Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Monday, January 10th 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).
A huge thanks goes out to everyone who submitted observations this past weekend! In order to keep the observations coming, we’re adding a little bit of incentive. Each time you send in an observation…and this means quality and timely observations and photos from the Turnagain Arm area….your name will be entered in a drawing to be held at the end of each month for a $100 gift certificate from the Friends of the CNFAIC. The gift certificate is good for use at any of our sponsors’ businesses. At the end of the year everyone’s name goes back into the hat for the grand prize…an avalanche beacon of your choice.
Today the avalanche danger has decreased to MODERATE overall. While natural avalanches are unlikely today, human triggered avalanches still have the potential to go big. I think ‘Scary Moderate’ is actually a better description of the overall hazard. The conditions right now may allow you to play on the same slope all day, but the 20th person will trigger the whole thing, erasing the old tracks. The 20-30 inches of new snow from last week’s storm fell on an exceptionally weak snowpack littered with multiple layers of buried surface hoar, weak sugary snow, and facets above and below the Thanksgiving Rain Crust (TRC). The most likely spot to trigger an avalanche today will be in shallow areas of the snowpack near rock outcrops or windscoured ridges.
Avalanche activity tapered off this past weekend. Many folks played in steeper terrain yesterday and didn’t trigger anything. We are, however, still finding signs of instability in the form of clean fast Q1 shears in our snowpit tests (mainly on facets below the TRC) and reports of whoomphing in certain areas. The problem with the snowpack right now is the unpredictable nature of our persistent weak layers. We are seeing a gradual increase in stability, but I still don’t trust anything steep. The trigger spots will be harder to find as time goes by, but if you do find one, be prepared for a potentially large avalanche. Future snowloads could possibly “reactivate” the persistent weak layers as well, so keep a heads up if the winds increase and load leeward slopes.
Also keep in mind that recent large human triggered avalanches happened a full 60-72 hours after the storm. The most recent reported human triggered avalanche happened late Friday afternoon when a skier remotely triggered a medium sized avalanche on Sunnyside just south of the snowmachine uptrack. Also on Friday, a snowboarder was fully buried in an avalanche in the Palmer Creek area near Hope. The rider was the fourth person down the slope and triggered the slab near a scoured area of rock on top of a convex rollover in mellow benched terrain (see photo below). All of our recent avalanches failed on buried surface hoar or facets near a crust or both.
Here’s a rundown of recent avalanche activity:
-Large natural avalanches observed on Sunnyside (east aspect), Sunburst (south aspect), Upper Girdwood Valley (south aspect), and Main Bowl (north aspect).
-Skier triggered avalanche on south face of Raggedtop, triggered on buried surface hoar from a chute higher up then propagated down across the face, stepped down to deeper weak layers, crown face 6-8 feet deep at thickest spot.
-Skier triggered avalanche in Warmup Bowl off Seattle Ridge, triggered near some rocks in a shallow area, large propagation across slope, partially buried a snowmachine parked at the bottom of the slope.
-Snowmachiner triggered avalanche in the Seattle Creek drainage, avalanche released above rider while performing a slope cut.
-Full burial of snowboarder in Palmer Creek drainage near Hope. Rider was fourth person down the slope. Avalanche triggered near a scoured area of rock on top of a convex rollover; slab failed on facets underneath a crust.
-Skier remotely triggered a medium sized avalanche, approx. 300 feet wide, on east face of Sunnyside near snowmachine uptrack. Fracture propagated uphill.
-Large avalanche on Widowmaker, Seattle Ridge. Unknown trigger.
-Small avalanche on west face of Lips, started near rocks at top. Unknown trigger.
-explosive work in upper Girdwood Valley produced limited results.
Encyclopedia of terms: www.fsavalanche.org/Encyclopedia.aspx
Under partly cloudy skies yesterday, temperatures hit the upper 30’s at the higher elevations while sea level temps remained in the mid teens. Our most recent storm that ended 5 days ago dropped 20-30 inches of new snow (2.7” water) over a 5 day period in Turnagain Pass. Skies have been clear since the storm and the winds generally light. A 25 degree temperature inversion exists this morning with Sunburst at 3800′ reading 34F and sea level at 10F. Winds are currently light and skies are clear. Ridgetop winds are forecasted to pick up a bit this afternoon, averaging 10-20mph out of the northeast, while skies will remain clear.
Jon 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 MON JAN 10 2011
.TODAY…MOSTLY SUNNY. HIGHS IN THE LOWER 20S TO MID 30S. NORTHWEST
WIND 5 TO 15 MPH.
.TONIGHT…CLEAR. LOWS IN THE MID TEENS TO LOWER 30S…COOLEST
INLAND. NORTHWEST WIND 10 TO 15 MPH EXCEPT NORTH 15 TO 30 MPH
.TUESDAY…SUNNY. HIGHS IN THE LOWER 20S TO MID 30S…COOLEST
INLAND. NORTHEAST WIND 10 TO 20 MPH EXCEPT NORTH 20 TO 35 MPH NEAR
.TUESDAY NIGHT…CLEAR. LOWS ZERO TO 25 ABOVE…COOLEST INLAND.
NORTHEAST WIND 10 TO 20 MPH EXCEPT NORTH 25 TO 35 MPH NEAR SEWARD.
.WEDNESDAY…SUNNY. HIGHS IN THE LOWER TEENS TO LOWER 30S…
COOLEST INLAND. NORTHEAST WIND 15 MPH EXCEPT NORTH 20 TO 35 MPH NEAR
TEMPERATURE / PRECIPITATION
SEWARD 31 23 32 / 0 0 0
GIRDWOOD 26 19 25 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded light and variable winds the last 24 hours. Temps yesterday ranged from 32F to 38F. The current temp is 34F with light winds out of the west.
-2600′ Seattle Ridge Wx Station-
recorded light and variable winds the last 24 hours with a few moderate gusts last night (Thanks Forest!!). Temps yesterday ranged from 27F to 34F. The current temp is 34F with light winds.
-1800′ Center Ridge Wx Station-
recorded no new snow the last 5 days. Temps yesterday ranged from 20F to 26F. The current temp is 27F with a total snowpack depth of 68 inches (1 inch of settlement in the last 24 hours).