Bolton Valley, VT 12/31/2010

[J.Spin]

Bolton Valley, VT 31DEC2010

On Friday our friend Dave came up from Boston for a skiing visit, arriving in the late morning with his dogs. Like Thursday, we headed up to the mountain around midday, and the found that the trend of moderating temperatures had continued as suggested by the forecasts; we’d seen high temperatures in the low 30s F on Thursday, and Friday’s temperatures topped out around 40 F. The weather was again often sunny, but not quite as brilliantly sunny as Thursday had been.

We’d never left the Timberline area during our Thursday outing, but I’d received an email from Stephen that evening telling me that the mountain had fired up the Wilderness Lift. We decided that we’d head over for our first lift-served Wilderness turns of the season, and Dave and I rode up with one of the ski patrol who said that getting in our turns over there as soon as possible was a good idea. With the temperatures remaining warm through Saturday/Sunday, she said that they might need to shut the lift back down by the weekend. We stopped in at the main base so I could grab a ticket for Dave, and while I was in the lodge, he and the boys dropped down on the snow and enjoyed the sun and warm temperatures.

With all the lifts running, we found that lift queues were either nonexistent or pretty inconsequential, which was nice considering that it was a holiday week. We did a few runs on the main mountain with a couple of nice ones off of Wilderness, and then grabbed some waffles at the Waffle Cabin before heading back to Timberline to finish off the day.

In terms of conditions, the snow had transitioned right from mid winter on Thursday, to spring like on Friday. Off piste, the powder had become mushy, so we spent our time on the marked runs. The on piste snow was actually quite good, as it wasn’t too sticky and we even found some areas of corn forming where manmade snow, traffic, and sunlight had come together appropriately. All the terrain that had been open on Thursday appeared to be open on Friday, but with the softer snow, thin areas with traffic were starting to reveal ground on some natural snow trails. We had a really fun run down Twice As Nice with the soft moguls, but we were starting to see patches of poor coverage that needed to be dodged. It was nice to have the reprieve from more typical temperatures for New Year’s Eve, and getting in some spring-style skiing was nice, but we also wouldn’t have minded the two plus feet of Champlain Powder™ that fell at this point last season.

J.Spin

 

[Tony Crocker]

I would be interested in JSpin's take on why 40F temperatures in Vermont in the dead of winter can cause:

snow had transitioned right from mid winter on Thursday, to spring like on Friday. Off piste, the powder had become mushy

I'm guessing Bolton has some north exposures, and even east and west exposures are surely shaded in the woods at this time of year. I'm sure JSpin observed when he was in Montana that this would not happen so quickly in the West until spring. My only guess is high humidity, but not so sure why that would have such a big impact. Looks like last weekend was a "C" because no more packed powder and trail counts are still only somewhat over half in northern Vermont.

 

[J.Spin]

I would be interested in JSpin's take on why 40F temperatures in Vermont in the dead of winter can cause:

snow had transitioned right from mid winter on Thursday, to spring like on Friday. Off piste, the powder had become mushy

I'm guessing Bolton has some north exposures, and even east and west exposures are surely shaded in the woods at this time of year. I'm sure JSpin observed when he was in Montana that this would not happen so quickly in the West until spring. My only guess is high humidity, but not so sure why that would have such a big impact. Looks like last weekend was a "C" because no more packed powder and trail counts are still only somewhat over half in northern Vermont.

I’m sure that higher humidity exacerbates the issue, but even in Montana I wouldn’t expect that kind of dry, fluffy powder to survive extended periods of 40 F temperatures. The powder has so much air in it, that warm air permeates into it easily and melts crystals much deeper into the snowpack. With minimal substance in that low density area of the snowpack, everything above the consolidated base can turn to that non-supportive mush. Sufficiently dense, or packed snow, is much more resistant to getting mushy, presumably because the warm air doesn’t penetrate it as easily. For instance, packed surfaces such as the alpine runs we skied on Friday or the Bryant Trail we visited on Saturday, didn’t turn to mush like the powder did. Dry air seems to help mitigate the formation of the mush because if the humidity in the air is low enough, the liquid from crystals that melt can evaporate into the atmosphere. If the warming has not gone too far, the air stays dry enough, and the powder is undisturbed, the powder will actually recover sometimes. The crystals aren’t as delicate as they initially were because it’s likely some have fused together with the melting, but it can still ski pretty nicely. I think last weekend’s warmth around here was beyond that point since the temperatures got well into the 40s F, but fortunately in terms of powder turns, new snow has been falling on top of the old stuff.

 

[Tony Crocker]

I don't think fresh, unconsolidated powder would stay that way at 40F. But on shaded slopes at high altitude western areas it will usually not go through a melt/freeze, or if so very gradually.

Dry air seems to help mitigate the formation of the mush because if the humidity in the air is low enough, the liquid from crystals that melt can evaporate into the atmosphere.

Wind is very helpful to this process, as I observe at Mammoth nearly every spring. However, on the steeper north slopes it remains packed powder even without assistance from the wind, as evidenced in LCC which does not have Mammoth's chronic wind.