Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Friday, January 28th 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 avalanche hazard remains in the MODERATE range. Natural avalanches are unlikely. Human triggered avalanches are possible in specific terrain features. The recent storm snow has not shown itself to be reactive to human triggers after the storm ended. I’m still concerned about deeper weak layers that received added stress from the recent storm. Likely trigger points are in steep terrain near rocks and in shallow pockets.
Our weather history tells us a lot right now. Clear and cold weather in December and January gifted us with some weak layers that aren’t going away. Snow pits are finding all the ingredients that put us on guard: crusts, facets, buried surface hoar, and recent new snow. It’s not a terrible structure, but it isn’t great either. We expected more avalanche activity from the last storm, but only got small to medium size avalanches primarily confined to layers within the storm snow.
We’re getting far enough out from the last storm, which ended on the 25th, for people to start getting comfortable. My own feeling is caution is still warranted. In complex steep terrain you might be unlucky enough to find that trigger point, which would take you places you don’t want to go.
The most recent known human triggered avalanche was near Lost Lake on Monday. It involved a shallow full burial with a partner rescue and no injuries. This happened during the storm when triggering an avalanche is most likely.
Two concerns right now include the new snow/old snow interface and the old weak layers of buried surface hoar and facets. The mid January clear and cold spell produced large surface hoar down low (expect whoomphing in the trees) but limited growth near the ridges. We found one mid storm avalanche yesterday on the South face of Sunburst that ran on the new/old interface. This avalanche ran on an early January bed surface and is difficult to correlate into CNFAIC Staff areas. The distribution of the recent surface hoar could make mid slope and lower elevation steep slopes more dangerous than alpine terrain (remember the Grandview fatalities from last year). Old weak layers are showing failures in column tests, but nothing easy and nothing clean has been noted since the recent storm.
Encyclopedia of avalanche terms.
The recent storm ended more than 48 hours ago. There were many small natural avalanches that occurred during the storm in Turnagain pass. Yesterday was partly cloudy with light wind. We found a very thin surface crust yesterday that extended from the road to at least 3500 feet. It seemed to be some kind of local riming/graupel event that caused it. It didn’t affect skiing but you could hear it and feel it. Small surface hoar was also seen on the surface that grew as you gained elevation. Mostly cloudy skies are expected today. Chance of snow increases through the weekend.
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 28 2011
…STRONG WIND SATURDAY MORNING THROUGH SUNDAY AFTERNOON THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM…
.TODAY…MOSTLY CLOUDY. HIGHS IN THE LOWER 20S TO MID 30S. VARIABLE
WIND 10 MPH EXCEPT EAST 10 TO 20 MPH THROUGH PORTAGE VALLEY AND
.TONIGHT…MOSTLY CLOUDY. SNOW LIKELY SOUTH OF MOOSE PASS AND A
CHANCE OF SNOW ELSEWHERE. LOWS IN THE 20S. EAST WIND 10 TO 20 MPH
EXCEPT EAST 20 TO 35 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.SATURDAY…CLOUDY. SNOW SOUTH OF MOOSE PASS AND A CHANCE OF SNOW
ELSEWHERE. HIGHS IN THE LOWER 20S TO MID 30S. EAST WIND 10 TO 25 MPH
EXCEPT EAST 30 TO 45 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.SATURDAY NIGHT…SNOW LIKELY. LOWS IN THE LOWER 20S TO MID 30S.
EAST WIND 20 TO 30 MPH EXCEPT EAST 40 TO 55 MPH THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM.
.SUNDAY…SNOW LIKELY IN THE MORNING…THEN SNOW AND RAIN LIKELY
IN THE AFTERNOON. HIGHS IN THE LOWER 30S TO LOWER 40S. EAST WIND
20 TO 35 MPH EXCEPT EAST 40 TO 55 MPH THROUGH PORTAGE VALLEY AND
.SUNDAY NIGHT…CLOUDY WITH A CHANCE OF SNOW. LOWS IN THE 20S.
.MONDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW AND RAIN. HIGHS IN
.MONDAY NIGHT THROUGH WEDNESDAY NIGHT…MOSTLY CLOUDY WITH A
CHANCE OF SNOW. LOWS 25 TO 35. HIGHS IN THE 30S.
.THURSDAY…MOSTLY CLOUDY. HIGHS 25 TO 35.
TEMPERATURE / PRECIPITATION
SEWARD 31 27 36 / 0 70 80
GIRDWOOD 29 19 23 / 0 30 40
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature in the high teens to 20. Light wind from the east.
-2600′ Seattle Ridge Wx Station-
Temperature in the low 20s. Wind in the teens gusting to the mid 20s from the SE.
-1800′ Center Ridge Wx Station-
Temperature in the mid 20s. No new snow recorded. 2 inches settlement since early yesterday.