J.Spin

Ahh, yes, thank you. That’s the term I was looking for.

If we wanted to use it, I’m sure there’s a very pertinent audio reference that could be applied here.

Event totals: 0.1” Snow/0.01” L.E. I thought this would be the end of our current run of days with snowfall, but I was surprised to discover it snowing this morning at observations time. The snow continued after observations time as well, so it looks like we’ll have another couple of entries for this streak. There’s really no notable system around, and the main discussion in the BTV NWS AFD is about the inversion, so this snow is going to be attributed to the moisture associated with the current inversion event. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.1 inches New Liquid: 0.01 inches Snow/Water Ratio: 10.0 Snow Density: 10.0% H2O Temperature: 23.4 F Sky: Light Snow (1 mm flakes) Snow at the stake: 6.5 inches

Yeah, that’s sort of the result of the first couple of salvos of snow that some of the models show for this coming week. If you look at the latest run of the GFS, you can basically see four snow events now, one each day starting on Tuesday, with each subsequent one becoming more substantial. It won’t necessarily play out exactly like that of course, but stepping through the GFS frames for this coming week has definitely got that sort of look… I can’t quite recall the term at the moment, but I know I’ve seen an image posted frequently here in the NNE thread to describe it. I’m sure the term will come to me at some point.

I was last out at the mountain on Sunday, and although we’ve only had a few additional inches of snow since then, it seemed like today was a good day to head on up for a tour and check out the conditions. I didn’t check out any of the manmade or lift-served terrain today, but I started my tour on the Bolton Valley Nordic and Backcountry Network and then connected over to the Wilderness area. The Colorado-esque weather regime over the past few days has definitely been outstanding with respect to snow preservation. In areas that haven’t been skied, all the recent snows are just sitting there in the form of midwinter powder, and I found depths of generally 6-12” at the 2,000’ elevation and 8-12” up around 2,700’, which was as high as I went on my tour. I’d say the main issue is still the base below that snow. It’s quite variable, and down at 2,000’ in the Village elevations there’s nothing at all below the powder in unprotected areas. In the higher elevations the base is a bit less variable, but there’s still nowhere near enough base for steep terrain. What I saw that impressed me most on today’s tour was the state of skier-packed natural terrain. Areas like Lower Turnpike, Telemark Practice Slope, Bryant Trail, and Nordic trails like World Cup (some of these may have been machine-packed) were in very good to excellent shape. Presumably, these areas of packed snow held up well against the warmth around Christmas, and now the additional snows of the past week or two have reinforced that base. Lower Turnpike had nearly perfect coverage, and all this packed terrain is going to make for some excellent powder skiing when the next storms come. All in all, though, you could definitely feel that winter has settled in for the mountains, even if the snowpack/base is on the low side. The water bards I encountered today were all sufficiently frozen, although most of them are still visible and require a bit of navigation. A few shots from today:

Yeah, can’t blame you for wanting to experience some of that cold NNE weather to get a feel for it in your new spot. But as PF has been showing, this is why when folks are pining for these patterns with dumps of super cold temperatures in the Northeast in midwinter, we’re not necessarily jumping for joy. For the most part, it’s not needed. Sure, it can freeze up bodies of water and the snow preservation is good, but it often means we get to sit in dry, frigid, arctic air and freeze our butts off on the slopes in subzero temperatures while the storm track is pushed southward out of the area. “Oh, you mean we get the privilege of having dangerous subzero temperatures in the mountains and no storms to refresh the ski surfaces? Wow, what a deal!” Obviously there are various degrees to which this happens, but you get the idea. Up here, getting moisture is the key in midwinter. Aside from being warm-sectored from a storm to our immediate west, or some highly anomalous pattern, the midwinter temperatures up here take care of themselves. The current stretch with these well above normal temperatures sort of testifies to that. Systems are still in the queue for next week though, with potential impulses on Tue/Wed, Thurs, and Friday, depending on which model you look at. It’s still a bit far out to start getting into amounts, but it looks like we’re talking northern stream stuff that is pretty reliable once we get within a few days. The thoughts from the BTV NWS seem right in line with what I’m seeing, with chances increasing as the week progresses: .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 302 AM EST Saturday...Increasing chances for precipitation as we head through the week owing to a series of upper shortwaves that will cross the region. As is typical with these sort of scenarios, there`s a fair amount of disagreement in the specifics of these systems, not only model to model but also run to run. That being said, it still looks like the best chances for widespread precipitation will be late in the week with a weak clipper system moving in from Ontario, followed by the upper trough digging to our west. This latter feature will also result in a slight warming trend through the week; hence the precipitation would likely be a rain/snow mix in the valleys and snow in the mountains.

Those are my exact sentiments - these temperatures have been awesome. And it was around 20 F when I was out during the day yesterday and it definitely felt cold. It was a reasonable cold though, I didn't even contemplate putting on a layer over my pants, and it was still fine. I'm pretty sure a high temperature like that is below average though, even for around here in January.

I’m sure that here in VT, carpooling (with masks) has to be allowed to a certain degree because some people have no other means to get to work, get to the doctor, etc., but I don’t think the state regulations encourage being in an enclosed space (e.g. vehicle) with someone from outside your household, do they? I’m pretty sure you can’t eat meals with people from outside your household yet either here, but the rules could be different in different states.

I was just talking about that very topic with a colleague at work yesterday, and suspect those are the sentiments of a lot of folks around here. I actually expressed similar thoughts in my Bolton Valley report from Sunday: “…folks aren’t yet using all the acreage of tree skiing; the trees were generally untouched because people know that it’s still just a bit too thin in there for the skiing to be practical. I saw an occasional track of people who had headed into the trees, but you could tell they weren’t quite ready. If we get one more good snowstorm with an inch of liquid, then the low-angle trees will be in play.” “We still need a solid synoptic storm with an inch of liquid equivalent (or something similar from a series of smaller systems) to really get the base depths to more respectable levels, but Winter Storm John was a godsend to at least get a bit of base down and have some snow to see us through the next week.” Based on years of observations around here in the Northern Greens, I typically use the point of reaching 24” at the Mt. Mansfield Stake as a rough marker of when initial tree skiing starts in the local mountains. This would be for those lower-angle, well-manicured glades such as the Sunrise Glades and Birch Glades in the Mountain Chapel area at Stowe, or Wilderness Woods at Bolton Valley, etc. Obviously the depth at which tree skiing becomes practical can vary based on the density of the snow making up that 24” depth at the stake, and the snowpack depth will typically be a bit lower down at elevations of 2,000’ or 3,000’, but the 24” number seems to work pretty well, and it certainly works for a comparative benchmark. With the stake snowpack currently at 15”, we really are just about one large storm, or a few smaller ones, away from hitting that point. People may not remember it, but it’s interesting to note that last year was actually a relatively late start to getting the trees going based on the 24” assessment. Although we had a very early start to the continuous winter snowpack around here in the mountain valleys (November 8th), it wasn’t until January 2nd, that the Mt. Mansfield Stake finally hit that 24” mark. I’d certainly forgotten it was that late, and that’s actually more than 1 S.D. (actually 1.06 σ) behind the mean date of Dec 13th. Here’s the updated plot of the date for reaching the 24” depth using all the Mt. Mansfield stake date since 1954. You can see last season’s date of reaching 24” indicated by the red star, sitting just to the right of the 1 S.D. line in the plot. As PF has noted for this season, we are getting out into relatively rarefied territory with respect to the Mt. Mansfield snowpack depth at this point. If you look to the far right of the plot above, you’ll see that there are just a handful of seasons where the 24” depth has been achieved this late. Next week certainly has some potential for snow, but as of today, we’re already sitting at 1.37 σ) behind that mean date of Dec 13th, so we’re into the bottom 10% of seasons. It’s funny that both in terms of snowfall and snowpack depth, we’re really close to average here in the mountain valleys, but this has been one of those seasons thus far where the mountains are seeing much larger deviations, certainly when it comes to snowpack depth.

Event totals: 0.3” Snow/Trace L.E. Details from the 12:00 P.M. Waterbury observations: New Snow: 0.2 inches New Liquid: Trace Temperature: 23.5 F Sky: Light Snow (2-6 mm flakes) Snow at the stake: 7.0 inches

I’d been feeling like we’ve had quite a run of days with snow, but your comment made me check on my CoCoRaHS data. Indeed, the last day in which we didn’t have at least a trace of new snow at our site was all way back on Christmas, so that’s 14 days in a row. And today’s snow will actually add a 15th day to this run. Some of the least snowy periods around here are when we get under that cold, dry, arctic air with clear skies. The air is just so cold that it can’t hold much moisture at that point. You can still get accumulations from that arctic diamond dust during those periods, but that doesn’t produce the type of flakes we’re seeing today. This weekend it looks like it might actually clear out to a degree that would end the streak of snowy days, but the models suggest we’ll be back into some potential systems next week. Some models have snow signaled as early as Monday night/Tuesday, but most have something by midweek, and the chances just seem to increase as the week progresses. PF actually did a great job making the point about the models not catching all the potential snow in a post that he made back on (coincidentally) Christmas Day. The projected snow map showed a maximum of 1-6” of snow along the spine through the 16-day period ending on January 10th. Reinforcing the point, the top end of that snowfall projection was esentially surpassed the very next day. Now we’re almost at the end of that period, and we’ve had six distinct storms/events, three times the maximum projected snowfall down here in the valley, and I’m sure even more at elevation. The models just can’t catch all the multitude of systems that are going to affect these types of mountain climates, especially at those long lead times.

It sounds like you guys definitely got into the moisture up there. This snow certainly wasn’t expected around my area today, and we’ve got a much steadier light snow out there now. This type of snow is often something that doesn’t show up on the radar because it’s low level and not caught by the beam, but there is a visible pulse coming in from the NNW:

Thanks so much for these observations PF. I had already made my decision on the source of this snowfall for my storm records based on the BTV NWS AFD (although I had to make a best guess because they didn’t really mention it at all). Your observations from up high and down in the valley confirmed it though – today’s snow definitely comes from moisture under the inversion layer vs. persistent moisture from that system lingering in eastern Canada.

Event totals: 0.1”/Trace L.E. With the snow accumulation I saw on the boards this morning, it was tough trying to figure out if it was still attributed to the cutoff circulation over eastern Canada, or something else. Based on the BTV NWS forecast discussion though, they really speak of the moisture trapped under the inversion layer, and dry air aloft, so this is being attributed to the inversion layer moisture barring some changes in the discussion. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.1 inches New Liquid: Trace Temperature: 19.8 F Sky: Light Snow (1-2 mm flakes) Snow at the stake: 7.0 inches

Neat! That video is apparently from Yuzawa, Japan, and if I’m reading the climate data correctly, it looks like the seasonal snowfall average is 466” there.

Event totals: 3.1” Snow/0.23” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.2 inches New Liquid: 0.01 inches Snow/Water Ratio: 20.0 Snow Density: 5.0% H2O Temperature: 24.8 F Sky: Partly Cloudy Snow at the stake: 7.5 inches

I can never tell quite what’s in the flow up by you guys on our BTV radar, but with your webcam I can at least get a snapshot current view and see that there are flakes flying. Anyway, we just got hit with a quick burst here, and I see that the easterly/southeasterly flow has some upstream moisture, so it’s definitely something to watch for. This is where the mountains do their thing with respect to promoting flakes if there’s at least a bit of moisture around.

We’ve got potential snow from the easterly flow through midweek from the current storm, and then some models even show potential northerly/northwesterly flow over the weekend as that storm pulls more to the north into Newfoundland. After that it looks like a more typical bread and butter-style flow sets up in the beginning to middle of next week. Most models show northern stream shortwaves and the lakes starting to fire up at that point. That could change of course, but as you know, that sort of flow is typically much more reliable than the erratic processes of phasing coastal systems. The long term in the BTV NWS AFD does actually mention that anticipated change away from the coastal low pattern to a more zonal flow: Area Forecast Discussion National Weather Service Burlington VT 916 AM EST Tue Jan 5 2021 LONG TERM /FRIDAY THROUGH MONDAY/... As of 245 AM EST Tuesday...A strong omega block centered over the northern Atlantic Ocean will continue through the weekend before flow begins to become more zonal as the blocking pattern finally deteriorates. Prior to this, a polar low will drop out of Canada into New England with a burst of colder air to follow. Unfortunately, the lack of moisture will likely inhibit the potential for any snow showers as all signs point to a completely unsaturated snow growth layer. Temperatures following this polar low will drop closer to seasonal normals but as has been the trend this winter, temperatures should remain on the warmer side of normal. Temperatures will rebound a bit as we head into the beginning of next week but the potential for any storm systems within the next 7 days appears next to nothing. With the AO and NAO both trending toward neutral, we are getting out of the coastal low pattern seen mid-December through early January. I know some folks want January cold to freeze up the waters, but I’m definitely partial to this sort of pattern with clouds and at least small chances for refreshers vs. sitting under arctic high pressure with numbing temperatures and no chances for anything. Below average temperatures around here in January are just so brutal. They would probably help with respect to snowmaking based on what PF said in the ski thread, but I know they’re at least making snow in the current regime. Looking at my data, we’re just over a third of the way through a typical snowfall season and we’re on our 21st system with accumulation, so that’s actually a pretty solid pace for storm activity. We haven’t had that insane mix of continuous bread and butter and larger all-snow systems that sometimes happens, but we’d likely be ahead of average on snowfall if that had been going on. What we’ve had has at least let us keep up an average pace for snowfall, it just loses a bit of its “punch” when snowpack preservation has been poor until recently. This is a bit of a lull in our storm pace, but I know you’re enjoying the fact that you’ve got snow on the ground and it shouldn’t be going anywhere in the immediate future. The winter vibe at your NH place is probably much different at the moment than it would be in MD.

Event totals: 2.9” Snow/0.22” L.E. We picked up another 0.4” of snow overnight, which was somewhat unexpected, but the forecasts/discussions did indicate the chances for this type of snow during the first part of this week. The current BTV NWS discussion suggests that this precipitation is still related to the same storm we’ve been dealing with for the past couple of days, which is now south of Nova Scotia, and the radar (below) clearly shows that moisture coming from the east, so I’m rolling these numbers in with the current system. Area Forecast Discussion National Weather Service Burlington VT 635 AM EST Tue Jan 5 2021 NEAR TERM /THROUGH WEDNESDAY/... As of 635 AM EST Tuesday...Mainly uneventful weather expected over the next 42 hours despite plenty of clouds. Upper level trough extending west- northwest from offshore low pressure south of Yarmouth, NS continues to pull some mid-level moisture westward back into northern New England/nrn NY this morning and expect this trend to continue into tonight. Therefore, will continue with slight to lower chances of flurries/light snow shower activity across mainly northern counties during this period as forcing will remain weak. By Wednesday the offshore low and aforementioned upper trough begin to pull east fostering a slight uptick in the low level pressure gradient and northwesterly surface winds. This may allow some partial clearing in the Champlain and CT River Valleys toward afternoon. Temperatures to remain slightly above seasonal norms in the upper 20s to mid-30s. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.4 inches New Liquid: 0.03 inches Snow/Water Ratio: 13.3 Snow Density: 7.5% H2O Temperature: 30.0 F Sky: Cloudy Snow at the stake: 7.5 inches

I’d been meaning to check on where we are at our site, and had a chance to look at the numbers today. Snowfall: The combination of a strong November and weak December came together to really keep us right around average on cumulative seasonal snowfall over the past couple of weeks. We’re just slightly ahead of average pace as of today with 55.7” on the season, vs. a 54.6” average to this date. This season will presumably fall off the average pace a bit if this week is slow with respect to snowfall; we need 1-2”/day this time of year to stay up with the mean. Snowpack depth: Today’s snowpack depth at our stake is 9.0”, which is actually quite close to the mean of 9.7” for this date. SDD: Current snowfall for the season and current snowpack depth suggest that things are pretty typical, and indeed they are in those respects, but SDD incorporates a bit more of the season’s history with respect to snow preservation. SDD to date at our site is 106.5 inch-days, which is less than half the 243.5 inch-days average for this date. So, while snowfall and current snowpack depth are typical, it’s definitely been a below average season in terms of snow preservation thus far.

December Totals Accumulating Storms: 11 Snowfall: 23.4” Liquid Equivalent: 4.69” SDD: 54.0 Calendar Year Liquid: 50.64” I’ve had a chance to put together the December snow numbers for our site, and some notes about them are below: · Snowfall was definitely on the lean side for December this season. It’s interesting to note that we picked up the same amount of snow in December as we did in November, which speaks to a solid November and a poor December. This December’s snowfall was actually the third lowest in my 15 seasons worth of records; only 2006-2007 and 2015-2016 were lower. · Also of note is that SDD were quite low at 54.0 inch-days, whereas the mean is 180.8 inch-days.

Thanks PF, that’s really insightful stuff that the average resort visitor is not going to be aware of. I always knew that snowmaking was much more efficient down at those lower temperatures (to a point, since I know you’ve said that are issues when it gets too cold), but I had no idea the temperature threshold for decent efficiency (mid 20s F) was so low. Obviously wet bulb temperatures etc. play into that too, but wow, I figured the big efficiency issues didn’t start until you got to around 32 F and above. As a skier, I’ve been loving these moderate temperatures we’ve had thus far in December and January – cold enough to get snow and hold it (barring the storms where we get into the warm sector significantly of course), but not so cold that we’re freezing our butts off out there. I look at the forecast and see mountain high temperatures in the 20s to near 30 F and think, “sweet!” – I had no idea that the departures were representing such a challenge for snowmaking.

Event totals: 2.5” Snow/0.19” L.E. Since it was Monday, I also cored the snowpack at observations time this morning and found 0.84” of liquid. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.3 inches New Liquid: 0.01 inches Snow/Water Ratio: 30.0 Snow Density: 3.3% H2O Temperature: 28.4 F Sky: Flurries Snow at the stake: 9.0 inches