan Abel.

 

Glide cracks and an older portion that released (avalanched) Dec. 27/28 - note the small crack opening up on the upper left of photo. These could avalanche at any moment. Photo: Trip Kinney.

 

 

Glide crack under Tincan's Hippy Bowl. These are now opening up at lower elevations. Photo: Mark Turner. 


Mountain Weather

Yesterday:  Mostly clear skies were over the region. Ridgetop winds were light from a generally west direction (5-10mph). Temperatures remain cold and inverted; minus single digits in the parking lots and the low teens F along ridgelines.

Today:  Mostly clear skies will be over the area again today. Ridgetop winds are expected to remain light, 5-10mph, from the NW. Temperatures stay cold (-10 to 0F) at the lower elevations and in valley bottoms as an inversion remains. Ridgeline temperatures are only slightly warmer at 5-10F... burrr...

Tomorrow:  Sunny skies and cold temps are on tap to remain into the week. There is a chance for some clouds and snow flurries on Tuesday. Ridgetop winds at this point look to remain light from a NW direction. 

*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 58 
Summit Lake (1400') -6 19 
Alyeska Mid (1700') 46 

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 11  16 
Seattle Ridge(2400') 12  *N/A  *N/A   *N/A  

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).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Mar 22, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
Summit Lake: Open

Subscribe to the Turnagain Area Avalanche Advisory:

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
© 2019 Chugach National Forest Avalanche Information Center. All rights reserved.
FCNFAIC