Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Saturday, January 29th 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
The avalanche hazard remains MODERATE. Natural avalanches are unlikely. Human triggered avalanches are possible in steeper, alpine, wind-loaded pockets. One avalanche was reported yesterday in high angle terrain in Turnagain pass. AnCNFAIC Staff concern is low elevation steeper slopes where very large surface hoar formed through January.
Yesterday we got the confirmation we’ve been waiting for. A human triggered avalanche (2 feet deep, 150 feet wide, 45 degree slope, triggered by the 3rd skier) happened yesterday in a back bowl up Bertha creek (Superbowl). The reporting group described it as being “predictable in hindsight and a solid confirmation that it’s not worth stepping onto any of the bigger lines in the pass right now.” It may have slid on the recent storm interface with the older snow. Hopefully we can confirm that today.
AnCNFAIC Staff skier triggered avalanche was reported in the Winner Creek area of the Girdwood valley. It was described as a small feature, 50 feet wide, but broke all the way to the Thanksgiving Rain Crust.
The conditions we have right now are some of the most difficult to predict. Our reports have been calling the hazard Moderate for much of December and January, but infrequent human triggered events confirm that the hazard lingers. As time passes from the most recent storm the new snow will bond and set up, becoming more stable. Unfortunately persistent weak layers are everywhere in our region. They don’t go away easily and are possible to trigger long after the most recent storms.
I’ve noticed that backcountry travelers this season have mostly been staying on mellow to average terrain because of the unstable snow structure. This has kept people safe so far. It seems that when people push out onto the steeper terrain they are finding the weaknesses. AnCNFAIC Staff aspect that makes prediction difficult is large variability of snow depth distribution caused by wind loading and a relatively shallow snowpack. Almost all of the snowpits we are seeing right now are showing ok results with medium to hard failures and poor fracture quality. The more important detail in snow pits right now is the presence of multiple significant persistent weak layers.
Two concerns right now include the new snow/old snow interface and the old weak layers of buried surface hoar and facets. See the photo page for examples of snow profiles and the widespread distribution of facets, crusts, and buried surface hoar.
The distribution of the most recent surface hoar could make lower elevation steep slopes surprisingly dangerous (remember the Grandview fatalities from last year). Most people are not traveling in this more heavily treed terrain, but it could produce some big surprises. We have several recent reports of massive sphincter clenching whoomphs in the trees. This was predictable from the presence of abnormally large surface hoar. If you find that collapse on a slope it could easily avalanche.
Encyclopedia of avalanche terms.
The most recent snowfall ended on the 25th. Calm wind has kept the snow fairly loose since then, but wind picked up last night and is expected to increase today. Starting today snow is again in the forecast. A trace is predicted today with increasing amounts tonight and tomorrow. The loose snow at the ridges was blowing yesterday afternoon and recent wind loading could aggravate the alpine instabilities.
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 SAT JAN 29 2011
…STRONG WIND SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM…
.TODAY…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. HIGHS IN THE LOW
TO MID 30S. EAST WIND 10 TO 15 MPH. THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM…SOUTHEAST WIND 15 TO 30 MPH INCREASING TO 25 TO 40
MPH IN THE AFTERNOON.
.TONIGHT…MOSTLY CLOUDY WITH A CHANCE OF SNOW. LOWS IN THE MID
20S TO LOWER 30S. EAST WIND 15 TO 25 MPH EXCEPT EAST 25 TO 40 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.SUNDAY…MOSTLY CLOUDY. A CHANCE OF SNOW IN THE MORNING…THEN A
CHANCE OF SNOW AND RAIN IN THE AFTERNOON. HIGHS IN THE LOWER TO
MID 30S. EAST WIND 15 TO 30 MPH EXCEPT EAST 30 TO 45 MPH THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM.
.SUNDAY NIGHT…SNOW AND RAIN LIKELY. LOWS IN THE MID 20S TO LOWER
30S. EAST WIND 20 TO 35 MPH EXCEPT EAST 45 TO 60 MPH THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM.
.MONDAY…SNOW AND RAIN LIKELY. HIGHS IN THE 30S. SOUTHEAST WIND 15
TO 30 MPH EXCEPT 35 TO 50 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN
.MONDAY NIGHT…SNOW AND RAIN LIKELY. LOWS 25 TO 35.
.TUESDAY…RAIN AND SNOW LIKELY. HIGHS IN THE 30S.
.TUESDAY NIGHT…SNOW AND RAIN LIKELY. LOWS 25 TO 35.
.WEDNESDAY…RAIN AND SNOW LIKELY. HIGHS IN THE 30S.
.WEDNESDAY NIGHT…CLOUDY WITH A CHANCE OF SNOW. LOWS IN THE 20S.
.THURSDAY…MOSTLY CLOUDY. HIGHS 25 TO 35.
.THURSDAY NIGHT AND FRIDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW.
LOWS IN THE 20S. HIGHS 25 TO 35.
TEMPERATURE / PRECIPITATION
SEWARD 34 29 35 / 40 40 40
GIRDWOOD 31 24 31 / 20 30 40
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperatures in the high teens. Wind in the teens gusting to the 20s from the ENE.
-2600′ Seattle Ridge Wx Station-
Temperature in the low 20s. Stronger wind at this site, steady in the 20s gusting to the 40s from the SE.
-1800′ Center Ridge Wx Station-
Temperature in the mid 20s. No new snow recorded. AnCNFAIC Staff 2 inches settlement since early yesterday.