Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Thursday, January 13th 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).
We’re starting an incentive program to encourage everyone to submit snow and avalanche observations. Each quality observation will earn you one chance to win a monthly prize. At the end of this season all the submissions will go into a drawing for an avalanche beacon. Thanks for all the great work, and keep sending in those observations!
The avalanche hazard rating is MODERATE today. I think the qualifier of “dangerous MODERATE” is a better description. It’s on the high end of MODERATE, but still below CONSIDERABLE according to their definitions. You really need to read the description of this rating closely to realize what it means. Human triggered avalanches are possible.
According to the avalanche danger rating you should, “Evaluate snow and terrain carefully.” This is a tough one to do today. We know that the snow is consistently weak with an inconsistent slab on top. Terrain evaluation is what keeps you safe right now, but doing this well is difficult unless you simply stay on lower angle slopes. The most recent reported skier triggered avalanche on Twin Tip (see picture below) was triggered by a conscious and deliberate group of skiers. They were evaluating the snow and terrain to do what they could to minimize the risk to their party and try to avoid getting into dangerous terrain. I’m guessing that their safe travel technique (traveling one at a time between safe spots) is what kept them safe when they did trigger this avalanche. The take home message is that even backcountry travelers in the right mindset are finding these avalanches. Trying to outsmart these conditions can be quite difficult.
Look for the ski tracks leading into the avalanche.
Persistent slab, facets, and surface hoar are the culprits right now. We’ve investigated a number of different avalanches since the last storm, and the common thread is that they fail on multiple different weak layers. Buried surface hoar seems to be initiating the larger avalanches, then they step down to deeper layers around the Thanksgiving rain crust.
Primary concern: Persistent slab. The two most common weak layers responsible for fatal avalanches are buried surface hoar and facets, and we have both right now.
Encyclopedia of avalanche terms.
We’re back into a solid high pressure pattern. Sunny skies have dominated since the end of the last storm. Right now we’re slipping into a bit of a temperature inversion. Some of the standard cold valleys such as Portage and Summit are near 0 degrees. Temperatures at the ridge tops are in the mid teens. The wind has been blowing moderately the last couple days with gusts into the 40s. The upper ridges are showing that wind effect with a stiffer surface slab forming. The National Weather Service has no precipitation in the forecast until Wednesday.
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-
500 AM AKST THU JAN 13 2011
.TODAY…SUNNY. HIGHS ZERO TO 15 ABOVE EXCEPT LOWER 20S ALONG
THE COAST. VARIABLE WIND 10 MPH. NEAR SEWARD…NORTH WIND
10 TO 15 MPH INCREASING TO 20 TO 30 MPH IN THE AFTERNOON.
.TONIGHT…MOSTLY CLEAR. LOWS ZERO TO 10 BELOW EXCEPT 5 TO 15
ABOVE ALONG THE COAST. VARIABLE WIND TO 15 MPH EXCEPT NORTH
20 TO 35 MPH NEAR SEWARD.
.FRIDAY…PARTLY CLOUDY IN THE MORNING THEN BECOMING MOSTLY
SUNNY. HIGHS 5 BELOW TO 5 ABOVE EXCEPT 15 TO 20 ALONG THE COAST.
VARIABLE WIND 10 MPH EXCEPT NORTH 15 TO 30 MPH NEAR SEWARD.
.FRIDAY NIGHT…CLEAR. LOWS 5 BELOW TO 20 BELOW EXCEPT AROUND
10 ABOVE ALONG THE COAST. VARIABLE WIND 10 MPH EXCEPT NORTH
15 TO 30 MPH NEAR SEWARD.
.SATURDAY…MOSTLY SUNNY IN THE MORNING THEN BECOMING PARTLY
CLOUDY. HIGHS 5 BELOW TO 5 ABOVE EXCEPT AROUND 15 ALONG THE COAST.
VARIABLE WIND TO 10 MPH EXCEPT NORTH 15 TO 30 MPH NEAR SEWARD.
.SATURDAY NIGHT…PARTLY CLOUDY. LOWS ZERO TO 15 BELOW.
.SUNDAY THROUGH MARTIN LUTHER KING JR DAY…PARTLY CLOUDY.
HIGHS IN THE TEENS. LOWS ZERO TO 10 BELOW.
.MONDAY NIGHT AND TUESDAY…PARTLY CLOUDY. LOWS 5 TO 15 ABOVE.
HIGHS 15 TO 25.
.TUESDAY NIGHT…PARTLY CLOUDY. LOWS IN THE TEENS.
.WEDNESDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW SHOWERS.
HIGHS 15 TO 25.
TEMPERATURE / PRECIPITATION
SEWARD 20 11 16 / 0 0 0
GIRDWOOD 12 -2 6 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Current temperature 13 on a falling trend. Wind also dropping recently to light and variable.
-2600′ Seattle Ridge Wx Station-
Current temperature 16. Recent light wind.
-1800′ Center Ridge Wx Station-
Temperatures in the mid teens. No new snow.