CNFAIC LogoCNFAIC Logo
Turnagain Area Avalanche Advisory
Saturday, February 13th 2010 6:59 am by CNFAIC Staff
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
Previous ForecastNext Forecast
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, February 13th at 7 am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm Area with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

ANNOUNCEMENTS
We will be at the Iron Dog Safety Expo today. It runs from 10-4pm at the Denaina Center. If your not riding today come see us.

WEATHER ROUNDUP
We got a little more rain and snow out of yesterday's weather than expected. Alyeska and Portage got more rain and snow than did Turnagain Pass. Alyeska received 1.06 inches of water (12 inches of snow)and the Pass got .7(4-6 inches of snow). Even within Turnagain Pass, snow depth varied greatly. 1000 foot snow board depth readings yesterday where: Eddies-6", Motorized lot-8", Sunburst-2", and Johnson - trace. Temps are cooling off this morning and the freeze line has dipped close to sea level. Winds are light with moderate to strong gusts out of the east and southeast in the alpine.

Cloudy skies but no precipitation forecasted for today. Rain and snow will resume tonight and Sunday. The radars show limited precipitation and the satellite shows scattered cloud cover. I checked the jet stream models this morning. By Thursday we could be looking at a very south to north flow. This kind of jet brings very wet, very warm air from a long Pacific fetch.


AVALANCHE DISCUSSION
Today's avalanche hazard will remain MODERATE with pockets of CONSIDERABLE. This means that natural avalanches are unlikely, human triggered avalanches are possible. By avalanche hazard definition today is in between Moderate and Considerable. Today human triggered avalanches are certainly possible (moderate), I think they're more likely than possible (considerable). Either way today is anCNFAIC Staff heads up day!

Lots of good observations from yesterday to report. Widespread shooting cracks and collapsing (whoophing) in the snowpack. A large natural avalanche occured on the face of Petes North. CNFAIC Staff smaller ones also observed in that area. Intentional small skier triggered avalanche on Tincan. Large artilary triggered avalanches observed between Girdwood and Portage.

All this avalanche activity is failing on a layer of buried surface hoar that is located 2-3 ft. deep. This is not the rain crust from early January (that's 4-5 ft deep and could still be triggered with a large enough load). This buried surface hoar is much more reactive and needs to be respected. This type of weak layer is the one responsible for many avalanche fatalities. The shooting cracks and collapsing snowpack indicates energy in the surface slab and that a failure is occuring. If the slope angle is steep enough there will be an avalanche. I don't think we will see any natural avalanche activity today, but human triggered avalanches are likely. Areas with an increased chance of triggering an avalanche today include: slopes steeper than 30 degrees, steep convex rollovers, and wind loaded ridges. The slab will be 1-3 feet thick. Part of my concern today stems from a test that Jon and Tim did yesterday at 1700 ft on Tincan. An extended column test failed very clean (Q1-2) with full propagation, down 3.5 ft. They also ski triggered a small avalanche at 2200 ft that failed 1.5 feet deep (CTM 14/16 Q2). The natural avalanche and observations from Petes North also point to the same weak layer. BURIED SURFACE HOAR! Careful route finding and slope angle selection will be key today. Have an exit plan in mind and stay away from terrain traps. Practice good backcountry travel rituals and you should have a great day in the mountains.


WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS
500 AM AKST SAT FEB 13 2010


.TODAY...MOSTLY CLOUDY. PATCHY MORNING FOG. HIGHS IN THE MID 30S TO
LOWER 40S. VARIABLE WIND TO 15 MPH.
.TONIGHT...RAIN AND SNOW DEVELOPING AFTER MIDNIGHT. SNOW
ACCUMULATION UP TO 2 INCHES THROUGH TURNAGAIN PASS. LOWS IN THE MID
20S TO MID 30S. NORTH TO EAST WIND 10 TO 20 MPH. THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM...VARIABLE WIND 10 MPH BECOMING EAST 15 TO
30 MPH AFTER MIDNIGHT.
.SUNDAY...RAIN. HIGHS IN THE MID 30S TO LOWER 40S. NORTH TO EAST
WIND 10 TO 25 MPH EXCEPT EAST 25 TO 40 MPH THROUGH PORTAGE VALLEY
AND TURNAGAIN ARM.
.SUNDAY NIGHT...RAIN AND SNOW SHOWERS. LOWS IN THE 30S. EAST WIND 15
TO 35 MPH EXCEPT EAST 35 TO 55 MPH THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM.
.PRESIDENTS DAY...RAIN AND SNOW SHOWERS. HIGHS IN THE MID 30S TO
LOWER 40S. SOUTHEAST WIND 15 TO 30 MPH EXCEPT EAST 30 TO 45 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.MONDAY NIGHT...NUMEROUS RAIN AND SNOW SHOWERS. LOWS IN THE 30S.

TEMPERATURE / PRECIPITATION

SEWARD 38 32 41 / 0 90 80
GIRDWOOD 37 29 37 / 0 60 70




Thanks for checking todays avalanche advisory. The next one will be posted tomorrow Sunday, February 14th.

 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: 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.
FCNFAIC