Special Avalanche Advisory Issued: Sunday, February 17, 2019 at 6:00 AM
Expires: Monday, February 18, 2019 at 9:00 AM

A strong storm on Thursday night brought 1 to 2 feet of dense snow with strong winds to the mountains. Avalanche conditions remain dangerous especially in the Central and Southern Mountains. You can trigger avalanches that break in the new and wind drifted snow that will be large enough to bury or kill you. You may even be able to trigger very large very dangerous avalanches that break deeper in the snowpack. If you trigger one of these deeper avalanches it will most likely be inescapable. Consult the Zone Summary for the areas you are planning to travel for specific information and travel advice. Make sure you carry an avalanche transceiver, shovel and probe and know how to use all of your gear. You can always limit the chance of being caught in a dangerous avalanche by sticking to lower angle terrain without steeper connected avalanche slopes above you.

  • Backcountry Avalanche Forecast
  • Forecast Discussion
  • Observations & Weather Data

Sun, Feb 17, 2019 at 7:05 AM
Issued by: Mike Cooperstein

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.
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.
  Danger Scale

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Summary

Winds continue to drift snow into slabs on north and easterly slopes. Open wind-prone areas near and above treeline that face north through east to south are the most dangerous and should be avoided. Looks for signs of recent wind-loading such as cornices along ridgelines, smooth pillows of drifted snow, and drifts behind terrain features to identify potentially dangerous slopes. If you trigger an avalanche in or just below the recently wind-drifted snow it can be large and can also step down to more deeply buried weak layers resulting in a very dangerous avalanche that will be large enough to bury you. Stick to wind-sheltered or lower elevations terrain to reduce your risk of triggering an avalanche.

 

Avalanche Problem

 
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Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

Avalanche Problem

 
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Above Treeline
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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.

Avalanche Problem

 
problem icon
N
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NE
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Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
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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.

Weather Forecast for 11,000ft Issued Sun, Feb 17, 2019 at 12:27 PM by Mike Cooperstein Statewide Weather Forecast
  Sunday Night Monday Monday Night
Temperature (ºF) -10 to -5 0 to 5 -10 to -5
Wind Speed (mph) 10 to 20 10 to 20 10 to 20
Wind Direction S SSW SSW
Sky Cover Mostly Cloudy Mostly Cloudy Overcast
Snow (in) 0 to 2 0 to 2 0 to 2

Archived Forecasts

  • Select Forecast: Valid

Sun, Feb 17, 2019 at 7:39 AM
Issued by: Kreston Rohrig Statewide Weather Forecast  

With less total snowfall over the past few days than other zones and new slabs that are proving to be more stubborn than reactive, the Vail & Summit County and Front Range zones have dropped back to Moderate (2 of 5). That said, there are plenty of dangerous slopes out there, and any steep wind-loaded terrain should be thoroughly investigated or avoided altogether. With 3 to 7 inches of low-density snow from yesterday combined with up to 15 inches of total storm snow from the past three days, newly formed slabs will be 2 to 3 feet thick on leeward slopes. Expect a wide distribution of wind slabs on north to east to south facing aspects near and above treeline from shifting southwest to northwest winds. On these same slopes, there is potential for any avalanche triggered in the new snow to step down to weaker layers buried deeper in the snowpack. It may be harder to effect these layers, but the resulting avalanches will be huge and hard to escape.

In the Steamboat/Flat Tops, avalanches triggered in the new snow will keep the danger elevated. With many feet of new snow on the ground, you can trigger avalanches in the storm snow deep enough to bury you. This is especially concerning around terrain traps like creek beds and gullies where even a smaller avalanche can pile up deep. Drifted areas will also be more dangerous as the new snow will be deeper, denser and more cohesive; all the things needed to create larger more deadly avalanches. If that wasn't enough, you will also need to consider loose snow "sluffs" if traveling around steep terrain. Yesterday's snow was much lower density and may easily fail beneath your skis or sled. This type of avalanche is usually harmless, but could be a problem if you get swept off your feet or pushed into a tree. 

Bottom line: We are slowly creeping out of another good storm cycle and avalanche conditions will need time to settle. There is plenty of good snow and riding options on slopes under 30 degrees. Seek these out to reduce your chances of triggering an avalanche today.

 


  • View of a hard slab avalanche that was released by mitigation on February 14, 2019 in the Stanley slide path on Berthoud Pass.The avalanche appears to have started in a layer of near-surface faceted crystals about 60cm deep and then stepped down to depth hoar at the ground. (full)
  • View of a hard slab avalanche that was released by mitigation on February 14, 2019 in the Stanley slide path on Berthoud Pass.The avalanche appears to have started in a layer of near-surface faceted crystals about 60cm deep and then stepped down to depth hoar at the ground. (full)
  • HS-AX-R2-D2.5-G Whistler slide path February 15, 2019. This avalanche stepped down to weak snow at the ground and broke wider than expected.This is a southwest-facing aspect near treeline. (full)

See more photos & videos

Five Day Trend

Thursday

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Today

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Avalanche Observations
Report Date # Elevation Aspect Type Trigger SizeR SizeD
View Sun Feb 17 - >TL SE SS N R1 D1

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Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Sun Feb 17 Sean Fearon No Yes (1) Yes (4)
View Fri Feb 15 Mike Cooperstein No No Yes (4)
View Thu Feb 14 Tara Vessella No No Yes (1)

See All Field Reports

Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Bear Lake Sun Feb 17 5:00 PM 14 - - - - -
Bottle Peak Sun Feb 17 5:50 PM 2 88 4 86 5 -
Berthoud Pass Sun Feb 17 6:00 PM 1 71 6 223 10 -
Cameron Pass Sun Feb 17 6:00 PM 2 83 3 145 4 0.1
Joe Wright Sun Feb 17 4:00 PM 14 - - - - -
Loveland Basin Sun Feb 17 4:00 PM 14 - - - - -

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