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Turnagain Area Avalanche Advisory
Sunday, March 28th 2010 6:43 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 Lisa Portune with the Chugach National Forest Avalanche Information Center on Sunday, March 28th at 7am. 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
Today is the last day of Telepalooza 2010. Check out details at www.telepalooza.com. The uphill/downhill race starts at 9am at the daylodge plus on-going free demos, lessons, beacon park games, and a raffle at the Sitzmark. The raffle tonight has HUGE prizes with all proceeds going to the Friends of the Chugach National Forest Avalanche Center.

WEATHER ROUNDUP
15 inches of heavy wet snow fell in the last 24 hours in Turnagain Pass while 17 inches fell in Grandview, 16-24 inches in the upper elevations of the Girdwood Valley, and 3 inches in the Summit Lake area. Mountain temperatures warmed up to the low 20s to low 30s yesterday while ridgetop winds averaged 20-30mph out of the east with gusts to 44mph. The monster-sized snowflakes turned to rain at sea level late yesterday afternoon and then back to snow early this morning. Only a few inches of snow accumulated at sea level. The winds tapered off last night and are currently averaging 5-10mph out of the east. Temperatures cooled down by a few degrees last night and currently range from 21F@3800 to 25F@1800 to 32F@sealevel. A strong frontal wave moving northwest out of the gulf will bring more snow and rain today. We could see anCNFAIC Staff 2-5 inches of snow at the higher elevations and rain below 1000 feet. Easterly ridgetop winds will average 5-15mph while mountain temperatures will warm up to the mid 20s to mid 30s this afternoon.

AVALANCHE DISCUSSION
The avalanche danger has increased to CONSIDERABLE today on all slopes steeper than 35 degrees. This means that human-triggered avalanches are LIKELY on steep slopes while natural avalanches are possible. The addition of 1-2 feet of heavy wet snow, and winds strong enough to move the snow onto leeward aspects, means that dangerous avalanche conditions exist. Please remember that the majority of human-triggered avalanches occur during or within 24 hours of a storm. If by chance we see the strong springtime sun today, even for a short period of time, expect almost instant wet sluffs possibly triggering slab avalanches on steep southerly slopes.

Deb and I toured up Tincan yesterday and easily triggered new snow slabs on small convex test slopes. At 2500 feet we got long shooting cracks breaking a foot deep down to a sun crust on actively loading rollovers. Small natural avalanches were also reported late yesterday afternoon in the Girdwood Valley and Summit Lake area. The 1-2 feet of new snow fell on a layer of surface hoar that formed on all aspects up to 4000 feet this past Thursday and Friday. The new snow also buried a slick sun crust on southerly aspects and cold powdery snow on north aspects. Remotely triggered slides are a concern today where the surface hoar was buried intact standing upright, so watch the slopes above you. This feathery crystal is famous for producing long-running fractures, and its even more dangerous when it forms on a slick crust.

Of equal concern are the multiple buried weak layers in the top 2 to 4 feet of the snowpack that formed during the last few weeks. New snow avalanches triggered today could step down to these deeper layers. These weak layers include numerous sun crusts on SE-S-SW aspects, a 1-inch thick melt-freeze crust below 2000 feet on all aspects, large developed facets on shallow north aspects above 3000 feet, and 3 separate scattered layers of buried surface hoar on multiple aspects. These layers were responsible for five skier-triggered avalanches this past Thursday and Friday:

- North aspect of Granddaddy Chute (Bertha Creek drainage), 2.5 feet deep, 150-200 feet wide.
-Taylor Pass between Sunburst and Magnum, windloaded north aspect, triggered while skinning, 3400 feet elevation, 80-90 feet wide, 1.5-2 feet deep, ran 300 feet on layer of buried surface hoar.
-South face of Sunburst at highest point, triggered while skiing on convex rollover, 6-9 inch deep crown face, ran 3/4 of the way to the bottom, happened at 12:30pm.
- North face of Sunburst near the top of Elevator Shaft. The skier triggered it on his third jump turn from the top. It broke 2-3 feet deep and ran 1000 feet.
-South face of A1 in the Upper Girdwood Valley between 4000 and 5000 feet. No information reported on this slide.


I will issue the next advisory tomorrow morning at 7am. If you get out in the backcountry give us a call at 754-2369 or send us your observations using the button at the top of this page. Thanks and have a great day.

The NWS weather forecast for:
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS

500 AM AKDT SUN MAR 28 2010

.TODAY...SNOW AND RAIN. A SLIGHT CHANCE OF FREEZING RAIN IN THE
MORNING. SNOW ACCUMULATION UP TO 2 INCHES. HIGHS IN THE UPPER 30S TO
MID 40S. VARIABLE WIND 15 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN
ARM...LIGHT WINDS BECOMING EAST 15 TO 30 MPH IN THE AFTERNOON.
.TONIGHT...RAIN AND SNOW. SNOW ACCUMULATION UP TO 2 INCHES. LOWS IN
THE UPPER 20S TO MID 30S. NORTHEAST WIND 10 TO 15 MPH.
MONDAY...NUMEROUS RAIN AND SNOW SHOWERS. SNOW ACCUMULATION UP TO 1
INCH. HIGHS IN THE UPPER 30S TO MID 40S. VARIABLE WIND 15 MPH.
.MONDAY NIGHT...SNOW AND RAIN LIKELY. LOWS IN THE MID 20S TO
LOWER 30S. LIGHT WINDS.
.TUESDAY...SNOW AND RAIN LIKELY. HIGHS IN THE MID 30S TO LOWER
40S. LIGHT WINDS EXCEPT WEST 10 TO 15 MPH NEAR WHITTIER.

TEMPERATURE / PRECIPITATION

SEWARD 44 31 42 / 100 80 80
GIRDWOOD 41 28 42 / 80 70 50


WEATHER STATION SUMMARY for Turnagain Pass:
-3800 Sunburst Wx Station-
recorded moderate to strong winds yesterday averaging 20-30mph with gusts to 44mph. The current temp is 21F (2 degrees warmer than this time yesterday) with winds averaging 10mph out of the east.

-2600 Seattle Ridge Wx Station-
recorded moderate winds yesterday averaging 15-25mph with gusts to 40mph. The current temp is 25F (3 degrees warmer than this time yesterday) with winds averaging 5mph out of the east.

-1800 Center Ridge Wx Station-
recorded 15 inches of new snow and 1.2 inches of water in the last 24 hours. The current temp is 26F (1 degree warmer than this time yesterday) with a total snowpack depth of 142 inches.
 Show the Complete North American Avalanche Danger Scale
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.

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: Jan 13, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: Open
Skookum Drainage: Open
Turnagain Pass: Open
Twentymile: ClosedClosed. Forest Service is monitoring conditions.
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: 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
© 2019 Chugach National Forest Avalanche Information Center. All rights reserved.
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