J.Spin

April is another one of those months with a lot of snowfall variability, and it came in a bit on the plus side this winter. Nothing has come close that the snowfall we had in April 2007, but it’s interesting to note that the past several years have shown much more consistent snowfall totals relative to the period before that really exhibited that April variability. I think of April as the spring equivalent of November when it comes to the frequency, amount, and overall tenor of snow. But as I look at the numbers and summary plots now, it’s obvious that November is much snowier; our site averages more than twice the amount of snow in November compared to April, and the number of storms is nearly double as well.

Moving into the last third of winter season, I have the March snowfall data for our site below. This past March was certainly below average in terms of snowfall, but not down there in the single digits as we’ve seen a couple of times. March shows much more variability than stalwart February, and on that note, it’s interesting to see that even March has exceeded a 55” monthly snow total in our data set, whereas February hasn’t. Despite the variability, there haven’t been any long runs of lean Marches, and on the higher end, that 2017-2019 period looks like it was a standout stretch of March snow totals.

Approved.

That winter was so outrageously anomalous in this area (snowfall at our site was 2.38 σ below the mean, statistical occurrence at 1 in 116 seasons). It’s hard to imagine how it even happened, especially around here in one of the most consistent snowfall areas in the eastern U.S. I did a quick look through my ski reports from the season, and it seems that for starters, it took forever to get going. My first day of backcountry skiing was on January 23rd, which is probably not all that late, but the snowpack at the Mt. Mansfield Stake didn’t even reach 30” until February 21st. In addition, the stake never reached even the 40” benchmark. I was wondering if it was some powerful combination of being both warm and dry. It was somewhat dry (October through May precipitation was about 5 to 6 inches below average at our site) so that likely contributed to part of it, but after reading through some of my reports, it sounds like “warm” was also a theme, and may have been the larger contributor to the overall result. Thank god we at least didn’t know beforehand that such a low snowfall winter was coming – I’m not sure how it would have affected the psyche of everyone involved in the various snow sports industries if we knew ahead of time what everyone would have to go through.

February is next in the monthly snowfall chronology, and it was a solid contributor this past season. At face value, I wouldn’t consider this past February’s snowfall anything more than roughly average, but as I’ve been seeing with these plots, actually putting together the visual is a nice way to get a feel for trends. The plot reveals that although 47.2” is nothing remarkable, it’s actually the fourth highest February in my records. Even before plotting the data, I knew that February was the king of consistency at our site among the various snowfall months, so that probably puts its reliability way up there for an area that already has a relatively high consistency in snowfall. The only February in the plot that really sticks out as much of a dud is the one from the highly anomalous ’15-‘16 season – all the other entries look quite decent. Consistency usually plays both ways of course, and I hadn’t noticed the lack of outstanding Februarys until making this plot. In 15 seasons worth of data now, there’s no February getting anywhere near the 70” range like instances I’ve seen for December and January. There hasn’t even been a February approaching 60”, and the month has yet to hit even a modest 55” total here in that entire period of record. I’d say that current February snowfall record for our site is certainly ripe for breaking at some point, but climatologically, it’s funny to think of how an incredibly snowy month like February has thus far been capped under 55” of snow here.

Indeed, snowfall consistency seems to be a big feature of our location, and I’d say in the Northern Greens in general. It feels like the climatological aspects that impart the snowfall consistency are likely playing a significant role in pushing the annual snowfall averages above the other mountain ranges in the region as well. If I had to rank the factors promoting consistency at our site relative to other regional locales, I’d say that orographics is probably at the top of the list. On the next tier for consistency contributors I’d put effects of LES by being relatively proximal/downwind of the lakes, and being one of the windward ranges in the region. Having Clippers (vs. other types of less consistent storms) as a major part of our winter snow climate is probably in there as well. The presence of Clippers themselves shouldn’t really be much of a consistency factor relative to the rest of NNE, since everyone at a certain latitude should get in on the storm, but the performance from those Clippers is enhanced by the other factors. I think where areas off to the south and east of NVT can capitalize more on snowfall is with coastal storms. It’s not that the Northern Greens miss out on coastals/nor’easters, and in fact we can often do quite well with the synoptic portions of those systems. However, if it’s one of those more compact systems, or something farther offshore, on average, it seems like areas off to the south and east are going to get more snow/liquid from the synoptic portions of those storms. The thing is, coastal storms are already a somewhat infrequent occurrence, and on top of that they lack consistency in positioning and behavior even when they do occur. So, potentially performing marginally worse in a phenomenon that is relatively infrequent with inconsistent performance, just isn’t going to be much of a hit to snowfall averages. It’s really not likely to affect snowfall consistency much, and if anything one might want to down weight our typical coastal systems in their snowfall climate repertoire if the goal was improved snowfall consistency.

Next up in the analysis of this past season’s snowfall is January, and those data are below. This past January was at least average with respect to snowfall, and it was even a bit better than the previous season. A trend that we’ve talked about in the forum, but certainly stands out when the data are plotted, is that notable stretch of Januarys with poor snowfall from 2012 to 2018. That period contains the five least snowy Januarys in our period of record, packed into quite a short span. Prior to that stretch, the January snowfall average in our data set was similar to the other midwinter months at ~40”, but it really started to fall off during that period. In many cases, the reduced snowfall seemed to be in part due to those January outbreaks of arctic air, where the storm spigot would shut off in NNE as the intrusion of dry, cold air pushed the storm track farther south. We’ll see how January behaves around here going forward, but these past three seasons seem to have been a return to the type of snowfall we’d had before that period.

It’s probably not coincidence that those are our two wettest months as well, although it is interesting that they’re flipped with June the wettest averaging ~7” of liquid and October next with ~5¼” of liquid. Perhaps they’ll even out somewhat as the data set continues to grow.

I see our site is on there at 15.53” – we were close to 5” behind average pace at the end of May. June is the wettest month in our data set, averaging almost 7” of liquid. We’ll have to see how the rest of the month goes, but since it makes such a big contribution to the average annual precipitation, it’s an easy month to put things farther behind average pace if it’s a slow rainfall month.

Looking at the December snowfall data for our site, we can clearly see that December 2020 was below average - it was actually the third lowest in the data set. With the low snowfall, I was thinking there might be an obvious segment of the month that was devoid of new snow to account for the deficiency (I know there was that somewhat warm period around Christmas day). The daily distribution of snowfall doesn’t show that though; the snow was actually distributed fairly evenly throughout the month. There was new snow on 19 of 31 days, and the longest period without new snow was three days. Even that period near Christmas day that came to mind only represented two days (the 24th & 25th) without new snow. I can put those daily snowfall data together in a different plot at some point. Similar to the November snowfall plot, the visualization of December snowfall really highlighted a trend that I hadn’t noticed. It was somewhat startling to see that we really haven’t had a strong December in our area in eight seasons. I actually think the long-term average for December snowfall at our site is around 40 inches, so even December 2017 was essentially average. That means one has to go all the way back to 2012 since we’ve really seen a solid December. After that notable stretch, we’re probably due for a rebound at some point.

Looking at the November monthly snowfall numbers from our data set, we can see where November ’20-‘21 stacks up. Indeed it was a fairly strong November overall, and with back-to-back storms bringing over a foot of new snow on the 1st and 2nd of the month, it got things off to a very early start that kept the cumulative snowfall ahead of average and helped buffer season snowfall through the relatively slow December. One thing that I hadn’t really noticed until putting the data into graphical form was what a solid run of Novembers we’ve had as of late. The past five Novembers have all been essentially at or above average, and that cluster definitely stands out on the plot.

My previous plot provided the average snowfall for each month to allow comparison to the ’20-‘21 totals, but we can also look at a month across the data set to see where ’20-‘21 sits among the distribution of data. October this season was about as average as it gets at our site for snowfall – it fits right in there among the high and low months, and it actually represents the median value for the data set.

That March value must be quite an outlier for a NNE location. March can certainly show a lot more variability in snowfall relative to DJF in my experience, and snowless/nearly snowless versions can happen, but this far north it’s only a certain combination of warmth and/or dryness that can get the month to come in that low. That’s a good topic though; I’ll start looking at the monthly snowfall comparisons in my data set next.

The next look at the ’20-‘21 season snowfall data is by month, with the plot below showing this past season’s monthly snow totals compared to the ’06-’21 averages (white diamonds) in my data set. There weren’t any really outstanding months this season, but November was solid. It was up there among the top five in my data set, although more than 10 inches behind the strong ’18-‘19 November we just had a couple seasons ago. The below average months are quickly evident, and they were December and March. Each was more than 10 inches below the mean snowfall value, and they obviously marked a couple of the major slow periods shown in the cumulative snowfall plot.

On the topic of snowfall for the 2020-2021 winter season, the next look is at cumulative snowfall, giving a sense of the points in the season at our site where it was ahead of, or behind, average pace. The first plot shows actual snowfall numbers (blue) relative to average (white), and the strong start in early November is very evident. That positive departure was gradually lost through the relatively slow December into the middle of January period before it picked back up from mid-January through mid-March. Then the pace of snowfall slowed down again, briefly getting behind average pace in mid-April before finally recovering at the end of the season. The second plot simply shows the deviation from average cumulative snowfall in inches, but more easily lets one view where the seasons was ahead of, or behind, average snowfall pace. That strong start in early November really jumps out here as well. The more dramatic “surprise” that I think this plot shows well is that despite a season with a relatively lackluster tenor, the vast majority of the season in this immediate area was ahead of average pace on snowfall. It’s really just that notable January dip where the pace fell of substantially, and even there it was still less than 10 inches behind average. The fact that two big chunks of the season (November through mid-January, and mid-February through mid-April) were periods where snowfall was simply losing pace vs. average (note the negative slopes in these parts of the plot) probably played into the potentially reduced perception of the season despite still being ahead of average snowfall pace.

Thanks for the data - I put together the graphics for the difference from mean snowfall at our sites by season, and with disparate averages, using percentage to normalize seemed like the best way to facilitate the comparison. As you noted, ’14-‘15 represented a somewhat substantial directional difference, with ’13-‘14 right next to it being a more muted version. And historically during this period of record, that’s really been it for directional differences aside from ‘06-‘07, but that season’s data are so tight to the means that the differences are really inconsequential. The rest of the differences have just been magnitude. The data certain speak to the general NNE trends in seasonal snowfall we often see, with that horrendous ’15-‘16 season being an extreme, but effective, example. The ’15-‘16 season was outrageously poor with respect to snowfall (an almost unbelievable season at more than 2 S.D. below the mean here at our site). I think NNE had some of the largest deviations from average in the region that season, and even within NNE, I think NVT showed some of the largest deviations. The whole season was quite poor region wide with respect to snowfall. ..and then we have the ’20-‘21 season. It’s quite an outlier on the plot that stacks both the directionality and magnitude of difference between our two sites like nothing else in the data set. It’s not at all like ’15-‘16 that had poor snowfall region wide. Weren’t some SNE sites even above average on snowfall for the season? So to see numbers at your site in the realm of ’15-‘16 (which it certainly looks like on the plot) would seem to make the season extremely anomalous. If someone’s got access to it, or knows how to generate it, I think it would be very interesting to see the New England map for snowfall deviation from average for the ’20-‘21 season. It seems that off to the east of here was affected the most, with NH affected somewhat, and then ME affected to an even greater extent? What was it like for northern and eastern ME?

June 1st is generally when I consider the snow season complete here at our site, so I can start finalizing the numbers. Total season snowfall is the main parameter I track, so I’ll start with that. There were certainly some dry spells with respect to total snowfall, but ultimately the season ended up with 160.6” here, which is about average for my period of record. Below I’ve got the plot of how this season’s snowfall compared to the others in my data set, with the mean value for the data shown by the black dashed line.

May Totals Days with new snow: 2 Accumulating Storms: 1 Snowfall: 0.2” Liquid Equivalent: 2.92” SDD: T I’ve put together my snow and liquid numbers for May, and snowfall was typical, but total liquid was two inches shy of the mean. For the calendar year here at our site we’re at 15.05” of total liquid, which is about five inches behind normal pace, so we’re running a bit on the drier side of average.

When I was out in the yard earlier this morning, we started to get a bit of rain, but I hadn’t seen anything notable on the radar earlier. When I checked later it had the look of upslope showers with a northwest flow, which I don’t think we’ve seen here at our site in at least a couple of weeks. It’s still relative mild out there right now, but that flow definitely gives it a bit of an autumnal feel. On a somewhat related note, I see that the BTV NWS has also put out a Frost Advisory here for tonight, so folks in the area might need to cover up if they’ve put any early plants out.

Thanks for the update – I can definitely see that the width of the available snow has contracted some since when I was there on my outing. I had time on Sunday, so I headed back out for a hike and some more turns. Based on what I’d seen on Spruce on my last outing, as well as the views across to Mansfield at that point, I decided it was time to check out something by the Mountain Triple. There’s some easy access snow right down to the base over there, and that fit the time I had. As I walked along past the Triple, I surveyed the snow situation and headed toward Lower Standard, which seemed to have the best coverage. That area makes for a pleasant stroll because it’s generally quite grassy with modest pitches. Somebody had built the shape of a heart out of rocks on the ground near the ropes course, so that was kind of a nice accent to the area. The snow on Lower Standard is definitely more broken up than what it was a week earlier, and there are a couple of gaps near the bottom that are really best walked vs. trying to skip across on your skis. Sunday was the day we had those thunderstorms around, and as usual, there were some great views surrounding the resort and toward the Notch as the peaks worked their magic and forced the clouds around. While I was hiking I started to hear thunder to the east and northeast, off past Spruce Peak and over toward Madonna and Sterling. Eventually I started to see some tendrils of virga over there, and the thunder was becoming more expansive. I was just getting up toward the Crossover elevation, which was about where I was going to stop anyway because the snow petered out there, but the timing seemed good with the thunder building. I started seeing the first visible flashes from lightning just as I was getting back to the car, and the first drops of rain began to fall, so that worked out. I would have stayed around for some lightning photography over toward the Notch, but none if was producing visible bolts, it all seemed to be well up in the clouds or too distant. A few shots from the outing:

We had a few sprinkles here at the house about an hour ago, but the main moisture definitely seems to be off to east as your radar image shows.

I saw your Spruce post and headed up on Sunday for a hike and some skiing when I had time to get out for exercise. I probably wouldn’t have even had Spruce Peak in the mix of top spots to head for turns if I hadn’t seen how much snow was still there, but it was obvious from your report that there was plenty. It’s certainly not continuous top-to-bottom of course, but there’s several hundred verts worth of nice turns with deep base as you showed. The snowpack there is starting to get a bit sun cupped, but it’s nothing that really hurts the experience yet at this point, unless perhaps you were to stray the extreme edges where the snow has taken a bigger hit and there’s been no skier traffic. Even if natural snowpack on Mansfield is still below average for this time of year, I have to think the coverage there on south-facing Spruce had got be at least typical for this far into May. From the view across the resort, I could see that the usual spots like Nosedive and some of those areas around the Mountain Triple still have some decent coverage, so it would be fun to mix it up with something over there next. That Main Street snow has some very deep areas, but it’s just getting a bit too broken up into segments that one eventually has to make the call to go with something with a bit more continuity for efficiency and longer flow of turns on the descent. It is always fun this time of year getting to see which parts of the resort are holding the snow best for those late season turns. It’s different each season depending on the combination of where Mother Nature deposited snow and where the guns were blowing when temperatures were optimal as you noted earlier. A few shots from my Spruce outing:

April Totals Days with new snow: 10 Accumulating Storms: 3 Snowfall: 10.7” Liquid Equivalent: 4.35” SDD: 9.0 I’ve put together my numbers for April, and it actually came in pretty average for most parameters except for SDD, which was roughly an order of magnitude below where it usually is, due to the early warmth in March. The total liquid for this April did end up about a half inch below average, but there was an additional 1.34” that fell on the 30th and gets rolled into the May numbers. That creates a stretch of close to 6” in a month though, which is a decent run of liquid.