CNFAIC LogoCNFAIC Logo
Turnagain Area Avalanche Advisory
Tuesday, January 19th 2010 7:07 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 Matt Murphy with the Chugach National Forest Avalanche Information Center on Tuesday January 19th 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
There are still spots available for this weekend's snowmachine avalanche workshop in Turnagain Pass. Sign up at the Alaska Avalanche School (alaskaavalanche.com) or call(907)345-0878. They will cover rescue procedures and snow assessments with some class room and lots of field work.


WEATHER ROUNDUP
Hindcast (Last 24 hours)

3800 -Sunburst Wx Station-
Temps ranged between 20-22 degrees F with light average winds 4-14 mph out of the E with a strong max gust of 25mph
Current temp 21 (1 degree colder than yesterday)

2400-Seattle Ridge Wx Station-
Winds have been calm to moderate averaging 0-18 mph out of the SE with a strong max gust of 27mph

1800-Center Ridge Wx Station-
Temps have ranged bewteen 20-30 degrees F with zero new precip and 2 inches of settlement for a total snowpack depth of 67 inches
Current temp 22 (6 degrees colder than yesterday)

Nowcast

Temps are about the same this morning from valley floors to ridgetops in the 20s. The temps at the weather stations on valley floors below 1800 range between 22-25 (thats 6-13 degrees F colder compared to yesterday). Ridgetop temps have stayed steady since yesterday ranging between 21-25 degrees F this morning. The RH is drying out up high but staying around 90% on valley floors up to 1800. Winds are currently picking up slightly on the ridgetops with some strong gusts as high as 27mph, but average wind speeds are still light. Both the Middleton and Kenai radars shows scattered light to moderate precip moving W toward the southern Kenai Mountains.

Forecast

WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS
500 AM AKST TUE JAN 19 2010
.TODAY...MOSTLY CLOUDY WITH A CHANCE OF SNOW. PATCHY FOG. HIGHS IN
THE UPPER 20S TO MID 30S. VARIABLE WINDS 10 MPH EXCEPT EAST WIND 15
MPH ALONG TURNAGAIN ARM AND NORTH WIND 15 TO 30 MPH NEAR SEWARD.
.TONIGHT...SNOW LIKELY. SNOW ACCUMULATION UP TO 4 INCHES. LOWS IN THE
LOWER 20S TO LOWER 30S. COLDEST THROUGH MOOSE PASS. EAST WIND 10 TO
20 MPH EXCEPT NORTH WIND 10 TO 20 MPH NEAR SEWARD.
.WEDNESDAY...MOSTLY CLOUDY WITH A CHANCE OF SNOW. PATCHY FOG.
HIGHS IN THE UPPER 20S TO MID 30S. LIGHT WINDS EXCEPT NORTH WIND 10
TO 20 MPH NEAR SEWARD.

Temperature / Precipitation

SEWARD 34 27 34 / 30 60 40
GIRDWOOD 36 26 30 / 30 60 30


Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass
Sea-level: GFS shows 0.25 inches of water forecasted today
3000: temps forecasted between 23 and 32 degrees F with winds 5-15 mph
6000: temps forecasted between 14 and 23 degrees F with winds 20-30 mph

AVALANCHE DISCUSSION
Todays weather should not contribute to the avalanche danger today at Turnagain Pass.

The main avalanche concern today is that slippery rain crust underneath the 1.5-2.5 feet of newer snow especially between 2000-3000. This slippery rain crust formed on Thursday Jan 7 and is widespread on all aspects from Girdwood to Summit Lake.

Over the past week, our pit data/observations from both sides of the highway at Turnagain Pass from Magnum, Sunburst, Repeat Offender, Warm Up Bowl, and Tincan have found some variability in this crust. We have found crust sandwiches, single crusts, thin breakable crust, thick bombproof crusts, and some really rotten facets underneath the crusts in some spots. Elevation is a factor in this variability, but one thing remains constant with all of the data. Simply put, the snowpack has a poor structure right now of new snow on top of a slippery bed surface. On the CNFAIC Staff hand, stability tests have been showing moderate to hard failures with fair to good stability in test pits on the new snow/crust interface. AnCNFAIC Staff piece of the puzzle is that the new snow was still reactive to human triggers yesterday 1/18/2010 (see photo gallery). People triggered class 1 to small class 2 avalanches in Girdwood Valley, Tincan, and on the motorized side. These avalanches were about 50 wide and did not run very far but they could be big enough to bury, injure, or kill a person if they happened on bigger terrain. Plus, we felt some collapsing on Sunburst yesterday, and anCNFAIC Staff group reported a collapse with a shooting crack at about 2600. Upon investigation, it appears that the collapse occurred on the rotten facets underneath the crust.

Its always better to use actual data to make decisions in the backcountry, but sometimes you have to listen to your gut and apply that to your decision making process. For whatever it is worth, I personally dont completely trust this snowpack right now for big terrain. Since it was still showing active signs of instability as of yesterday 1/18/2010, I am going to wait a little longer before getting out into bigger terrain. I think it will be wise to keep slope angles less than 38 degrees and stay away from unsupported snow fields above cliffs. The avalanche danger is decreasing today to MODERATE, but remember that the definition of MODERATE allows for the possibility of large avalanches in isolated areas. This is not a good time to go big in the backcountry.

A wild card right now are the glide cracks. One of these crevasse like features avalanched on Jan 4th for no obvious or apparent reason (see photo gallery). Glide cracks are like cornices in that they are very difficult to predict. We have not seen or had any reports of any more glide crack failures since Jan 4th, but it would still be wise to avoid traveling on, near, or underneath the path of any glide cracks.

Always remember that safe backcountry travel requires training and experience. You control your own risk by choosing where, when, and how you travel.

Thanks for checking todays avalanche advisory. The next one will be posted tomorrow Wednesday January 20th.

 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
© 2019 Chugach National Forest Avalanche Information Center. All rights reserved.
FCNFAIC