ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Tuesday March 5th, 2019
Posted by Aleph Johnston-Bloom on 03/05/19 at 7:00 am.
Avalanche risk
The Bottom Line
Low Avalanche Danger
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

A generally  LOW  avalanche danger remains across the advisory area. Triggering a slab avalanche is unlikely. Watch for sluffing on steep shaded slopes, avoid travel under glide cracks and give cornices a wide berth. Pay attention to changing conditions.

 

1. Low
Alpine
/ Above 2,500'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1. Low
Treeline
/ 1,000'-2,500'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1. Low
Below Treeline
/ Below 1,000'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

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Avalanche Problem 1
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
  • TYPE
    Normal Caution

After a beautiful sunny day in the mountains clouds moved back into the area overnight. There is a chance of snow today and increased easterly winds but this should not have much impact on avalanche hazard. Watch for changing conditions if more snow falls than forecasted.

Today will be another day of Normal Caution (LOW danger). Things to keep in mind if you are headed into the backcountry:

  • Glide avalanches – These types of avalanches are highly unpredictable and not associated with human triggers. It’s always best to watch for and limit exposure under glide cracks.
  • Dry-loose sluffs – Watch your sluff on steep shaded slopes.
  • Cornice falls – As always, give cornices a wide berth. 
  • An outlier slab avalanche – Although it is unlikely a person could trigger a slab avalanche, the mountains can harbor surprises, especially in thin snowpack areas. South of Turnagain in the Summit Lake and Silvertip zones there is a shallow snowpack with a generally poor structure. A variety of old weak layers (facets and buried surface hoar) sit in the mid and base of the snowpack. The most suspect place to trigger an avalanche is steep terrain with old, hard wind slabs sitting on weak snow. 
  • Considering the consequences before entering into committing terrain and maintaining good travel protocol are good habits to keep on LOW danger days.

In anticipation of snow, we have been closely mapping the surface conditions as well as watching for new surface hoar growth. Surface hoar has been observed from valley bottoms to the Alpine and is resting on a variety of surfaces. There is a stout sun crust on southerly facing slopes. On shaded aspects 4-8″ or so of soft near surface facets sit over a firmer base and sastrugi, wind crust and/or rime crust can be found along ridgelines. The question is will it snow just enough today to bury the surface hoar and will we call it the “Fat Tuesday/Mardi Gras” weak layer? Hopefully some surface hoar will be knocked over by the wind!

Surface hoar, Tincan, 3-4-19. Photo: Eeva Latosuo

Sun crust with surface hoar and stellars (from Sunday), Twin Peaks, 3-4-19. 

Mountain Weather

Yesterday: Partly cloudy skies becoming mostly sunny. There was some valley fog in the morning. Winds were light and temperatures were in the teens to 20Fs at upper elevations and in the 30Fs at sea level. Overnight clouds moved in and winds picked up slightly. Temperatures were in the teens to 20Fs.  

Today: Mostly cloudy skies with a chance of snow showers. Winds will be southeasterly 5-15 mph with gusts into the 20s. Temperatures will be in the 20Fs. Overnight looks to be similar with winds becoming calm.    

Tomorrow: Continued cloudy skies with a chance of snow, calm winds and temperatures in the 20Fs. A more promising storm still looks to be on track for the weekend.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  25  0 0   58  
Summit Lake (1400′)  19  0  0     27  
Alyeska Mid (1700′)  24   0    0     53  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  17  E 4   18  
Seattle Ridge (2400′)   22     E    5     14