Turnagain Pass |
Archives |
The avalanche danger is expected to rise to CONSIDERABLE in the higher elevations this afternoon due to heavy snowfall and moderate winds. Both slab avalanches and loose snow sluffs composed of the new snow could release naturally and human triggered avalanches are likely in areas seeing more than 8″ of snowfall. In the lower elevations and in the trees, the danger is expected to remain MODERATE for the possibility of triggering shallow slab and loose snow avalanches within the new snow that falls later today.
*The National Weather Service has issued a Winter Weather Advisory:
We’re looking for your input! We’ve made some changes to the forecast this year, and we are curious to hear how well it has worked. This is your chance to give us some feedback that will help us continue to improve our forecasts. These advisories are for you and we want to know how we can make them better. We’ve put together a quick survey that should take 5-10 minutes to complete. If you have a chance, please Click here for the survey. We really appreciate your feedback.
Travel Advice | Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. | Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. | Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. | Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. | Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain. |
Likelihood of Avalanches | Natural and human-triggered avalanches unlikely. | Natural avalanches unlikely; human-triggered avalanches possible. | Natural avalanches possible; human-triggered avalanches likely. | Natural avalanches likely; human-triggered avalanches very likely. | Natural and human-triggered avalanches certain. |
Avalanche Size and Distribution | Small avalanches in isolated areas or extreme terrain. | Small avalanches in specific areas; or large avalanches in isolated areas. | Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. | Large avalanches in many areas; or very large avalanches in specific areas. | Very large avalanches in many areas. |
A few small wind slabs were observed Friday afternoon with the increase in winds and a couple inches of new snow. Otherwise, it has been almost two weeks since the last human triggered large avalanche on a deep persistent weak layer that we are still concerned about.
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
A cold winter storm is moving in that will bring snow to sea level. This system is coming from the west, unlike most of the snowfall events we see. That means the winds are blowing from the west to northwest and should drift the new snow in unusual ways. The peak in the storm is forecast for this afternoon into this evening, meaning avalanche danger won’t rise until later today when up to a foot to 18″ could fall in the Placer/Portage Valleys and closer to 8-12″ is forecast for Girdwood and Turnagain Pass. That said, avalanche danger will be directly related to how much new snow falls.
The main concern will be avalanches composed of the new snow. Depending on how much snow falls and how strong the winds are, we could see all types of storm snow instabilities. These are wind slabs in the higher elevations up to 2′ thick, storm slabs on slopes out of the wind in areas with over 8″ of new snow, and loose snow sluffs. The old snow surfaces are a mix of sun crusts, wind crusts, and old settled powder. We can expect the new snow to slide off all these surfaces quite easily in areas that really do see heavy snowfall.
For today, paying attention to the new snow amounts and any wind loading will be key. Keep an eye out for recent avalanches, how the new snow is sticking to the old surfaces, and any cracking in the new snow around you. Don’t forget there is a slow-to-heal weak layer buried far below, discussed in Problem 2.
24-hour snowfall forecast starting Sunday morning. Graphic from NWS Anchorage 4.9.23
Sun crusts as of Friday, two days ago. These crusts exist on east through south and west facing slopes – and even a few northerly aspects were reported to have a thin crust. It will provide a slick bed surface for the new snow to pile up onto. Photo by Megan Guinn, 4.7.23.
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
We are still concerned about the low likelihood but high consequence deep slab problem. This is due to a layer of weak snow around 3-6′ deep in the snowpack that was buried in mid-March. After a rash of human triggered deep slab avalanches two weeks ago, the past week has seen signs that this weak layer is gaining some strength. That said, we don’t want to be too quick to dismiss it altogether (more details in these observations from Bertha Creek and Pete’s North).
Although new snow will add a little stress to this layer today, it is’t likely enough to overload it. Meaning it is still unlikely for a deep slab to release, but it isn’t wholly out of the question. Continuing to use a cautious mindset and safe travel protocols to minimize exposure is recommended.
Taylor Pass viewed from below the Sunburst weather station on Friday. Winter remains despite being April! Photo by Megan Guinn, 4.7.23.
Yesterday: Mostly cloudy skies were over the region with a few snow flurries. Between a trace to 2″ of snow was seen through the day. Ridgetop winds were northwesterly in the 5-10mph range with gusts in the teens. Temperatures climbed to the mid 20’sF during the afternoon and have dropped into the teens and single digits overnight.
Today: A cold storm is moving in that will bring between 8-18″ of new snow. Highest amounts are expected in Portage Valley. Snowfall should begin in earnest early this afternoon. Ridgetop winds will remain northwesterly and blow 10-15mph with gusts in the 20’s. Temperatures look to stay cool, in the teens in most mountain locations (20’sF at sea level).
Tomorrow: Cloudy skies and light snowfall is expected to linger through Monday. An additional 1-4″ is forecast. Ridgetop winds swing around easterly and look to be in the 10-15mph range with stronger gusts. Temperatures remain cold for April, in the teens to 20’sF.
PRECIPITATION 24-hour data (6am – 6am)
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
---|---|---|---|---|
Center Ridge (1880′) | 25 | 0 | 0 | 88 |
Summit Lake (1400′) | 24 | 0 | 0 | 44 |
Alyeska Mid (1700′) | 22 | 2 | 0.1 | 83 |
Bear Valley – Portage (132′) | 28 | 3 | 0.23 | – |
RIDGETOP 24-hour data (6am – 6am)
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
---|---|---|---|---|
Sunburst (3812′) | 14 | W | 5 | 12 |
Seattle Ridge (2400′) | 16 | NW | 4 | 11 |
Date | Region | Location | Observer |
---|---|---|---|
10/27/24 | Turnagain | Observation: Tincan | Michael Kerst |
10/21/24 | Turnagain | Observation: Turnagain Pass Road Observation | Trevor Clayton |
10/19/24 | Turnagain | Observation: Tincan – Below Todds Run | Andy Moderow |
10/18/24 | Turnagain | Observation: Taylor Pass | Eli Neuffer |
10/15/24 | Turnagain | Observation: Tincan Common | John Sykes Forecaster |
10/14/24 | Turnagain | Avalanche: Tincan | CNFAC Staff |
05/13/24 | Turnagain | Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South | H Thamm |
05/13/24 | Turnagain | Observation: Turnagain Pass non-motorized side | Amy Holman |
05/12/24 | Turnagain | Observation: Warm up Bowl | Tony Naciuk |
05/07/24 | Turnagain | Observation: Turnagain Pass Wet Slabs | A S |
The riding areas page has moved. Please click here & update your bookmarks.
Subscribe to Turnagain Pass
Avalanche Forecast by Email