Turnagain Pass

Good morning backcountry travelers this is Jon Gellings with the Chugach National Forest Avalanche Information Center on Thursday, December 9th 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).

ANNOUNCMENTS

This weekend, December 11-12, there will be an Interagency Avalanche Rescue Training taking place at Turnagain Pass. Alaska Mountain Rescue Group, Alaska Search and Rescue Dogs, Alaska State Troopers, Nordic Ski Patrol, and US Forest Service will be some of the agencies participating in this two day event. There will be scenarios on both the motorized and non-motorized sides of Turnagain Pass. The parking lot on the eastern side of the Seward Highway will still be open to the public, but will also be the location for the staging area for this training exercise. There will be some helicopter use in the area for the purpose of this training event. If you have any comments or concerns, please contact Matt Murphy by phone at 907-754-2349 or email at mattmurphy@fs.fed.us. Thank you for your cooperation with this important safety training.

WEATHER ROUNDUP

The clear weather which we were lucky enough to receive yesterday has unfortunately been replaced by a cloud layer. Snow has also once again made it into our forecast over the next few days. Look for temperatures to decrease into the teens and single digits by the end of the day. Winds shouldn’t increase too much, and forecasted new snow should be fairly negligible for today. The same Low pressure in the Gulf which has given us cloudy weather and small amounts of snow over the past several days is still loitering in our neck of the woods. NOAA is predicting that our weather should stay fairly similar for the next 7 to 8 days, so do not expect a large amount of new snow through that time.

AVALANCHE DISCUSSION

Today the avalanche hazard is MODERATE. Small to medium sized human-triggered avalanches

1-2 feet deep are possible on steep windloaded slopes, while Natural avalanches are unlikely. Use caution on steep, unsupported, and convex terrain near ridgetops and in crossloaded gullies.

Although no new avalanches have been observed or reported since last Saturday, the possibility still exists to trigger an avalanche in many areas of Turnagain Pass and the surrounding areas. Our biggest instability is due to a buried layer of surface hoar that formed between Thanksgiving and December 3rd. Underneath the surface hoar is 6 inches of low density faceted snow, which in turn is sitting on the dreaded Thanksgiving Rain Crust. Underneath this crust, we are seeing mixed forms of snow, including facets which are getting bigger. Failures on both the surface hoar layer and in the facets were fairly low energy (Q2-3)and showing moderate to high strength (2xCT & ECTN 12-23). The surface snow in upper elevations and steep terrain has settled into a slab due to warming, but was not propagating fractures in our pit Tuesday. Our primary concern today is mainly on any steep, windloaded slopes up high where the surface hoar and rain crust are buried under a dense slab of snow; a large avalanche could be produced in isolated areas due to this combination of instabilities.

Whumphing sounds have also been reported over the past week on Eddies, Tincan, and Center Ridge; be cautious when approaching steep slopes in these areas. Shooting cracks have not been observed since Sunday, but were breaking down to the layer of buried surface hoar. One of our observers went snowmachining on Sunday to Main Bowl, which is on the backside of Seattle Ridge, and reported no obvious signs of instability. He also watched a skier on Widowmaker Peak where the new snow only sluffed on the layer of surface hoar. This buried layer of surface hoar is tricky to find, so be aware of its potential presence if you are heading into more committing terrain today.

For those of you who travel to Johnson Pass, be aware that the snow is fairly similar to that in Turnagain Pass. We went out there yesterday, and lots of previous avalanche activity was seen, but the snow is a bit shallower. We were unable to find any buried surface hoar where we looked, but did find well-developed facets underneath the Thanksgiving Rain Crust. If you are out in this area, look at the snow you are travelling on, and be mindful that the snowpack could be quite dangerous in many spots.

Glide cracks and avalanches are not showing much activity recently, but do not forget about where you have seen them. They could be located under thin layers of snow, much like crevasses on a glacier. A person riding in the vicinity of a crack could potentially fall through a weak snow cover and into a crack, so be extra cautious on your descent.

Kevin 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 AKST THU DEC 9 2010

.TODAY…MOSTLY CLOUDY. A CHANCE OF SNOW NEAR SEWARD. HIGHS IN THE

MID TEENS TO LOWER 30S…COOLEST INLAND. NORTH WIND 20 TO 30 MPH NEAR

SEWARD. WEST WIND 15 MPH INCREASING TO 30 MPH IN THE AFTERNOON NEAR

WHITTIER. VARIABLE WINDS TO 10 MPH ELSEWHERE.

.TONIGHT…CLOUDY WITH A CHANCE OF SNOW. LOWS ZERO TO 15 ABOVE EXCEPT

IN THE MID 20S NEAR SEWARD AND WHITTIER. NORTH WIND 20 TO 30 MPH NEAR

SEWARD. WEST WIND 25 TO 35 MPH NEAR WHITTIER. VARIABLE WINDS TO 10

MPH ELSEWHERE.

.FRIDAY…SNOW. SNOW ACCUMULATIONS 2 TO 4 INCHES. HIGHS IN THE MID

20S TO LOWER 30S…COOLEST INLAND. NORTH WIND 25 TO 35 MPH NEAR

SEWARD. WEST WIND 25 TO 35 MPH NEAR WHITTIER. NORTH WIND 10 MPH

ELSEWHERE.

TEMPERATURE / PRECIPITATION

SEWARD 28 23 27 / 30 30 80

GIRDWOOD 18 13 21 / 0 30 80

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

recorded light Northeast winds yesterday averaging 5-10mph and temps ranging from 23F to 27F. The current temp is 23F with calm winds.

-2600′ Seattle Ridge Wx Station-

is still having trouble with wind data collection. It recorded temps ranging from 17F to 26F yesterday. The current temp is 21F.

-1800′ Center Ridge Wx Station-

recorded no new snow in the last 24 hours, although the snowpack data says it got 1″. Current total snow depth is 52 inches according to the site. Temps yesterday ranged from 15F to 29F. The current temp is 19F.