ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Wednesday April 3rd, 2019
Posted by Heather Thamm on 04/03/19 at 7:00 am.
Avalanche risk
The Bottom Line
Moderate Avalanche Danger
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

The avalanche danger is MODERATE due to the possibility of glide avalanches releasing naturally. Identify terrain with glide cracks and plan your route to avoid travel directly below these unpredictable hazards. Triggering a wet loose avalanche is possible in the afternoon and evening on steep Southern aspects. Monitor surface conditions and transition to firmer slopes if the surface snow becomes wet and unsupportable. Give cornices an extra wide berth.

PORTAGE VALLEY: Summer trails with avalanche terrain overhead, such as Byron Glacier Trail and Crow Pass, are still not recommended in the afternoon or evening due to the possibility of an avalanche occurring above.

SUMMIT LAKE (& INTERIOR EASTERN KENAI MTS): Human triggered slab avalanches remain possible in upper elevation terrain on all aspects. This area has a thin snowpack with many weak layers. Evaluate snow and terrain carefully.

SEWARD/LOST LAKE: Similar to the Turnagain Area travel on solar aspects should be carefully evaluated later in the day and travel under glide cracks should be avoided.

2. Moderate
Alpine
/ Above 2,500'
Avalanche risk
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2. Moderate
Treeline
/ 1,000'-2,500'
Avalanche risk
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2. Moderate
Below Treeline
/ Below 1,000'
Avalanche risk
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Special Announcements

Avalanche Problem 1
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. The are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
  • TYPE
    Glide Avalanches
  • Chance
    Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size
    Historic
    Very Large
    Large
    Small

Glide cracks are scattered throughout the advisory area and have been avalanching daily. Yesterday morning two new glide avalanches were seen in Turnagain Pass on Southwest aspects of Eddies and Corn Biscuit. In the early evening Magnum’s Southwest face had a fresh new glide avalanche. Glide avalanches are full depth avalanches that have the potential to be very dangerous. They are not associated with human triggers and occur spontaneously without warning. Glides can release even if a hard surface crust is present (unlike the wet loose and wet slab avalanche problems). Many glides are releasing in areas where folks are entering/exiting popular terrain. The best way to manage this problem is to identify them and avoid travel under their runout zone. Remember they can release at any time!

New glide avalanche on Magnum’s SW face released yesterday afternoon.

 

Corn Biscuit (left) has a lot of new glide cracks and a new glide avalanched overnight on Monday. Lipps (right) glide crack has widened significantly in the last two days. 

 

 

Seattle Ridge has seen a lot of glide avalanches and wet avalanches over the last week and a half. Be aware that glide cracks are still opening up and have the potential to cross the uptrack, like one that released on Saturday. 

Additional Concern
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
  • TYPE
    Wet Loose

LOOSE WET: Overall the possibility of natural wet loose and wet slab avalanches has decreased over the last two days. The snowpack has seen many days of a springtime melt-freeze pattern and many low to mid elevation terrain has shed (avalanched) a lot snow. In the Alpine, where night time temps have dropped well below freezing, a firm surface crust has formed. Today with daily warming and sunny skies there is still potential for a person, on skis or a machine, to trigger an avalanche in the afternoon/evening on solar aspects. If the snow surface breaks down and becomes wet and punchy, it’s time to get onto shaded slopes or off the one you are on.

CORNICES: Cornices are very large and direct sunshine can make them easier to trigger in the afternoon. Give cornices a wide berth and avoid travel directly below where one might fall.

South of Turnagain in Summit Lake and areas in the interior Kenai Peninsula have a very poor snow structure with variety of old weak layers within the snowpack. This poor structure is most suspect in the alpine above 3000’ – on shaded aspects any time of the day or on steep solar aspects late in the afternoon when surface crusts start breaking down. Triggering a persistent slab 2-3’ deep is becoming less likely with time, but not out of the question. In the mid and lower elevations where a stout crust as formed, monitor surface conditions and adjust your plans if the surface snow is unsupportable on Solar aspects later in the day. 

Mountain Weather

Yesterday: Skies were sunny in the morning with high clouds moving in the afternoon. Temperatures reached the mid 40Fs in the mid and lower elevations. Ridgetop temps reached the mid 30Fs and dropped to the mid 20Fs overnight. Ridgetop winds were 5-15mph from the West. No precipitation fell.

Today: Skies will be partly cloudy to clear. Daytime temperatures are expected to reach the mid 40Fs in the mid and lower elevations. In the alpine daytime temps will be in the 30Fs and overnight will drop into the 20Fs. Winds are expected to be light from the Northwest with some areas seeing moderate NW winds (20s mph) like Turnagain Arm. No precipitation is expected.

Tomorrow: Skies could range from mostly cloudy with broken skies at times. There’s a chance for a few flurries in the alpine, but no accumulation is expected. Winds will shift to an Easterly direction and increase into the 10-20mph range in the afternoon. Saturday looks like our first opportunity for a storm to bring a few inches of snow to the alpine and rain showers to lower elations. Stay tuned!

PRECIPITATION 24-hour data (6am – 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 37   0   0   66  
Summit Lake (1400′) 36   0   0   21  
Alyeska Mid (1700′) 38   0   0   58  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 27   W   6   18  
Seattle Ridge (2400′) 34   WNW   2   10