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Thu, Mar 21, 2019 at 7:15 AM
Issued by: Chris Bilbrey

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

With each passing day, it becomes harder for a rider to trigger an avalanche. However, if you do trigger an avalanche it most likely will be very large and inescapable. They can potentially break wide across terrain features and run to valley bottoms. Avoidance or sticking to lower angled slopes with no avalanche terrain above you is the only sure way to avoid avalanches. If you choose to venture into steeper terrain, you most likely won’t see an obvious sign of danger before an avalanche breaks – shooting cracks or audible collapses. Carefully evaluate all terrain around you and consider the consequences for not only your group but others that might be nearby.

Our next storm system arrives today with snow at higher elevations. With warm air already in place, the rain/ snow line could climb to near 10,000 feet. Localized heavy snowfall could be exciting for short periods – hail, thunder, and high precipitation intensity are all possible. Snowfall looks to favor areas south and west of Red Mountain Pass. Heads up for thin storm slab formation near and above treeline and expect thicker drifts along ridge tops and in cross-loaded terrain features. New cornice growth and smooth, rounded pillows will clue you into heavily wind-loaded slopes. Anticipate an increase in loose wet activity below treeline from rain on snow and if you observe rollerballs or pinwheels, move higher in elevation or choose a different activity.

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Avalanche Problem

 
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N
S
E
W
NW
NE
SE
SW
Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
Small
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

 
problem icon
N
S
E
W
NW
NE
SE
SW
Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
Small
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
SW
Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
Small
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.

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 10 to 15
Wind Speed (mph) 15 to 25 15 to 25 10 to 20
Wind Direction S SW W
Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy
Snow (in) 3 to 6 1 to 4 0 to 2

Archived Forecasts

  • Select Forecast: Valid

Thu, Mar 21, 2019 at 8:00 AM
Issued by: Chris Bilbrey Statewide Weather Forecast  

Our next storm system moves into the Great Basin today. Warm and moist air arrives on south flow and highest snowfall totals look to favor the South San Juan and Sangre de Cristo zones. Warm air already in place makes nailing down the rain/ snow line a challenge. We anticipate rain on snow up to near 10,000 feet at the onset before moving to around 9,000 feet or lower. Localized, heavy snowfall during the day is forecast to become more widespread overnight. Today could be a good day to pack a second jacket if venturing out in the mountains.

The warm nature of our storm will keep snowfall totals from appearing all that impressive. However, dense snow can quickly form into a cohesive slab. Slopes with more than six to eight inches of new snow should be evaluated before blindly jumping in. Pay attention to snow totals as you climb in elevation and look for cracking in the new snow to clue you into storm slab formation. New snow is falling onto a variety of old snow surfaces and can move fast and far downslope where it falls onto a slippery surface – melt-freeze crust or firm wind-board.

Rain on snow will make for messy conditions below treeline. If you observe heavy rain or rain continues for prolong period, you should anticipate an increase in wet snow activity. This will most likely start with loose wet avalanches but could transition to wet slabs if enough rain falls. Rollerballs will clue you into the snow surface becoming wet and loosing cohesion. Wet slabs are more likely in steeper, rocky terrain. If you see signs of loose wet activity, consider moving up in elevation or getting off said slopes. Pay attention to terrain above you if traveling in creek bottoms or above cliffs at lower elevations. 

A lower likelihood but much bigger consequence problem is weak layers buried under a 1.5 to 2 meter cohesive slab. These layers have produced many large to very large avalanches this season. During our most recent dry spell the snowpack continued to settle, stiffen, and made triggering an avalanche in deeper weak layers more difficult. When weak layers are buried as deeply as they are, digging into the snow is difficult, time consuming, and snowpack test often don’t give reliable information about instability. A rider is most likely to trigger one of these monster slides from thin rocky areas or near margins of a slab – this is where weak layers are closer to the surface. Avoid travel below large, overhanging cornice. If a piece of a cornice breaks off and goes tumbling down a slope, that could be a large enough trigger to cause one of these Deep Persistent Slab avalanches to fail. Don’t linger in avalanche runout zones and if you have to cross a runout, do so quickly.

It really comes down to the terrain you wish to ride and your risk acceptance. This may be different from person to person – having good communication amongst partners and making a solid plan is important. Many folks will slowly step out into steeper terrain and many will ride away without triggering a massive avalanche. Carefully evaluate terrain above and below you and consider the consequences of not only those in your group but those near you. Good habits save lives so make a plan that fits the current avalanche conditions, stick to it, and only expose one person to a slope.

 


  • CAIC Forecasters traveled in the South San Juan zone to evaluate the snowpack after a historic avalanche cycle - not only in the San Juan's but throughout the state. Despite a lack of obvious signs of instability, we still need to be diligent with our snowpack evaluations and terrain selection. Lots of snow and numerous large to very large avalanches observed warrants a step back until the snowpack has time to adjust to the recent load.
  • Natural deep slab avalanche south of Trout Lake, North San Juan zone. Estimated to run 3/13/19. (full)
  • Snowpit on an east aspect at 11,900 feet. (full)
  • E-SE aspect of Red Mountain. South of Lake City. (full)

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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 Mon Mar 18 Mark Mueller No Yes (4) Yes (4)
View Mon Mar 18 Mark Mueller No Yes (1) Yes (2)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Beartown Thu Mar 21 2:00 PM 29 - - - - 2.0
Dynamo Telluride Ski Resort Thu Mar 21 4:00 PM 19 95 16 76 56 -
Putney Thu Mar 21 3:00 PM 19 95 18 115 35 -
Swamp Angel Thu Mar 21 3:00 PM 25 90 3 294 11 2.5
El Diente Peak Thu Mar 21 2:00 PM 30 - 3 112 - 2.0
Lizard Head Pass Thu Mar 21 2:00 PM 33 - - - - 1.0
Lone Cone Thu Mar 21 2:00 PM 33 - - - - -
Moon Pass Thu Mar 21 3:00 PM 32 - - - - 2.0
Slumgullion Thu Mar 21 3:00 PM 34 - - - - 2.0

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