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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Tuesday, March 31st 2015
Created: Mar 31st 6:02 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
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The Bottom Line

The avalanche danger is LOW at all elevations this morning and may rise to MODERATE above 2,000' with daytime warming and sunshine. Wet loose avalanches and cornice falls, both occurring naturally and human triggered will be the main concerns if this afternoon turns sunny. Otherwise, dry sluffs should be expected on steep slopes above 2,500' that escape warming.


Primary Concern

After five days of warm stormy weather deposited several feet of good ol' Chugach Toothpaste at the upper elevations, we should see a break in cloud cover today. If this is the case, travel to the high elevations will be possible and with long days, long tours - winter is not over yet for some! We saw very little natural avalanche activity through this storm cycle. With the 'sticky' nature of the snow along with a lack of known persistent weak layers, the new snow is showing signs of stabilizing quickly. The human triggered avalanche activity that did occur was within the storm snow and relatively small.

All that said, it is springtime and that time of year where sunshine and daytime warming can be the main player for de-stabilizing the snowpack. Today's concerns:

WET LOOSE AVALANCHES:
Steep slopes with a Southerly tilt, or lower elevations, in areas where the sun shines will have wet or damp loose snow avalanche potential. Expect these to occur naturally as well as be human triggered. Keep in mind, a wet or damp sluff can entrain a significant amount of snow in steep sustained terrain.

DRY LOOSE AVALANCHES:
Dry snow exists above 2,500' and dry sluffs should be expected on shady Northerly slopes as well as Southerlies that have not yet been affected by the sun. 

DRY SLAB AVALANCHES?:
All signs point to good bonding between the storm snow and the old underlying surfaces from last week. The one exception is upper elevation Northerly slopes. These areas may harbor faceted snow under several feet of storm snow and allow for the possibility of triggering a large slab avalanche. If you are headed to high elevation shady zones, above 3,500' generally speaking, this is something to keep in mind and watch for.


Secondary Concern

Cornices deserve a lot of respect right now. They have grown substantially during the past week and though some of these have fallen on their own, many are looming. Warm temperatures and solar gain can increase the likelihood for failure. Minimizing time spend underneath them as well as giving them a wide berth on ridgelines is extremely important.

Photo below: Natural cornice failure on the West Face of Pyramid - likely occurring Sunday 3/29. Note the storm slab avalanche most likely triggered by the falling cornice. 


Mountain Weather

It was another springtime day in the backcountry yesterday with temperatures warming at 2,000' to the upper 30's F. Cloud cover broke just enough for some visibility, yet it was in and out before clearing up in the evening. Ridgetop winds were in the 5-10mph range from the East before decreasing and switching to the North overnight.

Today instability showers will be over our area as we are in a break between storms. We may see up to 2" of snow and light rain below 1,000' in some areas and sunshine in others. Ridgetop winds will remain light from the North around 5-10mph and temperatures mild, upper 30's F at 1,000' and mid 20's at 4,000'.

Wednesday night and into Thursday we will see one more weak low-pressure system move through before high pressure builds for the weekend. It could be a nice weekend for a supertour.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33   0 59 
Summit Lake (1400') 32   0 10 
Alyeska Mid (1700') 34  trace   0.02 36

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  NE 22 
Seattle Ridge(2400') 28   n/a 23 

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 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: OpenPlacer remains open but SKOOKUM DRAINAGE will close to motorized use on April 1st.
Skookum Drainage: OpenSKOOKUM DRAINAGE CLOSES TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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.


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