UDOT PLANNED AVALANCHE CLOSURES!!
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Observation: Ant Knolls

Observation Date
1/6/2020
Observer Name
Meisenheimer, Staples
Region
Provo » American Fork » Ant Knolls
Location Name or Route
Snake Creek to Ant Knolls
Snow Characteristics
New Snow Depth
5"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
5 inches of new snow overnight. Great riding and great cold powder even on south aspects.
Even at 6800 feet at the trailhead at Wasatch State Park, there were 2-3 inches of new snow (photo).
Red Flags
Red Flags
Wind Loading
Poor Snowpack Structure
Red Flags Comments
This morning, we noted the wind continuing to drift snow off the upper elevation ridge lines. By later afternoon the wind died and it was calm and sunny. No more plumes off the peaks. A weak layer and slab does exist on southerly aspects so I decided to check the poor snowpack structure box.
Avalanche Problem #1
Problem
Persistent Weak Layer
Problem #1 Comments
We were hunting for this problem and dug around 15 snowpits on all aspects between 9000 and 9300 feet. It's an interesting problem. We found it on South (including SW & SE). We could not find it on North, East or West. What was interesting is that on a flat south-facing slope (15° or less), it did not exist because sun hits a flat south facing slope at a low enough angle that most of the sunshine is reflected. We performed many extended column tests on this layer, and we found that it was most likely to propagate on slopes with just the smallest amount of wind loading.
Comments
Photo: Layer in between 2 crusts - it was buried 14 inches deep at this location (S aspect, 9300 ft)
Video
On a north aspect, this layer/structure didn't exist and it was just good powder riding. Photo: Snowpit with no weak layers (NW facing 9,300'). All tests were ECTN.
We discussed this crust/faceted weak layer a lot today, and here are our thoughts:
  1. Because it's located shallow in the snowpack it is easy to dig down and look for it. It only takes 2 minutes to perform and Extended Column Test. If it propagates, that's bad. If it doesn't that's good. However, it might exist in a different location! The main strategy is that if you find the crust, pick a different slope like a northerly facing one. Or stick to terrain at or under 30° degrees in slope steepness.
  2. The timing of when this crust/facet combo formed was so brief that the slightest thing like a cloud or the shade of a tree might have prevented it from forming altogether.
  3. We THINK that it needs just the tiniest bit of wind loading or wind affect on a slope for it to produce an avalanche. It needs just a little extra weight or slab formation to see propagation in the snowpits we dug.
  4. We THINK (NOT 100% SURE) that East didn't get enough sun and warmth to create this crust/facet combo. It's likely when this event happened that it was too cold or too cloudy to effect the east facing terrain.
  5. We are unsure if this is a problem on West aspects. We were not able to dig on that aspect today.
  6. This weak layer formed between Christmas and New Years. It will cause avalanches in the short term but we don’t expect it to be a very long lasting problem.
Today's Observed Danger Rating
None
Tomorrows Estimated Danger Rating
None
Coordinates