Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Friday, January 14th 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. It’s on the high end of MODERATE, but still below CONSIDERABLE according to their definitions. Human triggered avalanches are possible. If you know where to find avalanches I think you could make them happen. If you have no idea where to find avalanches it’s possible that you’d blunder into a bad situation.
We finally got over to the motorized side of Turnagain pass yesterday (better late than never), and the carnage after the last storm was impressive indeed. The West facing bowls seemed to catch the wind perfectly to load the slopes with deep wind drifts. We dug around the skier triggered avalanche in Warmup Bowl and confirmed the initial weak layer was buried surface hoar a few inches above the Thanksgiving Rain Crust. AnCNFAIC Staff impressive detail was the avalanche in Widowmaker, which broke back into a slope angle of 19 degrees. See photo. The convex roll quickly steepened lower down, but would have looked fairly benign at the high point before it slid.
Careful route finding and terrain management are key points to stay safe in the backcountry right now. The recent new snow is getting stronger over time as it settles and bonding forms between the grains. Avalanches are slowly becoming less likely to trigger (until we get new snow). Be aware of shallow areas in the snowpack where an avalanche is most likely to be triggered.
I’ve heard several comments recently from people talking about how they weren’t traveling on “steep” slopes. I think a lot of skiers lose their internal angle calibration without frequent practice. Remember the prime avalanche angle is generally 38 degrees, which we’ve found to be accurate with the recent buried surface hoar events. 38 degrees is deceptively low angle for many people. Right now is a great time to measure a few slope angles and remember this cardinal rule of avalanche terrain. With persistent collapsible weak layers like we have now it’s possible to trigger avalanches on much lower angle terrain. For example: the remotely triggered avalanches and the 19 degree angle of Widowmaker.
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.
Encyclopedia of avalanche terms.
Clear weather is persisting. Temperatures are a little colder than yesterday, around 0 degrees in valley floors, 5-10 degrees at the ridge tops. Wind has been light to moderate with gusts between 25 and 43 depending on location. The forecast is calling for more of the same through the weekend. First chance of a pattern change and new precipitation is 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 FRI JAN 14 2011
.TODAY…MOSTLY SUNNY. HIGHS 5 BELOW TO 10 ABOVE INLAND AND
IN THE TEENS TO LOWER 20S ALONG THE COAST. VARIABLE WIND 10 MPH
EXCEPT NORTH 15 TO 30 MPH NEAR SEWARD. WESTERLY GUSTS TO 30 MPH
DEVELOPING NEAR WHITTIER IN THE AFTERNOON.
.TONIGHT…CLEAR. LOWS ZERO TO 20 BELOW INLAND AND 10 TO 15
ABOVE ALONG THE COAST. VARIABLE WIND TO 10 MPH EXCEPT NORTH
WIND 15 TO 30 MPH NEAR SEWARD. WESTERLY GUSTS TO 30 MPH NEAR
WHITTIER IN THE EVENING.
.SATURDAY…MOSTLY SUNNY. HIGHS 10 BELOW TO 5 ABOVE EXCEPT
AROUND 15 ALONG THE COAST. VARIABLE WIND TO 10 MPH EXCEPT
NORTH WIND 15 TO 25 MPH NEAR SEWARD.
.SATURDAY NIGHT…CLEAR. LOWS ZERO TO 15 BELOW EXCEPT AROUND
10 ABOVE ALONG THE COAST. NORTH TO WEST WIND TO 15 MPH.
GUSTS TO 35 MPH NEAR WHITTIER.
.SUNDAY…SUNNY. HIGHS 10 BELOW TO 5 ABOVE EXCEPT AROUND 15
ALONG THE COAST. NORTH TO WEST WIND TO 15 MPH. GUSTS TO 35 MPH
.SUNDAY NIGHT…CLEAR. LOWS 5 BELOW TO 5 ABOVE.
.MARTIN LUTHER KING JR DAY THROUGH TUESDAY…PARTLY CLOUDY.
HIGHS 5 TO 15 ABOVE. LOWS 5 BELOW TO 5 ABOVE.
.TUESDAY NIGHT…PARTLY CLOUDY. LOWS ZERO TO 10 ABOVE.
.WEDNESDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW SHOWERS.
HIGHS IN THE TEENS.
.WEDNESDAY NIGHT AND THURSDAY…MOSTLY CLOUDY WITH A CHANCE
OF SNOW. LOWS 5 TO 15 ABOVE. HIGHS IN THE TEENS.
TEMPERATURE / PRECIPITATION
SEWARD 20 10 15 / 0 0 0
GIRDWOOD 10 -2 6 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperatures in the mid single digits. Light wind from the East.
-2600′ Seattle Ridge Wx Station-
Current temperature 8. Wind in the mid teens from the SE.
-1800′ Center Ridge Wx Station-
Temperature 7 degrees. No new snow in the past week.