Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Tuesday, January 18th 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 are 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 $100 gift certificate. At the end of this season all the submissions will go into a drawing for an avalanche beacon of your choice. Thanks for all the great work, and keep sending in those observations!
The avalanche danger rating remains at MODERATE today. While the likelihood of triggering an avalanche continues to decline, areas of instability still exist. Human triggered avalanches are still possible if you look hard enough. Predicting where you could trigger an avalanche is especially tricky right now, so use good travel techniques to minimize your exposure. Our persistent weak layers consist of numerous layers of buried surface hoar that formed in December and facets above and below the Thanksgiving Rain Crust. Unpredictable hard windslab over weak faceted snow also exists near ridgetops and in crossloaded terrain.
It has been 13 days since our last snowfall and 5 days since the last reported human triggered avalanche. While all signs point to a stable snowpack, folks are still finding areas of instability and backing off of skiing and riding steep slopes. The poor structure of our snowpack still demands caution…especially in steep high-consequence terrain. This past weekend several groups turned around and descended via their skin tracks after finding unstable faceted snow in higher elevation windloaded terrain. CNFAIC Staff groups found nothing alarming in their snowpit stability tests that kept them from their planned routes.
Persistent weak layers and hard windslab are difficult-to-manage hazards. Slope cuts are generally not effective with these types of instabilities because they tend to break above and around you. Plus you have to find just the right spot to trigger the whole thing…usually a hard-to-recognize shallow area in the snowpack. Storm snow and softslab instabilities, on the CNFAIC Staff hand, tend to break right under your sled, board, or skis and are more of a manageable hazard.
We might as well start talking about the GIANT surface hoar that’s been forming the last two weeks since snow is in the forecast tomorrow. One group reported sizeable surface hoar sluffs on steeper low elevation terrain where the crystals are 4 inches in size. These palm-size feathery crystals are widespread below 1500 feet elevation and get smaller in size the higher you go. At 3000 feet the crystals are a mere two millimeters in size. Regardless, if this stuff survives before it gets buried by the next snowfall, it will be a formidable weak layer.
Photo by Bob Sutherland
Encyclopedia of terms: www.fsavalanche.org/Encyclopedia.aspx
It has been 13 days since our last snowfall. Yesterday ridgetop winds averaged 5-10mph out of the east on Sunburst and 10-20mph out of the southeast on Seattle Ridge. Temps have gradually warmed up to around 10F at the higher elevations this morning but have cooled back down to the single digits at the mid and lower elevations. Ridgetop winds are light this morning at all locations. Skies are currently cloudy but are expected to clear up today from weak upper ridging. Ridgetop winds should remain in the 5-10mph range with mountain temps in the single digits. Looks like snow is in the forecast tomorrow finally!
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 TUE JAN 18 2011
.TODAY…PARTLY CLOUDY IN THE MORNING THEN BECOMING SUNNY.
HIGHS ZERO TO 10 ABOVE EXCEPT 15 TO 20 ALONG THE COAST.
VARIABLE WIND 10 MPH. NEAR SEWARD…NORTH WIND 20 TO 35 MPH
DECREASING TO 15 MPH IN THE AFTERNOON. NEAR WHITTIER…WEST
WIND 15 TO 30 MPH WITH GUSTS TO 40 MPH.
.TONIGHT…CLEAR IN THE EVENING…THEN INCREASING CLOUDS AFTER
MIDNIGHT WITH A CHANCE OF SNOW SHOWERS ALONG THE COAST. LOWS
10 BELOW TO 5 ABOVE EXCEPT 10 TO 15 ALONG THE COAST. VARIABLE
WIND TO 10 MPH.
.WEDNESDAY…SNOW. SNOW ACCUMULATION UP TO 3 INCHES. HIGHS
15 TO 30…WARMEST ALONG THE COAST. NORTH TO EAST WIND
10 TO 20 MPH EXCEPT NORTH 15 TO 30 MPH NEAR SEWARD.
TEMPERATURE / PRECIPITATION
SEWARD 18 9 28 / 0 60 90
GIRDWOOD 9 5 23 / 0 20 80
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded winds averaging 1-10mph out of the east the last 24 hours. Temps have been gradually climbing from a low of 2F yesterday morning to the current temp of 9F.
-2600′ Seattle Ridge Wx Station-
recorded winds averaging 15-20mph out of the southeast for 10 hours yesterday. Temps have been creeping up from a low of 3F yesterday morning to the current temp of 9F. Winds are currently light.
-1800′ Center Ridge Wx Station-
recorded no new snow the last 13 days. Temps increased from 2F to 12F yesterday but have cooled off again this morning to 3F.