Good morning backcountry travelers. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Thursday, April 21th at 11am. We are no longer issuing daily avalanche advisories for 2010-2011 season however, this does not mean that the avalanche season is finished. See below for an update for the Turnagain Arm area (this does not apply to highways, railroads, or operating ski areas).
Outside advisory area:
Our deepest condolences go out to the family and friends of Dale Brabec who was killed while sledding on his saucer in the Bird Ridge area between Anchorage and Girdwood. Details are being compiled by the Alaska Mountain Rescue Group and will be posted as they become available.
The “shed cycle”, meaning the big spring thaw when many slopes shed their snow, is close to arriving. Several medium, and a few large, wet loose and wet slab avalanches have begun to release naturally. In particular, these have been seen on east facing slopes both on Seattle Ridge in Turnagain Pass and Raggedtop in the Girdwood Valley.
Wet snow avalanche concerns
The most dangerous avalanche conditions in the Turnagain Arm area remain the shedding of wet snow on east, south and west facing slopes. Human triggered avalanches are likely and natural avalanches are possible on these slopes. Wet avalanches entrain very dense and heavy snow and are hard to escape from. They can push you into trees, over cliffs and into gullies. The KEY clue to watch for is when springtime snow becomes soft and slushy enough that your boot penetrates ankle deep. This is often in the afternoon as the snow warms through the day, however can be any time of day if temperatures are too warm for the snow to refreeze overnight. Steer clear of any slopes with wet soft snow.
Dry snow and new snow/rain concerns:
New snow and rain are on tap for the end of the week through the weekend. By the weekend the rain/snow like looks to increase to 2000′ and possibly higher. Winds currently look to be moderate and increase from the east over the weekend. As with any new snow, keep an eye out for recent avalanches as well as cracking and collapsing. Human triggered soft slab and wind slab avalanches will be possible in areas receiving over a few new inches. The minute the sun pokes out and hits the new snow wet loose natural and human triggered avalanches will be likely. Remember, avalanche danger is highest during and within 24 hours after the storm, after which it will begin to decrease. If the rain line increases to over 2000′ wet snow avalanches will be likely. These can be on all aspects and could be large depending on the amount of rain that falls.
GENERAL AVALANCHE DISCUSSION
There are still plenty of weak layers out there including: pockets of buried surface hoar, facets around sun crusts and facets surrounding the Thanksgiving rain crust.
Avalanches on these weak layers are possible, especially:
-within 24 hours after storms
-during rain on snow events
-during the big spring thaw
-during times of direct sunlight
-rapidly warming temperatures
**Every year there is a time when the snowpack completely falls apart due to the spring thaw. This can happen any time in the next couple weeks. Often, this extremely dangerous avalanche cycle starts after 2-3 days of sustained above freezing temperatures at the ridge top weather stations (including overnight), during periods of direct sun or intense rainfall. When the spring thaw happens, we all need to stay away from the mountains until the cycle is finished. Large destructive avalanches that could fail on deeper weak layers are common during this time.
The place for all things weather is the CNFAIC weather page!
We would like to thank all of you for staying safe in avalanche terrain and helping make this avalanche center an important resource for South Central Alaska and the Kenai Peninsula.
A HUGE THANK YOU goes out to everyone that submitted observations this year. Your observations are invaluable to us, as well as help steer this operation in the right direction.
We’d also like to thank the Friends of the Chugach National Forest Avalanche Information Center and our major funding partners. You are an amazing group of folks with a passion to help keep people safe in the backcountry. THANK YOU for all your support.
Additionally, we would like to thank:
-Alyeska Ski Patrol
-Alaska Avalanche School
-Alaska Pacific University
-Chugach Powder Guides
-and many CNFAIC Staffs
for sharing important avalanche information to pass on to the backcountry community.
Remember – Stay tuned for periodic updates through April 30th.
Thanks for checking the avalanche advisories this season. Have a great spring and summer!