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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Thursday, February 28th 2013
Created: Feb 28th 6:26 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
 Show the Complete North American Avalanche Danger Scale
Alaska Alpine Adventures LLC
Special Announcement

There is still space left in Sunday’s non-motorized Observer Training Day at Turnagain Pass.  This is the last scheduled Observer Training for the season.  Please see the CNFAIC Calendar for more details or contact Kevin at: kevin@chugachavalanche.org


The Bottom Line

The avalanche danger today remains CONSIDERABLE at all elevations.  Precipitation has been pulsing through our region over the last 48 hours dumping upwards of 2” of water in Turnagain Pass and 3.3” in Grandview.  This new load is likely to shed with the influence of a skier or snowmachiner today, as it has not yet had time to consolidate and gain strength.  Additionally, the persistent slab (late January facet/ crust combo) issue came to life yesterday morning in the Portage Valley when a large Class 4 natural avalanche buried the road to Whittier.  This persistent slab exists in the mid-elevations though affected run out zones are below treeline.


Primary Concern

Heavy, wet and dense snow continued to fall yesterday above 500’ adding up to several feet in areas not affected by the wind.  This snow looks to be bonding fairly well with underlying layers and will likely gain strength and settle out much more given time today.  Until this storm snow has adequate time to settle, soft storm slabs and loose snow avalanches will be likely to trigger in the lower elevations.  Above treeline where winds have been moderate from the east, slabs may prove more cohesive and subsequently larger in the 3-6’ range.  A storm slab avalanche above treeline is by no means “manageable” today given the sheer volume of snow.


Secondary Concern

Yesterday’s natural avalanche in Portage Valley that very likely released on on the late January facet/ crust combo is exactly the type of problem Turnagain pass has avoided thus far.  We have seen this layer reactive in Girdwood, Kern Creek and now Portage Valley, so why not Turnagain?  The crust is present and widespread throughout Turnagain in the 1500-3000’ range and we have a sizeable slab sitting ontop of it.  Likely it’s a weight issue and stress has not yet tipped the strength scale in the Turnagain zone.  It’s a bit of a wild card at this point but practicing safe travel protocols and not stopping in run out zones will be your best bet to avoid this issue.  It will be wise to limit your exposure to large mid-elevation paths such as the entire front side of Seattle Ridge where we know this crust exists.

Furthermore, we have very limited information from the Placer/ 20-mile zones at this point.  If you make it into these areas today or this weekend your observations and photos are greatly appreciated!

Additional concerns:

Cornices deserve a wide berth as they have been building steadily and tend to grow extra large with this warm, sticky snow we have seen lately.

If and when the sun comes out, expect wet and loose point releases on sun-affected slopes.


Mountain Weather

Yesterday was a full on storm day at Turnagain Pass.  Heavy snow fell throughout the day above 500’ in the 1-2”/ hour range during the peak of the storm.  Ridge top winds were blowing 20-40 mph from the east, dropping off overnight.  Temperatures continue to hover in the mid-30’s at sea level producing a rain/ snow mix for much of the day. 

Today we will likely squeeze out 2-3” more snow to end what has been a snowy February with measureable precipitation on 22 of 28 days this month.  Ridge top winds look to be in the moderate range from the SE decreasing throughout the day and shifting to the NW as skies clear and this system moves out.  Temperatures will hover in the low to mid 30’s at sea level, cooling off to the low 20’s at 4000’. 

The first few days of March look to be relatively benign with the sun making an appearance on Friday or Saturday.


 Kevin will issue the next advisory tomorrow morning on what is the first day of March!

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 15, 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: Open
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

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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