Observation: Aspen Grove

Observation Date
Observer Name
Provo » Provo Canyon » North Fork Provo R. » Aspen Grove
Location Name or Route
Bob's Knob to UFO Bowl aprons
Light Snowfall
Wind Direction
Wind Speed
Weather Comments
A few snowflakes at 11am hinting at the storm. Quiet, then a few more snowflakes at 3pm. Warm. Aspen Grove clocked in at 40-42°F during the day. Marginal refreezes at Sundance mid-mountain since the 24th. Winds were moderate in the mid-elevations and approaching strong along the high peaks (Cascade Ridgeline photo).
Snow Characteristics
Snow Surface Conditions
Faceted Loose
Wind Crust
Melt-Freeze Crust
Snow Characteristics Comments
Travel was only to 9000'.
Supportable melt freeze crust on low/mid-elevation solars; breakable on off aspects. Shady aspects have a mix of rounding near surface facets (pic 1), dendrites, and laying over and some-times baked-in surface hoar (4mm) denoted by yellow lines - (pic 2,3). Initially I was fearing the worst as I was "sand-boxing" on the uptrack on the polar aspects, but found that this was not due to weak facets but instead graupel (pic 4).
More on what this might mean ahead of tonight's storm below.
Red Flags
Red Flags
Wind Loading
Avalanche Problem #1
Wind Drifted Snow
Increasing Danger
Problem #1 Comments
Winds from the southwest blew in the moderate range, ramping up toward the strong category by late-morning. A couple skiers who had been skiing this terrain for 20 years triggered some new soft slabs of wind drifted snow 4" deep and 30' wide along the top of the UFO Bowls ridgeline and pulled the plug. They could see the writing on the wall.
Cascade ridgeline photo of winds...
Snowpack depths at 8800-9000' were roughly 175-200cm and the snow was mostly* stable. (Repeater avalanche terrain and new wind drifted snow terrain not withstanding). Pools of graupel may also exist in usual terrain but I would imagine these would be increasingly difficult to trigger unless another significant load (cornice fall, another avalanche, etc). Otherwise I didn't see anything in the top meter that alarmed me. Uncertainty exists around the Valentine's Day facet/crust layering on east/southeast up high, but this - at least at many mid/low elevation areas - is well protected by a supportable or mostly supportable mf crust on the surface.

Mostly I went looking to see about the snow surfaces ahead of tonight's storm.
  • On solar aspects, I did not see any new radiation recrystallization facets above a crust. I would imagine the new snow coming in warm might bond favorably to warm and corrugated melt freeze crusts and/or damp snow.
  • On polar aspects, it appears that very warm temperatures, cloud cover and wind has eroded, baked, or softened (rounded) the rough edges of the weak snow at the surface. The 3-4mm surface hoar has "baked in" via melt/freeze and/or is now "laying over". In general, "laying over" surface hoar is not as collapsible as it is when it is standing up and not as much of an issue. At least this is my experience.
What I would take this to mean is that the snow surfaces are not quite as weak (and trending favorably) as they might have been under clear and cold skies*. The new snow may not bond as poorly as previously expected. Still, this is only one consideration and may be only academic if snowfall rates go through the roof and the wind transports the new snow into unstable slabs as expected.
*The fine print: Let's not outsmart ourselves. This is what I would be looking for tomorrow morning as guidance but not gospel. Field testing the hypothesis is a must. As longtime Canadian avalanche researcher Bruce Jamieson told me - Remember, a rounding facet is still a facet. Don't forget.
Nature shot -
Today's Observed Danger Rating
Tomorrows Estimated Danger Rating