Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday March 20th, 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).
2010: Telepalooza AK & Alyeska World Comp March 23 – 28, 2010 Check out details at http://www.alyeskaresort.com The event will have Telemark demos, lessons, races, a beacon park event and a raffle. The raffle has HUGE prizes and all raffle proceeds benefit the Friends of the Chugach National Forest Avalanche Center and this advisory. See you there!
Yesterday mornings storm yielded 15 inches of snow in Turnagain Pass, 3 inches at Johnson Pass North TH, 9 inches at Eddies and Sunburst parking lots, and 9-12 inches at Alyeska. The snow line was approximately 800 feet. Skies cleared in the late afternoon. This mornings radar shows limited precip. The satellites show moderate cloud cover moving in from the southwest. Very limited chance of precipitation today. Winds let up significantly yesterday. Moderate east winds this morning at ridgetop elevations.
Today’s avalanche danger level is CONSIDERABLE
Considerable means natural avalanche are possible and human triggered avalanches are likely. Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision making essential.
We received over an inch of water and 10-15 inches of snow 24 hours ago. This new snow is resting on suncrusts on many south and southwest aspects. Yesterday afternoon we started to see clouds part and the sun shine through. Point releases and loose snow avalanches were present most of the day but nothing to major. Late in the day the sun intensified and point releases actually triggered small slab avalanches on south aspects. Expect more of the same today.
If the sun is out and temperatures reach the forecasted mid thirties, the avalanche hazard will increase. You will likely trigger avalanches if that is the case. Spring time is the time to get earlier starts and get back to the trailhead mid afternoon. Get off of and away from steep sun baked south and southwest slopes if the temperature rises into the mid to upper thirties. Yesterday’s snow is actively settling and is actually forming a cohesive slab of snow. I have seen this type of setup in the past produce significant slab avalanches. It will all depend on the specific underlying snowpack where you are traveling. Does it have a weak layer in it?
Proof of the weak layers present lie in the multiple human triggered avalanches we saw over the last week. See a full detailed list by checking the 03-18-2010 advisory in the archive. In the spring we start to see many layers in our snowpack. Wind, sun, rain, snow, faceting, all form funky layers in the snow. These layers will be harder and harder to track. You will have to rely less on reports and advisories and more on your ability to interpret the snow in front of you. Spacial variability becomes common place in the spring. One slope may have great stability and 100 ft away on a westerly aspect the stability may be death on a stick.
Take time to evaluate conditions this weekend. I would dial it back for a couple days and see how this layer sets up. My biggest concern lies in alpine south to southwest aspects where buried sun crusts exist.
Glide cracks are secondary concern today. These crevasse like features that are cracks that go all the way to the ground appeared to have opened up a bit more over the past 2-4 days. Glide cracks are like cornices in that they are wild cards that are very difficult to predict. Stay far away from these cracks today since they are actively moving right now.
WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
500 AM AKDT SAT MAR 20 2010
.TODAY…AREAS OF FOG IN THE MORNING. MOSTLY CLOUDY WITH SCATTERED
RAIN AND SNOW SHOWERS. HIGHS AROUND 40. VARIABLE WIND 10 MPH.
.TONIGHT…PARTLY CLOUDY. A SLIGHT CHANCE OF SNOW SHOWERS IN THE
EVENING. LOWS IN THE LOWER 20S TO LOWER 30S. LIGHT WINDS EXCEPT
NORTH 10 MPH NEAR SEWARD.
.SUNDAY…PARTLY CLOUDY. HIGHS IN THE MID 30S TO LOWER 40S. LIGHT
WINDS. NEAR SEWARD…NORTH WIND 10 TO 15 MPH IN THE MORNING
.SUNDAY NIGHT…MOSTLY CLOUDY. LOWS IN THE LOWER 20S TO LOWER
30S. LIGHT WINDS. NEAR SEWARD…LIGHT WINDS BECOMING NORTHEAST
10 MPH AFTER MIDNIGHT.
.MONDAY…MOSTLY CLOUDY. HIGHS IN THE MID 30S TO LOWER 40S. LIGHT
WINDS EXCEPT NORTH 15 MPH NEAR SEWARD.
TEMPERATURE / PRECIPITATION
SEWARD 42 26 41 / 40 20 0
GIRDWOOD 41 22 40 / 0 0 0
WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800′-Sunburst Wx Station
23 degrees F, average east winds in the teens with gust in the twenties.
2600′-Seattle Ridge Wx Station
26 degrees F, with average southeast winds in the teens and gust into the twenties.
1800′-Center Ridge Wx Station
26 degrees F, 0 new snow, 135 inch total snowpack after 5 inches of settlement.
Lisa will update this advisory tomorrow morning Sunday March 21, 2010 by 0700. Thanks and have a great day.