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Thu, Mar 21, 2019 at 7:13 AM
Issued by: Ben Pritchett

Today

 

Tomorrow

Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
Low (1) Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
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Summary

Your chances of triggering a very large avalanche are getting smaller by the day. Your best bet is to minimize your exposure to large steep alpine terrain that hasn't run yet.

Though unlikely, it’s not impossible that you could wake up an alpine beast of an avalanche in shallow and variably snow-covered alpine terrain. If you do, the consequences would be catastrophic. Avoid these shallow spots because you’re most likely to trigger something from an area of weak snow where broad alpine slabs taper to less than about a 2-3 feet thick. Regroup in safe areas that simply can not be hit by an avalanche. You’d have to be unlucky to trigger something, but you can still reduce your risk by making good choices about where and how to travel.

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Avalanche Problem

 
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N
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Above Treeline
Near Treeline
Below Treeline
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Historic
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Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Deep Persistent Slab avalanches are destructive and deadly events that can release months after the weak layer was buried. They are scarce compared to Storm or Wind Slab avalanches. Their cycles include fewer avalanches and occur over a larger region. You can triggered them from well down in the avalanche path, and after dozens of tracks have crossed the slope. Avoid the terrain identified in the forecast and give yourself a wide safety buffer to address the uncertainty.

Avalanche Problem

 
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N
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E
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NE
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Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
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Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Loose Wet avalanches occur when water is running through the snowpack, and release at or below the trigger point. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

Avalanche Problem

 
problem icon
N
S
E
W
NW
NE
SE
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Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
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Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

Weather Forecast for 11,000ft Issued Thu, Mar 21, 2019 at 1:10 PM by Spencer Logan Statewide Weather Forecast
  Thursday Night Friday Friday Night
Temperature (ºF) 15 to 20 25 to 30 15 to 20
Wind Speed (mph) 10 to 20 10 to 20 10 to 20
Wind Direction S W W
Sky Cover Overcast Mostly Cloudy Mostly Cloudy
Snow (in) 4-7W/2-5E 1 to 4 0 to 2

Archived Forecasts

  • Select Forecast: Valid

Thu, Mar 21, 2019 at 7:54 AM
Issued by: Ben Pritchett Statewide Weather Forecast  

Deep Persistent Slab avalanches are scary. Their consequences are ultimate. They are unsurvivable. In addition, they are fickle and hard to predict. Your best bet is to avoid where they could happen, which are large avalanche paths that did not run huge in March.

The pattern is pretty clear. During our historic first two weeks of March, these huge avalanches ran from large alpine and near treeline avalanche paths, on all aspects. The snowpack structure that led to these avalanches remains in place on many slopes that did not avalanche in March. You can recognize these slopes that have not avalanched by their smooth and deep looking snow cover. When you compare the lack of avalanche evidence on these to the slopes that did slide, it's not too difficult to distinguish which is which. Grey skies and flat light today may obscure the picture, so if in doubt, assume it hasn't gone yet.

The slopes that did avalanche are easy to identify given a few key observations. They have deep debris piles near the bottom of the paths, many chock-full of broken trees. In the start zones, the crowns of snow above these old avalanches remain visible. Depending upon when the big avalanche released, you'll find none to several feet of snow deposited on the old bed surfaces. So far, we've received no reports of avalanches on the March bed surfaces. In general, there the basal weak layers in these paths are dramatically disturbed, and the fledgling slabs not very stiff. It's worth investigating the potential of a thinner Persistent Slab avalanche on one of these bed surfaces, but to the best of our knowledge there's been no slab avalanches running again on the slopes that released in early March.

The Deep Persistent Slab avalanche problem is not as prevalent on the Grand Mesa or anywhere below treeline. Although it has become unlikely for you to trigger a deep avalanche, it is not impossible in isolated terrain features. Wet loose snow sluffing is the primary concern. You can easily manage these types of problems by moving onto shady, cooler slopes as the snow begins to warm.

 


  • Emerald Lake (full)
  • East face Baldy 12k/10k (full)
  • Cornice fall triggered slab off of Scarp Ridge (full)
  • Poverty Gulch filled with many 10's of feet of debris. (full)
  • Historic avalanching off the west and southwest side of Purple Ridge. (full)
  • A very large debris pile from an avalanche off the west side of Anthracite Mesa. (full)

See more photos & videos

Five Day Trend

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Avalanche Observations
No relevant backcountry observations found for this forecast

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Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Wed Mar 20 Murray Cunningham No Yes (1) Yes (2)
View Mon Mar 18 Eric Murrow No Yes (2) Yes (3)
View Mon Mar 18 Alex Tiberio No No Yes (1)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Butte Thu Mar 21 2:00 PM 42 - - - - -
Elkton Thu Mar 21 3:00 PM 30 63 11 153 26 -
Snodgrass Mt Thu Mar 21 2:10 PM 36 45 5 13 - -
Park Cone Thu Mar 21 2:00 PM 40 - - - - 1.0
Taylor Park Thu Mar 21 2:57 PM 40 43 7 129 16 -

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