Good morning backcountry travelers this is Jon Gellings with the Chugach National Forest Avalanche Information Center on Tuesday, February 1st 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).
The Friends of the CNFAIC (FCNFAIC) needs your thoughts! With a new staff of forecasters and a list of previously completed goals, the program is growing and potentially heading in new directions. The FCNFAIC wants to know what you have to say about YOUR avalanche center, so please complete the following anonymous survey by February 20th. All information gathered will be discarded after that time. You do not need to answer all the questions, but the more complete the survey is, the better the data will be. This survey will be located here for a week, and will then be relocated to the bottom of the advisory for the remainder of the open period. Thank you in advance for taking it!
Click here to take survey
Today the avalanche hazard remains at CONSIDERABLE. Snow stopped falling at 1 AM at Center Ridge, bringing our storm total snowfall to 13” at 1800ft. Gale force winds have blown this snow along with some older snow into leeward areas, creating large snow pillows which will be touchy today. This, combined with several human triggered avalanches over the past several days has created a situation where avalanches have the opportunity to linger much longer than the “24hr rule of thought” allows. These are Dangerous Avalanche Conditions. Avalanches can, and will occur outside of this narrow window of time.
Visibility was hampered yesterday due to heavy clouds and precipitation. The snowline appeared to hover around 500ft while we were in Turnagain Pass yesterday, so a new crust is probably going to be affecting travel in areas such as Eddies and Petes N&S once temperatures return to freezing levels. We were looking for the possibility of naturally triggered avalanches, but came back empty handed due to poor lighting. Human triggered avalanches are more of our worry, because these are the ones that affect people’s lives. These are still likely to occur on many slopes above 30deg in open areas. The problem with this is that many approaches to the mountains in our entire region are close to this, or they have much steeper terrain looming over them. Failures could propagate uphill with this type of instability, which could in turn bury a person several feet underneath.
The best information we have about uphill propagation is from the Butch Mtn incident. I know this picture was posted up on the advisory yesterday, but it still paints a very vivid picture about our instabilities, which we determined to be the decomposing December snow. The avalanche was 300-400 feet wide, 1-3 feet deep, and dropped about 800 vertical feet.
We are able to learn a lot from this avalanche. Every steep slope is currently a suspect for skier or snowmachiners triggered avalanches. A large layer of surface hoar is buried down low up to ~1400ft. Several crusts and layers of facets, as well as pockets of surface hoar, are buried in our mid-elevation bands. Upper elevation areas have brand new heavy windslab, which fell on colder snow, facets, crusts, and potential trigger points. And, of course, the Thanksgiving Rain Crust is on most slopes up to around 8000ft, which is showing signs of increased energy and decreased strength.
And my roof just avalanched. 6:09AM
Recent pit information from groups on Eddies and on Lipps have shown high energy breaks above both the New Years Crust and above the Thanksgiving Rain Crust. AnCNFAIC Staff report of a human triggered avalanche came in from upper Girdwood Valley, which also failed on the TRC. All of this information came in before our current snow/rainstorm did, and all it did for us was push the snowpack closer to the breaking point. Looking for instabilities will help you make better decisions, even if you decide to turn around and not travel in steep terrain today.
Staying safe and healthy is our priority, and it is hopefully yours as well. This is not the time to push the envelope and try to ride some extreme terrain. Some days it is alright to, but today and days in the near future are definitely not them.
Encyclopedia of avalanche terms.
Winds are still blowing, with occasional gusts above 50mph. Temperatures are increasing a bit more, and rain is again in the forecast for this afternoon. The snowline will probably go up today. Precipitation has ceased for the time being, but 1.04” SWE is still in the forecast for the next 24hrs. Radar shows us in the relative clear for now, while satellite images show increasing clouds building toward us from the South.
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 FEB 1 2011
.TODAY…SNOW AND RAIN. SNOW ACCUMULATION 2 TO 4 INCHES AT HIGHER
ELEVATIONS. HIGHS IN THE MID 30S TO LOWER 40S. SOUTHEAST WIND 10 TO
20 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…SOUTHEAST WIND 25
TO 35 MPH DIMINISHING TO 10 TO 20 MPH IN THE AFTERNOON.
.TONIGHT…SNOW. SNOW ACCUMULATION UP TO 5 INCHES. LOWS IN THE
MID 20S TO LOWER 30S. EAST WIND 10 TO 15 MPH.
.WEDNESDAY…SNOW. SNOW ACCUMULATION UP TO 5 INCHES. HIGHS IN THE
UPPER 20S TO MID 30S. EAST WIND 10 TO 15 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 38 31 34 / 90 90 90
GIRDWOOD 38 30 36 / 90 90 90
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature 25 degrees. Wind gusting to 45 from the ENE.
-2600′ Seattle Ridge Wx Station-
Temperature 26 degrees. Wind gusting to 46 from the SE.
-1800′ Center Ridge Wx Station-
Temperature 32. 13″ new snow, 1” settlement. Total snow depth 86″.