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Turnagain Area Avalanche Advisory
Saturday, March 27th 2010 6:33 am by CNFAIC Staff
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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BROUGHT TO YOU BY
The Bottom Line
Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday March 27th, 2010 at 7 am. This will serve as 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).

ANNOUNCEMENTS
This week is Telepalooza week at Alyeska Resort. There are lots of great events and a fundraiser for the Friends of the Chugach National Forest Avalanche Information Center. Check Alyeska Resort's webpage or www.telepalooza.com for a detailed schedule of events.

WEATHER ROUNDUP
AnCNFAIC Staff nice day yesterday has lead us to cloud covered skies today. The leading edge of a 966mb L has already passed over our area. Temperatures and winds are currently climbing. The freeze line is forecasted to rise to 1300 ft from it's current location at sealevel. Winds are also forecasted to increase significantly today. An active weather system with multiple low pressure systems is forcasted for the next week. Snow switching to rain today with 2-5 inches of snow at higher elevations.

AVALANCHE DISCUSSION
Todays avalanche danger is MODERATE with an increasing danger trend. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully. Natural avalanches unlikely; human triggered avalanches possible.

We have multiple weak layers in the upper 3 feet of our snowpack. These layers consist of surface hoar on all aspects, and suncrusts on southerly aspects.

A couple more good snow stability tests came in yesterday indicating that our weak layers are not going away. The very dynamic nature of a spring snowpack require diligent snow analysis. Good snow stability in one couloir means nothing about the snow stability right around the corner.

Likely areas to trigger avalanches today include: steep hanging alpine snowfields near ridgetops and steep convex rollovers.

There are three main problem layers in the snowpack right now:
1. A sun crust with surface hoar on top is buried under Tuesdays new 4-6 inches of new snow. We observed surface hoar on top of this crust in multiple locations. This layer could create small human-triggered avalanches on steep slopes where wind has deposited deeper snow.
2. A sun crust that is buried 2-3 feet deep (we have observed surface hoar near this crust) We have been finding moderate to hard failures with smooth shear planes on top and underneath this crust. It might become more reactive with a heavier load on top of it, or small avalanches might step down to this layer making medium sized avalanches.
3. Multiple layers of buried surface hoar in the top 1-3 feet of snow


There is a lot of spatial variability in the snowpack right now including multiple layers of buried surface hoar and buried suncrusts in the top 3 feet of snow. At lower elevations, there is a 1 inch thick breakable crust on all aspects up to about 1500-2000 which is now buried under 4-6 inches of wet snow. Mid elevations to ridge top elevations generally have multiple buried suncrusts on southern aspects, but these crusts are very aspect-dependent and do not wrap around to CNFAIC Staff aspects. The uppermost suncrust was thin but it had surface hoar on top of it. Northern aspects at Turnagain Pass are generally thin, cold, and faceted especially in rocky areas.

Glide cracks are secondary concern today. These crevasse like features are those cracks that go all the way to the ground. One of these glide cracks avalanched a week ago on the southern aspect of Tincan to the lookers left of Tincan Proper (see photo gallery).




WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS
500 AM AKDT SAT MAR 27 2010

...STRONG WIND THIS AFTERNOON THROUGH THIS EVENING THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM...

.TODAY...RAIN AND SNOW IN THE MORNING...THEN RAIN SHOWERS IN THE
AFTERNOON. SNOW ACCUMULATION UP TO 2 INCHES...MAINLY AT HIGHER
ELEVATIONS. HIGHS AROUND 40. EAST WIND 10 TO 20 MPH INCREASING
TO 20 TO 35 MPH WITH GUSTS TO 50 MPH THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM.
.TONIGHT...RAIN SHOWERS. LOWS IN THE 30S. EAST WIND 20 TO 35 MPH
DIMINISHING TO 10 TO 25 MPH AFTER MIDNIGHT. GUSTS TO 50 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM IN THE EVENING.
.SUNDAY...RAIN SHOWERS. HIGHS IN THE LOWER TO MID 40S. EAST
WIND 10 TO 20 MPH.
.SUNDAY NIGHT...RAIN SHOWERS LIKELY AND A CHANCE OF SNOW SHOWERS.
LOWS IN THE 30S. NORTH TO EAST WIND 10 TO 15 MPH.
.MONDAY...CLOUDY WITH A CHANCE OF RAIN AND SNOW SHOWERS.
HIGHS IN THE UPPER 30S TO MID 40S. NORTH TO EAST WIND 10 TO 15 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 41 35 43 / 100 80 80
GIRDWOOD 39 36 41 / 100 80 80




WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800-Sunburst Wx Station
19 degrees F, 19 mph wind averages with gust to 32. Winds are increasing and easterly.

2600-Seattle Ridge Wx Station
23 degrees F, 14 mph wind averages with gusts to 27. Winds are increasing and southeasterly.

1800-Center Ridge Wx Station
26 degrees F, 0 new snow, 128 inches of total snowpack.

Thanks for checking todays avalanche advisory. Lisa will update this advisory tomorrow morning by 0700. Thanks and have a great day.

 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.

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 20, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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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