Observation: Red Pine Gulch

Observation Date
2/2/2021
Observer Name
Zimmerman-Wall / Grainger
Region
Salt Lake » Little Cottonwood Canyon » Red Pine
Location Name or Route
Red Pine
Weather
Sky
Overcast
Wind Direction
South
Wind Speed
Strong
Weather Comments
Split personality weather. Cloud deck dropped from above ridgeline to below 10,000' between 0530 and 0730. Wind increased out of the south mid morning. Transporting surface snow even at the mid elevations. Temps were balmy down at TH in the predawn hours. Gradual temperature increase throughout morning. No new snow. Sunny below 9800 feet after 10 am and this was a stark difference from the conditions above treeline.
Snow Characteristics
Snow Surface Conditions
Powder
Wind Crust
Damp
Snow Characteristics Comments
In the alpine the snow surfaces generally had some wind effect but skied well enough. Mid elevation had soft settled powder from the storm over the weekend but was wind effected in many locations. Lowers had notable surface deterioration from green housing. Roller balls and pinwheels abound.
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Red Flags Comments
Alpine terrain was experiencing active loading from the moderate to strong Southerly winds. Mid elevation drifting occurring throughout tour.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
Slopes are more connected and the layer of concerns is becoming more deeply buried in the core of the Wasatch.
Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #2 Comments
In upper LCC the winds were transporting and reloading paths that had slid during the natural cycle on 1/30/21. These new drifts and wind slabs will be covered up by the new snow tomorrow and it will be hard to tell exactly where the problem lies.
Snow Profile
Aspect
Northeast
Elevation
9,700'
Slope Angle
10°
Comments
Goals of the day: 1. Target uncertainty with regards to what slide paths ran during the last cycle (1/30/21) and what has yet to release in the alpine terrain of Red Pine/Maybird. 2. Map surface conditions ahead of the next loading event. We were pleasantly surprised to see that upper Red Pine went through an extensive natural cycle. The entirety of the upper north through east facing portion of the drainage (Lake Shot et al) had run and debris reached almost as far as the Lower Red Pine Lake. The effects of the wind event from 1/27-1/28 and the subsequent snowfall (40cm) allowed for the larger slopes to be connected for the first time during the season. It was truly amazing to see crowns that wrapped around terrain features and aspects. Even down in the rolling terrain above the lake we were able to see evidence of significant avalanches in unusual places. Would be difficult to call any of these greater than D2.5 due to the nature of the slab. Although the Lake Shot path has significant relief, the crowns were only around 90cm-1.25 m deep and the flanks quickly tapered to 50-60 cm. Although it took out the majority of the snow cover from the season, there just wasn't that much volume in the deposition zones at the toe.
Small test slopes at mid elevation on the way to Maybird provided solid evidence that the snowpack was still adjusting and we triggered one small avalanche by kicking a cornice feature on a steep rollover.
While it was clear the majority of the hazard had relived itself in the alpine, would expect many of these paths to reload and possibly repeat. There is still weak snow left in the bed surfaces. And the mid elevation slopes that did not run may still be suspect. Although our snow pit showed that the mid pack has become quite stout above the 20201211 layer, the facets will need more time to undergo the effects of pressure and sintering. But maybe in certain places we are putting the right dynamics in place to gain strength. Until then, the avalanches are going to be large and un-survivable if triggered.
Photos:
Upper Drainage crowns
Photos
Lower Lake slide and test slope after cornice kick.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates