ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Thursday November 29th, 2018
Posted by Heather Thamm on 11/29/18 at 7:00 am.
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  in the Alpine where triggering a slab avalanche is possible on all aspects. Below 2500′ the danger is  LOW where freezing temperature are helping a thin and wet snowpack form a crust.  

2. Moderate
Alpine
/ Above 2,500'
Avalanche risk
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1. Low
Treeline
/ 1,000'-2,500'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0. No Rating
Below Treeline
/ Below 1,000'
Avalanche risk

Special Announcements

The Friends of the CNFAIC have two scholarships dedicated to avalanche education. The funds generated to make these possible are in celebration of Rob Hammel and Amy Downing, their love and passion for the mountains, and to help others stay safe. We encourage you to read each one and apply if you fit the need, or pass along to someone who could benefit.  Applications due on Dec 1st.

Rob Hammel Scholarship Fund   €“ For recreational users and professional avalanche workers.

Amy Downing Scholarship Fund   €“ For recreational users.

Avalanche Problem 1
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
  • TYPE
    Storm Slabs
  • Chance
    Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size
    Historic
    Very Large
    Large
    Small

Last night was the first freeze in five days since a series of warm and wet storms ended yesterday morning.  Not much snow exists below 2000′ due to heavy rain that may have reached ridgetops at times. We don’t have a lot of information from the upper elevations, above 2500’, at this point. We know 4+’ of snow fell over a four-day period and strong Easterly winds have loaded leeward features and cross-loaded other aspects. Prior to this storm a melt-freeze crust and surface hoar formed in the upper elevations. We don’t know how much avalanche activity occurred during the storm and if this poor structure is lingering in places that haven’t avalanched.

Today triggering an avalanche is possible in the Alpine and could be large enough to bury a person. If you hike into the Alpine where there is enough snow to slide ease into avalanche terrain with a cautious mindset. We are still in the 48-hour period since heavy snow and strong winds formed storm slabs. Avoid avalanche terrain if you observe any signs of instability: recent avalanches, shooting cracks, or whumpfing

Webcam pictures from DOT weather station provided our first glimpse into the Alpine yesterday afternoon – Northern and Western aspects of Tincan above 2000′. 

 

 

Brief clearing in the afternoon provided a nice glimpse of an Eastern aspect of Seattle Ridge. Note how little snow exists in the lower elevations.

 

 

West aspect of Butch in foreground and Northern aspects of Tenderfoot and Tri-Tip in the background. Photo from Mon Nov. 26  at Lower Summit Lake.

Mountain Weather

Yesterday: Moderate Easterly ridgetop winds diminished yesterday morning becoming light by early evening. Skies were obscure most of the day a broken period late afternoon. Temperatures dropped below freezing last night allowing 0.1 € of snow water equivalent to fall as an inch of snow to sea level from Girdwood to Turnagain Pass last night.

Today: Scattered snow showers and a trace of snow are possible this morning with clearing skies in the forecast this afternoon. In the upper elevations temps will average in the low 20Fs and upper 20Fs near sea level.   Winds will remain light and variable.

Tomorrow: Temperatures will start to increase as another storm moves into our region Friday into Saturday. This storm will have a Southwesterly flow, which typically favors Hatcher Pass for precipitation. Temperatures are expected to reach above freezing and rain is likely in the mid and lower elevations. Increasing temps and winds are expected in the Western Chugach and Kenai Mountain.

 *Seattle Ridge weather station stopped collecting wind data at 10 pm on Nov 27, 2018.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 29    1″ 0.1   10  
Summit Lake (1400′) 27   0   0   0  
Alyeska Mid (1700′) 30   1″ 0.16   *N/A  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 21   ENE   5   27  
Seattle Ridge (2400′) 26   *N/A   *N/A     *N/A