|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.
Though yesterday was a quiet day in the backcounty, we did get a number of late observations from Sunday. The first was a remotely triggered slab on Silvertip Peak (Easterly facing 4,900′). Two on Sunburst – Northerly facing ~3,500′ and on southerly facing ~3,500′ (this south facing slide is a couple days old). And the last, but most noteworthy, in the Girdwood Valley (West facing ~4,100′). Note each of these slabs reported are on each of the 4 aspects.
The image below is of the Girdwood Valley avalanche. This was in an area known as Surprise Bowl (see map in link above). Details are still emerging but it seems one party unintentionally triggered an avalanche that caught one of them and partially buried two people from another party while ascending the skin track below. Check the observations page for more reports sent in to us regarding this slide. This incident brings up many topics related to safe travel practices and etiquette when multiple groups are recreating in the same area. There have been a number of close calls regarding multiple groups around the country as well as last year’s accident at Pete’s North. Good habits keep us safer. And that is why even when a slope is littered with tracks and all seems well that we still play one at a time, watch our partners and wait for other goups below (even well below) to pass.
For today – It may be spring and it may have been a week now since our last snowfall, but the cold weather and buried facets surrounding crusts are keeping slab avalanches active. Most of these are old wind slabs that are sitting on a crust with a thin layer of weak snow sandwiched between. That said, we have a persistent slab concern littered about at the upper elevations. On notherly aspects we are seeing smaller shallow wind slabs sitting on old faceted snow but lack the crust bed surface.
The best way to mitigate these slabs is to do quick test pits and hand pits. As well as keep a close eye out for wind loaded slopes and cracking and collapsing (whoomphing). Much of the activity we have seen is in the upper 18″ of the pack. It doesn’t take long to poke in that far. Also, traveling one at time and always having an exit route planned if the slope releases is key.
Sluffing in the steeper terrain on shaded aspects should again be expected today. As for the southerly aspects, including many east and westerly slopes, the sun did a number yesterday. Many of these became damp and have refrozen overnight. With today’s daytime heating, pay attention to any softening of surface crusts. In this case, watch for wet loose and shallow wet slabs to become a concern. We are expecting some cloud cover later in the day which could keep surface warming limited.
Cornices. Don’t forget to steer well clear of these monsters. They have been baking in the sun each day and are due to come tumbling down any time.
Bears. It seems the bears are waking up. A recently opened den was seen in upper Lyon Creek yesterday, area just north of Pastoral Peak.
Yesterday was another clear and pleasant day. Winds stayed light and variable and temperatures rose to the mid 20’sF on the ridges and upper 30’sF at 1,000′. The last measurable snowfall was on April 9th. Overnight, skies have remained clear and temperatures have dropped to the mid teens in most areas with the usual cold pools (i.e., Summit Lake and Portage) in the single digits. Winds have remained light and variable.
Today, our clear skies may be replaced with clouds in the afternoon and maybe even a flurry as a weak low pressure system tries to move in from the Gulf. Winds are forecast to remain light from a northeast direction (5mph on ridgetops). Temperatures look to rise to the 20’sF on the ridgelines and mid 30’sF at 1,000′.
Our dry spell looks to continue for the remainder of the week.
The next advisory will be issued Thursday morning, April 18th.
|Observation: Silvertip Creek
|Observation: Seattle Ridge
|John Sykes Forecaster
|Observation: Kickstep NE Bowl
|Observation: TinCan Backdoor/ Center Ridge
|AAS L1 Turnagain
|Avalanche: Lynx Creek
|Observation: Turnagain, Seattle, Mt Ascension
|Silverton Mountain Guides
|Observation: Tincan Trees
|Dalpes/Thamm/ Schauer Forecaster
|Observation: Seward Highway across from Johnson Pass TH