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Observation: Mary Ellen Gulch

Observation Date
2/4/2024
Observer Name
Zimmerman-Wall
Region
Provo » American Fork » Mary Ellen Gulch
Location Name or Route
Sinner's Pass/Mary Ellen Gulch
Weather
Sky
Few
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Winds shifted from NW to SW by 13:00. Speeds increased to Moderate. Visible transport off the AF Twins late afternoon. Temps below ridgeline were below freezing but the February sun felt strong.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Low
Snow Surface Conditions
Powder
Damp
Snow Characteristics Comments
The new snow was bonded well to the old snow surfaces on eastern and southern aspects. By 11 am the East surface was quite damp below 10,000'. South was next to go by 1230. Southwest was warming by 1400. These aspects will sport a zipper+ tomorrow. A supportable melt freeze crust from the prior high pressure exists below the storm snow on southerly aspects and is 3cm thick and up to Pencil hardness. A thin layer of facets exists underneath but were not reactive in stability tests. North aspects were cold and dry. Natural dry loose avalanches on slopes stepper than 35 degrees noted. Easily initiated with skis along ridge lines. HS in this area is over 2 meters in places. Some shallow zones near ridge line on Southerly were noted, but not that common.
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #1 Comments
Plenty of evidence of wind slabs that pulled out with explosives around the ski area periphery above 10,500' on cross loaded NE facing terrain. However, there was no wind slab noted in Mary Ellen Gulch or Pagan Basin.
Avalanche Problem #2
Problem
New Snow
Problem #2 Comments
Storm and dry loose noted in some steep features just off ridge lines. This has mostly settled out as of this morning and evidence was not always obvious.
Comments
The goal today was to see how the new snow had bonded to the old snow surfaces on southerly aspects and to look for evidence of wind slab formation in the alpine. I observed snowmobilers playing on low consequence steep slopes without issue in Mary Ellen. The crust beneath the new snow on southerly aspects was supportable enough on skis and provided a bit of rebound under the 30cm of right side up storm snow. Powderbird stacked tracks in open terrain of upper AF and looked to be just stepping out into their circuit. No signs of instability from the tracks I saw in Outhouse and Terrace Runs.
I avoided convoluted and unsupported terrain features with consequential run outs. I did ski slopes steeper than 30 degrees facing south on this solo tour after investigating the bond and not seeing obvious signs of instability. The most suspect slopes were mid and upper elevation facing north and in larger terrain in the alpine where the weak layer was closer to the surface near rocks or where the wind had made the slab thinner. I simply did not tangle with that nonsense. Plenty of very good surface conditions below the wind and on planar terrain features.
Photos:
Sinners SW Profile image. The 3cm crust down 35cm was supportable on skis. The snowmobilers I talked to said as soon as they stopped giving throttle, the track would stay on top of this crust and their backend would wash out down slope, making side hilling tricky.
Mary Ellen Gulch with snowmobile tracks. Noted covered storm slab debris at base of Outhouse Chutes.
Natural Dry Loose avalanches on Northeast facing slopes on Pagan Shoulder
Storm slab debris visible in the center of Pagan basin. Looked like it ran during the height of the storm and traveled a few hundred feet. Similar to the debris piles at bottom of Outhouse Chutes
Dry Loose from skis and mini-cornice along Sinner's Pass
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
None
Coordinates