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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Tuesday, April 16th 2013
Created: Apr 16th 6:40 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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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The John Byrne Family
Special Announcement

From today until the end of April we will be issuing advisories on the weekends and Tuesday and Thursday (Sa,Su,Tue,Thur). Keep checking the observations page for information that comes in - during the week especially. And for those getting out, keep the reports coming! The next advisory will be on Thursday, April 18th.

Also, a reminder that Skookum drainage is closed to motorized use.


The Bottom Line

Much of the terrain around the Eastern Turnagain Arm has a LOW avalanche danger this morning. The exception are pockets of MODERATE danger on upper elevation slopes over 35 degrees for human triggered slab avalanches. The most likely places to find and trigger a slab are areas with prior wind loading at the higher elevations. Additionally, sun induced wet loose and wet slab activity is possible this afternoon on southerly aspects in the case the clouds hold back today.


Primary Concern

Though yesterday was a quiet day in the backcounty, we did get a number of late observations from Sunday. The first was a remotely triggered slab on Silvertip Peak (Easterly facing 4,900'). Two on Sunburst - Northerly facing ~3,500' and on southerly facing ~3,500' (this south facing slide is a couple days old). And the last, but most noteworthy, in the Girdwood Valley (West facing ~4,100'). Note each of these slabs reported are on each of the 4 aspects.

The image below is of the Girdwood Valley avalanche. This was in an area known as Surprise Bowl (see map in link above). Details are still emerging but it seems one party unintentionally triggered an avalanche that caught one of them and partially buried two people from another party while ascending the skin track below. Check the observations page for more reports sent in to us regarding this slide. This incident brings up many topics related to safe travel practices and etiquette when multiple groups are recreating in the same area. There have been a number of close calls regarding multiple groups around the country as well as last year's accident at Pete's North. Good habits keep us safer. And that is why even when a slope is littered with tracks and all seems well that we still play one at a time, watch our partners and wait for other goups below (even well below) to pass.

 

For today - It may be spring and it may have been a week now since our last snowfall, but the cold weather and buried facets surrounding crusts are keeping slab avalanches active. Most of these are old wind slabs that are sitting on a crust with a thin layer of weak snow sandwiched between. That said, we have a persistent slab concern littered about at the upper elevations. On notherly aspects we are seeing smaller shallow wind slabs sitting on old faceted snow but lack the crust bed surface.

The best way to mitigate these slabs is to do quick test pits and hand pits. As well as keep a close eye out for wind loaded slopes and cracking and collapsing (whoomphing). Much of the activity we have seen is in the upper 18" of the pack. It doesn't take long to poke in that far. Also, traveling one at time and always having an exit route planned if the slope releases is key.


Secondary Concern

Sluffing in the steeper terrain on shaded aspects should again be expected today. As for the southerly aspects, including many east and westerly slopes, the sun did a number yesterday. Many of these became damp and have refrozen overnight. With today's daytime heating, pay attention to any softening of surface crusts. In this case, watch for wet loose and shallow wet slabs to become a concern. We are expecting some cloud cover later in the day which could keep surface warming limited.


Additional Concern

Cornices. Don't forget to steer well clear of these monsters. They have been baking in the sun each day and are due to come tumbling down any time.

Bears. It seems the bears are waking up. A recently opened den was seen in upper Lyon Creek yesterday, area just north of Pastoral Peak.


Mountain Weather

Yesterday was another clear and pleasant day. Winds stayed light and variable and temperatures rose to the mid 20'sF on the ridges and upper 30'sF at 1,000'. The last measurable snowfall was on April 9th. Overnight, skies have remained clear and temperatures have dropped to the mid teens in most areas with the usual cold pools (i.e., Summit Lake and Portage) in the single digits. Winds have remained light and variable.

Today, our clear skies may be replaced with clouds in the afternoon and maybe even a flurry as a weak low pressure system tries to move in from the Gulf. Winds are forecast to remain light from a northeast direction (5mph on ridgetops). Temperatures look to rise to the 20'sF on the ridgelines and mid 30'sF at 1,000'.

Our dry spell looks to continue for the remainder of the week.


The next advisory will be issued Thursday morning, April 18th.

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: Dec 08, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedRain and snow have fallen in Turnagain Pass this week, but not enough to open for snowmachining. Continue to check back to this site for updates.
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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