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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, March 10th 2013
Created: Mar 10th 6:15 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
The Bottom Line

Many areas today will have a generally LOW avalanche danger. Pockets of MODERATE danger can be found above treeline where lingering wind slabs 1-2’ thick and large cornices remain possible for a person to trigger. These areas are most pronounced on slopes approaching 40 degrees and steeper as well as in the Girdwood Valley where significantly more snow fell Thursday and Friday. If skies clear enough today, watch for sun induced wet loose avalanches on southerly aspects.


Primary Concern

Today’s shift to daylight savings time 2013 is accompanied by over 11 hours of daylight along with some variable snow surface conditions. The strong easterly winds during the end of last week’s storm did a little bit of damage in the Turnagain Pass zone. Everything from scoured surfaces to soft wind drifts up to 2’ deep to punchy wind crusts are out there. But don’t despair – there is still plenty of good settled powder in areas that escaped the brunt of the wind. Above 1,000' that is. Below 1,000', crusty melt-freeze conditions are firmly in place. It seems there was very little avalanche activity from the past storm event and mostly confined to cornice falls.

We found a few wind loaded slopes yesterday that showed signs of propagation and potential sensitivity to human triggers. Though no avalanche activity was seen or reported yesterday, these lingering slabs are a bit slow to bond and should be treated as suspect on steeper slopes – those approaching 40 degrees and steeper. As for the winds today, these are not forecast to be strong enough to move snow around. But in the case the disturbance over us intensifies and wind does increases, keep an eye out for any fresh wind drifts to form. Watching for cracking in the snow around you, along with stiffer snow over softer snow, will be your best clues for sussing out an old or new slab.

The Girdwood Valley received more than double the amount of snow at the end of last week than Turnagain Pass (28+” compared to ~12”). Hence, expect slabs in this region to be larger.

Additional Concerns:
Wet loose snow avalanches:  It’s that time of year. Watch for daytime heating, either by the sun or warm cloudy conditions, to dampen the surface snow. Roller balls are typically the first sign the surface is loosening and damp or wet sluffs become possible.


Secondary Concern

Once again, cornice falls make up one of the top two avalanche “Concerns”. These have grown to be very large in many areas. The past two storms were ideal cornice builders – characterized by mild temperatures and moderate to strong winds. Though Thursday saw 100+mph winds - too strong for good cornice growth – the majority of the snow came in after that, when wind had slackened to the 50mph range. Remember, cornices can release spontaneously just as easy as they can be triggered by a person, or several people, on ridgelines. Giving these guys a wider berth than thought necessary and steering clear of areas underneath them, especially during the heat of the day, will be wise.


Mountain Weather

Yesterday’s chance for precipitation was denied and we have had no new snow in the past 24 hours. The sun broke through the clouds off and on throughout the day and winds were light from the southeast averaging ~10mph. Temperatures have remained in the low 20’s on the ridgetops and mid 30’s at sea level.

Today, a low pressure centered over western Alaska will push to the southeast and usher clouds over our area. We can expect a chance for a trace to an inch of snow. Winds are currently light and variable and look to pick up on the ridges to the 10-15mph range from the southeast. Temperatures look to remain around 20F on the ridgelines and mid 30’s at sea level.

A ridge of high pressure is forecast to build over the Bering for the early part of this week. This should bring clear skies and mostly light northeast winds with slightly cooler temperatures.

 


 Fitz will issue the next advisory tomorrow morning, March 11th.

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 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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.


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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