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Observation: Big Cottonwood Canyon

Observation Date
4/26/2020
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon
Location Name or Route
Big Cottonwood Canyon
Weather
Sky
Clear
Precipitation
Light Rain
Wind Direction
West
Wind Speed
Light
Weather Comments
Overnight lows from 11,000 feet down did not have a refreeze. This is also the second night in a row that there was not a refreeze from 9000 feet down. Light rain fell overnight and there was thick cloud cover until 1000 hours this morning.
Snow Characteristics
Snow Surface Conditions
Damp
Snow Characteristics Comments
Wet, not damp.
Red Flags
Red Flags
Recent Avalanches
Rapid Warming
Poor Snowpack Structure
Red Flags Comments
The Natural Avalanche reported from the Y-Couloir was no surprise. It tops out at 9600 feet and as stated above, we have not had a refreeze from at least 9000 feet and down for two nights now. The potential for a Wet Loose to begin in the upper reaches of this confined area and entrain significant amounts of snow was Likely. Tonights forcast for the second night of no refreeze up to the highest peaks with rain up to 10,000 is a definite Red Flag of concern. Wet Slabs may be possible from at least 9000 feet, and aspects on the upper half of the compass are prime suspects for these dangerous avalanches. An Avalanche Warning may be indicated because of these sustained high temperatures.
Avalanche Problem #1
Problem
Wet Snow
Trend
Increasing Danger
Problem #1 Comments
Wet Loose at all elevations, and especially on the aspects on the upper half of the compass are Very Likely. Much of the northerly facing terrain has not fully transitioned to a solid spring snowpack. Large extremely dangerous Wet Slabs are Likely from elevations at and around 9000 feet on Monday. And, with the forecast for extremely warm temperatures throughout the week, these issues may be Possible at all elevations. Care should be taken on Monday night (and beyond) to follow the data from the remote weather stations for freezing levels. Along with this, clear skies RH values of 50% also help promote refreezes when the temperatures are hovering around freezing.
Avalanche Problem #2
Problem
Cornice
Trend
Increasing Danger
Problem #2 Comments
These same unseasonably warm temperatures can also enhance the possibility for Cornices to release Naturally as well as be human triggered. These large Cornices may also break much further back on the ridge lines than expected. Finally, these Cornices may trigger large Avalanches upon decent.
Comments
Great caution and care should be taken to stay off of and out from under any steep terrain.
Today's Observed Danger Rating
High
Tomorrows Estimated Danger Rating
High