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Sunday, May 20, 2018 at 3:11 PM Issued by: Brian Lazar  

Weather Outlook:

On Sunday afternoon Colorado sits under southerly flow as the jet stream rounds the bottom of a deep low-pressure trough along the west coast. There is enough moisture to generate some scattered light snow above 11,000 ft Sunday night, favoring the northern San Juan Mountains, the Sawatch Range, and the Continental Divide from Loveland Pass north to around Rocky Mountain National Park. Accumulations by Monday morning will be an inch or two at best. By Monday the low-pressure system closes off over northern California and slowly drifts south then east towards the Four Corners. Daytime highs climb into the low 50s under partly to mostly cloudy skies. Another pulse of moisture pushes in Monday night, and we could see up to 4 inches of snowfall in the San Juan Mountains with maybe half that in eastern reach of the Central Mountains. Nighttime lows at 11,000 ft stay a few degrees above freezing.

Tuesday starts out dry and then scattered thunderstorms come into the picture for Tuesday afternoon with daytime highs again climbing into the low to mid 50s.  Lows once again hover a bit above freezing. On Wednesday the low-pressure system slides across Colorado as an open wave bringing drier southwest flow to the area. High-pressure begins to build by Thursday. 

 

Backcountry Avalanche Conditions:

Most mountain ranges picked up a scattered 1 to 5 inches of snow in the last 24 hours. The deepest numbers .  are from Hoosier Pass northeast to Berthoud Pass and the west side of the Rocky Mountain National Park as well as a few spots in the Flat Tops. The winner looks to be the Tower SNOTEL site north of Steamboat with 5 inches.  Another dusting of snow Sunday night, and then some better snow on Monday night in the Central and Southern Mountains will freshen up the snow surface. You may be able to trigger avalanches that break at the new snow old snow interface. These avalanches should be relatively small and manageable, but may be large enough to knock you off your feet and take you for a ride. When the sun breaks through the cloud cover Loose Wet avalanches will become possible in all areas that received new snow. Pay attention to changing conditions depending on snowfall amounts and cloud cover over the next few days.

Our most recent observations indicate a snowpack with only a weak surface freeze below 12,000 ft or so.With moist to wet snow underneath the surface, Loose Wet avalanches could gouge to the ground and be very dangerous if you are caught in the dense flowing debris.

A recent large Wet Slab avalanche in the Sawatch Range near Leadville shows us we are not done with avalanche season.These avalanches could release on one of several ice lenses in the middle of the snowpack or break into moist facets at the ground. You might trigger the slides, or they may break unexpectedly as water trickles through the snowpack. It can be very hard to guess how the water is flowing through the deep snowpack layers, so avoiding steep terrain can be the best way to avoid these avalanches.

Your best bet for safe travel is to get into the mountains early, and plan to be out of avalanche terrain by mid-morning. Thin snowpack areas and/or rocky slopes are particularly suspect, as they will be the first to become saturated from top to bottom and release as wet slides breaking to the ground.

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You can check current weather conditions on the Weather Stations page. You can see where recent avalanches occurred and other observations on the Field Reports page. Let us know what you see out there by Submitting an Observation.

We will issue a Statewide Avalanche Summary on Sundays, Wednesdays and Fridays through Memorial Day. As conditions change we will update this product any time it is warranted.

 
  • Looking down towards the toe of debris. Large wet avalanche near Leadville. Likely ran around 5.17.18 (full)
  • Large Wet Slab avalanche near Leadville. The crown is visible. Likely ran around 5.17.18 (full)
  • Smaller tree branch in the debris. Large Wet Slab avalanche near Leadville. Likely ran around 5.17.18 (full)

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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 Sun May 20 Tom Caprarella No No No
View Sat May 19 Brad K No No Yes (3)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Bear Lake Sun May 20 6:00 PM 42 - - - - 1.0
Steamboat Lake State Park Sun May 20 6:00 PM 49 82 4 284 7 0.9
Bottle Peak Sun May 20 6:00 PM 40 52 11 238 14 -
Berthoud Pass Sun May 20 6:00 PM 30 94 12 239 26 -
Cameron Pass Sun May 20 5:00 PM 43 61 2 6 5 -
Grand Mesa - Skyway Point Sun May 20 7:00 PM 41 53 5 149 15 1.5
Kendall Mt Sun May 20 6:00 PM 36 48 9 183 26 -
Loveland Pass Sun May 20 6:00 PM 31 100 4 45 16 -
Molas Pass Sun May 20 6:00 PM 45 47 6 25 16 1.3
Putney Sun May 20 6:00 PM 39 62 6 114 15 -
Swamp Angel Sun May 20 6:00 PM 43 64 3 89 11 1.0
Wolf Creek Pass Sun May 20 6:00 PM 39 56 8 64 15 -
Monarch Pass (050e200) Sun May 20 6:44 PM 32 99 3 160 6 -
Columbus Basin Sun May 20 5:00 PM 50 - - - - -
Lizard Head Pass Sun May 20 5:00 PM 54 - - - - -
Medano Pass Sun May 20 6:00 PM 44 - - - - -
Mesa Lakes Sun May 20 6:00 PM 46 - - - - -
Ripple Creek Sun May 20 5:00 PM 50 - 1 105 - 1.0
Slumgullion Sun May 20 6:00 PM 38 - - - - -
Schofield Pass Sun May 20 6:00 PM 42 - - - - -
Storm Peak Observatory Sun May 20 6:10 PM 42 61 10 142 15 -
Taylor Park Sun May 20 5:57 PM 43 64 5 164 11 -
Wolf Creek Summit Sun May 20 6:00 PM 50 - - - - -
Zirkel Sun May 20 6:00 PM 47 - - - - -

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