November 13 UPDATE
Active weather this week
This morning’s storm is expected to favor Anchorage and Girdwood over Turnagain Pass and the eastern Kenai. Heavy snowfall will be immediately followed by strong northerly winds. Graphic courtesy of NWS Anchorage, 11.13.2023.
Stormy weather has returned to Southcentral this morning, and avalanche danger will be on the rise as another pulse of snowfall will be quickly followed by strong northerly winds. As we gain a little more insight from the early season snowpack, we are beginning to see that we will be dealing with several avalanche concerns. Here is what you need to know:
Storm and Wind slab concerns
This round of stormy weather is expected to bring up to a foot of snow to the Chugach Front Range and 8-10″ to Girdwood, with more modest totals of 4-8″ to Turnagain Pass and Summit Lake. Snow levels should stay low with mixed precipitation possible up to around 500′. Visit the NWS Anchorage homepage to see more information on Winter Storm Warnings and Blizzard Warnings for the area. The quick shot of snow will be immediately followed by strong northerly winds at 20-25 mph with gusts around 45 mph. Prior to this storm, we noticed a widespread layer of surface hoar on the surface, with the most well-developed (and problematic) surface hoar crystals at higher elevations (details in this observation). With the combination of new and wind-loaded snow sitting on top of a widespread surface hoar layer, we can expect to see avalanches failing in at the new/old snow interface. These will be 1-2′ deep and will likely be very sensitive and easy to trigger, with the chances for natural avalanches increasing as winds pick up this afternoon. Because these surface hoar layers are a type of persistent weak layer, we should anticipate sensitive conditions to last longer after the storm than a typical storm/wind slab problem will last. Be on the lookout for dangerous conditions to continue into the week.
Deeper Persistent Weak Layer concerns
As we saw from Saturday’s avalanche incident on Goldpan (details here), the old snow that was on the ground prior to last Thursday’s storm event has the potential to make big avalanches failing near the ground. These can be 3-6′ deep, and have the potential to be triggered remotely or after there have been multiple sets of tracks on the slope. This avalanche problem exists at elevations above 3000′ or so, and likely gets worse at higher elevations where there was more snow on the ground prior to the 11/9 storm. These deep persistent problems are difficult to assess; they seldom give typical warning signs like shooting cracks or collapses even when conditions are ripe for triggering an avalanche. If you are trying to get up into higher elevations as the skies clear this afternoon, be especially skeptical around steep and rocky terrain where it is most likely to find unstable snow. As mentioned previously, the storm and wind slab concerns with this storm should already be reason enough to avoid the steeps, but this deeper problem dramatically increases the potential size and consequences of triggering an avalanche.
CHUGACH STATE PARK
Based on the observations coming in from CSP (see more from Gordon Lyon, Rendezvous Peak, and North Bowl), we know we are dealing with an early season snowpack with similar poor structure. This storm is expected to favor the mountains near Anchorage, placing a heavy load on a snowpack that has already shown warning signs. Expect avalanche danger to increase rapidly starting this morning, and be cautious with terrain choices as you travel.
This avalanche in Goldpan released sympathetically after a skier triggered another avalanche in an adjacent chute just to the right of this frame. The skier was able to ski off the slab, but this was a scary near miss that clearly shows us the potential for big avalanches at upper elevations. Photo: Mike Records 11.11.2023
This snowpit from Sunburst yesterday shows the structural problem we are currently dealing with. Photo: George Creighton, 11.12.2013
All of that sparkly surface hoar that made for great skiing yesterday will be cause for concern as it gets buried by new and windblown snow today. 11.12.2023
Chugach NF Avalanche Center – early season operations:
- The Avalanche Center will issue intermittent weather and avalanche updates as conditions warrant through mid November.
- Daily avalanche forecasts are planned to begin around Thanksgiving week.
**PLEASE, send us your reports if you head into the mountains. It’s easy – even just a photo is greatly appreciated.
Avalanche rescue gear and communications:
- Is your rescue gear working properly?
- Beacons (avalanche transceivers) – fresh batteries
- Probes – able to assemble properly with no weak points in the cable
- Shovels – not damaged and is a true avalanche shovel
- Airbags – charged, working properly, and tested
- InReach up to date and associated with the correct emergency contacts
POSTPONED: Southcentral Alaska Avalanche Workshop – now Nov 17, 9:00am to 4:30pm
- Alaska’s Annual snow science workshop (SAAW) is all set to happen this Friday, November 17. Visit akavalancheworkshop.org for the most up to date information. This event is geared for both snow professionals and public backcountry users alike. If you are a snow/avalanche geek, this is the event for you!
Nov 17, 7:00pm- MSP Ski Film!
- MatchStick Productions – “The Land of Giants” – Trailer HERE.
Showing at the West Anchorage High School Auditorium. Doors open at 6pm.
Tickets HERE ($20 in advance and $25 at the door).