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Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, April 17th 2018 4:44 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is LOW this morning and may rise to MODERATE in the afternoon. Triggering a small to large wet avalanche will be possible with daily warming on sunlit aspects or with rain at lower elevations. In the Alpine, triggering a slab avalanche 1-2’ thick remains possible above 3000’ on shaded aspects. Give cornices extra space. 

WEDNESDAY AVALANCHE OUTLOOK:
No avalanche forecast will be issued tomorrow, Wednesday April 18th. The avalanche hazard will be MODERATE. Watch for changing conditions as snow and rain fall and wind speeds increase. Pay attention to how the new snow is bonding to the melt-freeze crusts. If precipitation amounts are higher than forecast the danger may rise to CONSIDERABLE. 


 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Special Announcement

The snow is melting fast at lower elevations and the following areas have been closed to snowmachining on the Chugach National Forest: Placer, Twentymile, Snow River, Primrose, Lost Lake. Snug Harbor access to Lost Lake remains open at this time. Keep an eye on the riding status at the bottom of this page for current updates. 

Be aware some summer hiking trails like Byron Glacier trail in Portage have steep avalanche terrain above them and the potential for a natural avalanche exists later in the day on slopes getting lots of sun in the afternoon or if it rains. 

CNFAIC is transitioning to spring time hours in preparation for the end of the season. We are issuing forecasts 4 days/wk on Sat, Sun, Tue, Thur. The final forecast will be on April 28th. You can check out springtime tips on the final Summit Summary HERE. 


Avalanche Problem 1

Wet Loose

Almost Certain
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Likely
Possible
Unlikely

Chance

Historic
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Size

Today's weather is forecast to be a little bit of everything. It looks to start out sunny and then transition to rain and snow showers with increasing East winds. Crusts that formed overnight may or may not soften in the sunshine by late afternoon. If the snow does become soft (and especially if it starts to rain after) the potential for wet loose activity at lower elevations will increase. Observations over the weekend found the weakest wet snow conditions below 2500’ on very steep East to South aspects. There is more potential for wet snow to entrain a larger avalanche in this elevation band if they warm up enough. Don't let this catch you off guard if you start out in the upper elevations and the snow quickly changes as you descend. Pay attention to surface crusts as they break down and become moist. When the snow becomes wet and 'mushy' and your skis or snowmachine track start trenching into wet snow, it's time to find supportable surfaces. Even a small wet avalanche could be hard to manage especially in a terrain trap. 

Cornices: Daily warming and sunnier weather can make cornices more unstable. As always, give cornices plenty of space and limit exposure underneath them.

Recent cornice triggered slab avalanche above Skookum and old wet loose avalanches. 


Additional Concern

Persistent Slabs

Triggering a persistent slab 1-2’ deep is becoming less likely with time. Old weak snow (facets) buried within the top 2’ of the snowpack has been found in the upper elevations over the last few weeks. Northerly aspects above 3000’ with dry snow may harbor this set up. So far there have been no reports of any avalanche activity on these shaded slopes following last week's storm. However, the periphery of our forecast zone is more suspect, Crow Pass area and Johnson Pass to Summit Lake, where a thinner (weaker) snowpack remains. Before committing to steeper slopes in the upper elevations, take a moment to evaluate the terrain for consequences should a slab release.  


Mountain Weather

Yesterday was partly sunny with high clouds moving in. Temperatures were in the 30Fs and 40Fs. Winds were from the East 5-15 mph with gusts into the 20s. Overnight temperatures were in the low 30Fs to mid 20Fs. 

Today is forecast to be partly to mostly cloudy. There is chance of rain and snow showers in the late afternoon. Easterly winds will increase with gusts into the 30s and 40s. Temperatures will be in the 20Fs to low 40Fs depending on elevation. Tonight rain and snow showers are likely but not much accumulation is expected. Rain/snowline is forecast to be around 1000'.

Tomorrow the rain and snow showers continue and East winds will remain elevated. Temperatures will be in the high 20Fs to low 40Fs.The wet weather and Southeast flow continue into Thursday. There is another low moving into the Gulf this weekend, which could bring more rain to the area. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 36   0 65 
Summit Lake (1400')  30    0  23  
Alyeska Mid (1700') 35    0  60 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  25  ENE 20 
Seattle Ridge(2400')  31  ESE  10 25 

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: May 06, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20th
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: ClosedClosed as of May 7th. Happy summer, see ya when the snow flies!
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: ClosedClosed as of 4/27
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: ClosedClosed as of 4/27
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

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
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