Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Friday March 12th, 2010 at 7 am. 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).
Southeast winds remain light this morning. Temps are chilly ranging from -9 at Summit Lake to 8 at sealevel in Girdwood. Ridgetops are seeing 2 to -3 degrees F. The radar image shows scattered precip over Prince William Sound and the satellite indicated partly clear. No new snow in the last 24 hours.
Today’s danger level will stay at MODERATE due to lack of significant weather in the past 24-48 hours, time since the last major storm, and no significant weather forecasted for today.
Moderate avalanche danger means heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Natural avalanches unlikely; human triggered avalanches possible.
We received a report of a human triggered avalanche on the south aspect of Cornbiscuit yesterday afternoon. The slope had been skied 5 plus times prior to release. The avalanche was triggered when a pair of skinners pushed the skin track farther up the ridge than previous. The avalanche was triggered in a shallower snowpack near some rocks and propagated 300-500 ft across. It broke 1-3 ft deep and ran full track to the valley below. No one was caught. The group had dug a previous pit and found fair to good stability. This proves the snowpacks spacial variability. The weak layer is unclear. No CNFAIC Staff reports of any signs of instability in the area.
Areas of concern today include hanging snow fields in complex terrain. Old wind slabs may be present. Weak layers may be closer to the surface and able to be triggered where the snowpack is shallower. Take time to test the snow you are traveling on. Keep the human factors in check today. Stability may be moderate, but this kind of snow, weather and stability can still produce dangerous avalanches.
Snowfall totals from Monday’s storm at the highway elevation snow stakes at Turnagain Pass were 31 inches at Eddies, 31 inches at the Motorized lot, 22 inches at Sunburst, and 19 inches at Johnson Pass.
Glide cracks are secondary concern today since this new load of snow is still actively settling and moving. A full depth release avalanched a couple days before Monday’s storm in Girdwood Valley (see photo gallery). Glide cracks are like cornices in that they are wild cards that are very difficult to predict.
WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST FRI MAR 12 2010
.TODAY…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. HIGHS 15 TO
25. VARIABLE WIND TO 10 MPH. NEAR WHITTIER…WEST WIND 10 TO 20 MPH.
.TONIGHT…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS 10 TO
20 ABOVE. VARIABLE WIND TO 10 MPH.
.SATURDAY…SNOW LIKELY. SNOW ACCUMULATION UP TO 2 INCHES. HIGHS
AROUND 30. VARIABLE WIND 10 MPH EXCEPT NORTH 15 TO 25 MPH NEAR
.SATURDAY NIGHT…SNOW LIKELY. LOWS IN THE 20S. NORTH WIND 10 TO
15 MPH EXCEPT NORTH 20 TO 30 MPH NEAR SEWARD.
.SUNDAY…SNOW LIKELY. HIGHS IN THE 30S. NORTHEAST WIND 10 TO
15 MPH EXCEPT NORTH 15 TO 25 MPH NEAR SEWARD.
.SUNDAY NIGHT…SNOW LIKELY. LOWS IN THE UPPER 20S TO LOWER 30S..
TEMPERATURE / PRECIPITATION
SEWARD 19 14 31 / 40 40 70
GIRDWOOD 26 14 29 / 30 30 40
WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800′-Sunburst Wx Station
Current Temp: -3 (3 degrees warmer than yesterday)
Winds: sensor not working this morning
2600′-Seattle Ridge Wx Station
Winds: sensor not working this morning
1800′-Center Ridge Wx Station
Current Temp: 0
Precip: 0, total snowpack 131 after anCNFAIC Staff 2 inches of settlement.
Thanks for checking today’s avalanche advisory. The next one will be posted tomorrow Saturday March 13, 2010.