J.Spin

Event totals: 1.0” Snow/0.07” L.E. We didn’t pick up any additional snow beyond what accumulated yesterday evening, so the above totals should be the final numbers for this event. 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: 27.9 F Sky: Mostly Cloudy Snow at the stake: 4.5 inches

Event totals: 0.8” Snow/0.06” L.E. We had radar echoes overhead for quite a while this afternoon here at our site, but it took a while for snow to actually present itself visually, presumably due to required moistening in the atmosphere. Once it did get going, the snowfall rate was pretty heavy there for a bit, with flakes up to ¾” with a mix of other flake sizes. As of the 6:00 P.M. observations time, the snowfall rate had tapered back to something lighter however. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.8 inches New Liquid: 0.06 inches Snow/Water Ratio: 13.3 Snow Density: 7.5% H2O Temperature: 26.2 F Sky: Light Snow (1 to 4 mm flakes) Snow at the stake: 4.5 inches

Snow just started falling here in Waterbury.

How a system like that one is going to play out for someone in your location is often night and day compared to what happens along the coast of SNE; for a spot like Jay Peak, we’re not even talking in the realm of miracles for a decent outcome. It’s essentially the counterpoint to what went on during Winter Storm Gail in the Jay Peak area – while that type of an event is sort of a one-off/occasional thing, the look of the next week is more of a typical winter reality result. There are actually four potential snow events in the next week though (today, Tue/Wed, Fri, and Sat/Sun), and that’s a pretty respectable pace, even for the Northern Greens.

I’ve seen that effect, and it’s very cool. I was also going to comment that there could be some real diamond dust out there too – we had some yesterday, and I just hopped on now to comment that we’ve got a bit falling this morning as well.

I added some of the relevant text from that discussion above – and you’ll see at the end that I was hoping you would weigh in. Indeed, it’s got to be exactly the right combination of very casual skier who doesn’t ski frequently enough to really pay attention to ski resort snow reports and doesn’t really follow winter weather enough to know much about what happens with respect to regional snowfall outside of the large, publicized storms. The topic even coming up in conversation is going to be limited though, because the type of person with that perception is just not typically even going to be talking about the nuances of which parts of VT get the most snow. I know I’ve encountered this perception, and can recall a specific example in a discussion at the First Tracks ski forum, but maybe it’s not as common as I thought if you’ve never encountered it.

I put together the north to south listing of available snowfall totals from the Vermont ski areas for Winter Storm Gail. The data show the trend of snowfall peaking around Okemo, and falling off to the north and south. The totals tapered off very quickly north of the Pico/Killington area, and nothing new was reported in the far northern part of the state by either Jay Peak or Burke. The relative accumulations aren’t perfectly reversed relative to more typical events, since Mount Snow isn’t reporting the highest total, but this could easily be one of those events from which casual observers in the big cities get the impression that the Southern Vermont Ski Areas have the highest annual snowfall averages. As we talked about in the ski thread, when the big coastal cities are affected with snow from a substantial coastal storm such that it gets a lot of publicity, it’s typically those ski areas down south that have higher accumulations. This is just the theory mind you, but we know the perception comes from somewhere, and that might explain it. Jay Peak: 0” Burke: 0” Smuggler’s Notch: 3” Stowe: 3” Bolton Valley: 4” Mad River Glen: 6” Sugarbush: 4” Pico: 25” Killington: 25” Okemo: 35” Bromley: 33” Magic Mountain: 30” Stratton: 24” Mount Snow: 26”

I wasn’t expecting to ski this storm at all, and hadn’t even been paying attention to it until Phin popped into the thread and gave us a heads up. But it definitely put down some liquid equivalent, even this far north. When I made noon observations today and saw that we’d picked up almost a half an inch of liquid equivalent by that point, I figured it was worth a quick tour to see how conditions were faring up at Bolton. They’ve got the elevation, but they’re also a few miles farther to the northwest of our site, so accumulations I found at 2,000’ in the Village were 4-5”, roughly the same as what we picked up here at the house. I’m not sure how low in elevation it goes, but there was still decent base snow left at 2,000’, so low-angle powder turns were quite smooth and bottomless on fat skis with the L.E. that just fell. Snowfall has been in a bit of a lull in the past few days, but the pattern looks like it’s picking up in the coming week, with potentially three systems that could bring snow. The BTV NWS isn’t saying too much about that Sunday through Wednesday period at this point, but it certainly looks like some bread and butter potential for the mountains. Even the usual modest amounts could be great atop the snow from this recent system.

Event totals: 4.9” Snow/0.50” L.E. I must have been up at the mountain when the storm finished up here, but the top half inch or so of accumulation from the most recent round of snow contained notably larger dendrites with a much more impressive ability to coruscate light compared to the small flakes from much of the storm. The last vestiges of snowfall have definitely cleared out to partly cloudy skies, so I’d say the above totals are the final numbers here for Winter Storm Gail. As the models have been showing, there really isn’t much lingering upslope on the back side of this system, probably due to the way it’s pulling quickly off to the east and not northward into the Maritimes. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.8 inches New Liquid: 0.05 inches Snow/Water Ratio: 16.0 Snow Density: 6.3% H2O Temperature: 11.7 F Sky: Partly Cloudy Snow at the stake: 5.0 inches

That’s interesting, it looks like they’re rounding most (but not all?) of the CoCoRaHS observations to the nearest half inch? I reported 1.9” of accumulation at my 6:00 A.M. observations, so it’s funny to see 2.0” listed for this site.

Event totals: 4.1” Snow/0.45” L.E. The density of this morning’s snowfall was quite similar to what we picked up during the overnight period, but the few bouts of larger flakes we had seemed to drop it down just a bit. Details from the 12:00 P.M. Waterbury observations: New Snow: 2.2 inches New Liquid: 0.23 inches Snow/Water Ratio: 9.6 Snow Density: 10.5% H2O Temperature: 19.4 F Sky: Snow (1 to 3 mm flakes) Snow at the stake: 4.0 inches

Event totals: 1.9” Snow/0.22” L.E. I don’t know exactly what time the snow began here at our location, but the last time I’d looked outside before heading off to bed was around midnight, so it was some point after that. The snow during this morning’s observations was falling quite steadily, and both the snow falling and the snow stacks on the boards had that synoptic look. Measuring the accumulation was very easy due to the extremely flat and even stack made of relatively small crystals. There was a lot of moisture in just the couple inches of accumulation, and indeed there’s a really good shot of liquid equivalent in there with snow density of 11-12% H2O. Details from the 6:00 A.M. Waterbury observations: New Snow: 1.9 inches New Liquid: 0.22 inches Snow/Water Ratio: 8.6 Snow Density: 11.6% H2O Temperature: 15.8 F Sky: Snow (1 to 4 mm flakes) Snow at the stake: 2.0 inches

I hadn’t even been paying attention to this next storm (Winter Storm Gail) because the general discussion I’d seen earlier suggested it was pretty much a Mid-Atlantic thing, but then Phin popped into the thread and said not to sleep on it up here. That was a timely wake up call, because it does actually look like we could even get a bit of snow this far north. I’ve got the latest BTV NWS maps for the storm below. There are Winter Storm Warnings and Winter Weather Advisories farther south in VT, and the projected accumulations map seems generally in line with the roughly 2-4” in the point forecast for our location.

I checked the BTV NWS AFD regarding the snow was saw today, and it looks like it was due to cold air advection with northwest upslope flow. With the clear and sharp cessation of the snowfall after yesterday’s cold front, it looks like today’s snow is part of a discrete event. Area Forecast Discussion National Weather Service Burlington VT 1212 PM EST Tue Dec 15 2020 NEAR TERM /THROUGH WEDNESDAY/... …Otherwise, nw upslope flw and caa has resulted in remaining moisture being squeezed out acrs the mountains, with additional clouds and a few flurries. Expect these to dissipate by noon, as moisture decreases.

Event totals: 0.5” Snow/Trace L.E. The cold front had clearly passed and the snow shut off last night after an additional 0.2”, but we just got another round of snow this morning after observations time. When I get a chance I’ll try to figure out if it goes with this event or gets rolled into its own. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.2 inches New Liquid: Trace Temperature: 23.0 F Sky: Mostly Cloudy Snow at the stake: Trace

Event totals: 0.3” Snow/Trace L.E. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.3 inches New Liquid: Trace Temperature: 32.2 F Sky: Light Snow (2 to 5 mm flakes) Snow at the stake: Trace

I haven’t seen any notably snowfall down at our elevation yet today, but it must have started up fairly recently because there’s light snow out there right now. It looks like the BTV NWS AFD has it covered well, and it definitely emphasizes the importance of orographics with respect getting some lift: Area Forecast Discussion National Weather Service Burlington VT 332 PM EST Mon Dec 14 2020 .SYNOPSIS... Snow showers will be possible through the overnight hours across the higher terrain of the Adirondacks and northern Green Mountains with minor snow accumulations possible at higher elevations. .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 330 PM EST Monday...We are beginning to see snow showers begin to blossom across the eastern coastline of Lake Ontario this afternoon ahead of an approaching polar cold front. Looking at the latest observations and satellite data, the cold front is currently situated across western Lake Ontario and will continue to push quickly eastward through the remainder of the afternoon hours into the overnight hours. Looking at some of the forecast soundings across northern New York, it still looks like the lack of lift through the snow growth layer is going to be a severe limiting factor for snow shower activity across our forecast area. The 12Z GFS/CMC/NAM model guidance shows virtually NIL frontogenesis (surface convergence) along the frontal boundary which is why the overall forcing remains sub-par. This should lead to much of the shower activity this evening and overnight to likely be orographically driven with any accumulations likely tied to the higher elevations of the Adirondacks and northern Green Mountains. Accumulations up to an inch or so will be possible across the higher terrain with little to nothing at lower elevations.

It looks like that stretch was about six days with snowfall, and it certainly had that classic feel of the typical regime we’ll get into here with constant flakes and pulses of higher intensity snowfall buried within the flow. It does feel a bit strange to not have flakes after that, but it looks like the potential is back starting today into tomorrow. The NNE mountains, and especially the Northern Greens with their relative positioning and connection to the Great Lakes, are definitely notable for the number of days you’re going to have snow in the air. There are certainly climates that get more snow, like parts of the Rockies, the Sierra, and similar high mountain places, but a lot of those climates are drier and their snow typically comes more in batches. They can go for long periods without any precipitation. To get into that 100+ days of snow a season type of climate, I think you have to look at places like coastal BC, Hokkaido, parts of Honshu, etc. There are probably various microclimate spots out there in the world that we just don’t know about, and likely some U.S./Great Lakes places do it was well, but the best combination is going to be a combination of mountains for consistent lift and a body of water for a supply of moisture. Checking my CoCoRaHS records, it looks like we’re at ~22 days with snow thus far on the season at our site.

I haven’t been in the main thread for a while, so I’ll have to check out the discussion. I do 6-hour clears when I can, and 12 or 24-hour clears fairly often as well depending on work, travel, etc. This fall I’ve been working from home a lot, so I’ve actually been able to do more 6-hour clears than usual. That disparity in clearing intervals seems to have been around a while, and it always seems to go back and forth; I asked my local CoCoRaHS representative a few years back, and he said it was fine the way I was doing mine with 6 to 24-hour clears. It’s really hard to get snapshots of snow density throughout a storm if you’re always waiting until 24 hours to clear. I guess if one wanted to do that, they could go with multiple boards, and you can leave one collecting and settling for the full 24 hours, and have others that you clear at intervals to get intermediate measurements on snow density. That’s just more work and gets confusing though vs. just clearing your board/boards and resetting everything for the next interval. As far as I know, the NWS does 6-hour clears, so if a CoCoRaHS observer doesn’t do that, then the observations aren’t as comparable between those sites. I think CoCoRaHS is perhaps pushing the 24-hour thing to simplify it for their observers; not everyone has the time or discipline to deal with 6-hour observations, running liquid analyses every six hours, etc., so if they want everything to be somewhat standard among their observers, it comes across sort of shooting for the least common denominator or something along those lines. A few other points about the 6 vs. 12 vs. 24-hour clearing intervals: 1. To some degree it’s a “who really cares” sort of thing. If someone clears more frequently and ends up with a few inches of extra accumulation, or even an extra 10% accumulation vs. clearing at the minimum frequency, what happens? Nothing. Nobody really cares. The police aren’t coming around to fine CoCoRaHS for not getting their volunteers in line, and it’s not as if any of us are attempting to calibrate snowfall for some high-level NIST standardization that’s going to affect everyone’s livelihood. It’s just a bunch of volunteers engaging in doing their best to measure a highly variable/inconsistent phenomenon. 2. Any variance in snowfall due to collection interval issue has basically got to be small potatoes compared to the inaccuracies people deal with in windy locations. 3. As long as you’re accurately collecting liquid, the snowfall thing is in many respects, moot. Liquid trumps all, and doesn’t vary with any sort of collection interval. For CoCoRaHS observers who aren’t collecting liquid with their winter snowfall measurements, they should be. That’s what CoCoRaHS really cares about much more than any snowfall numbers.

Thanks for bringing it to our attention. I was wondering why I hadn’t seen it when I flipped through the ECMWF Precipitation Type/Rate plot on pivotalweather.com, but I realize why. It just looks like the northern extent of whatever was passing by to the south of us, and I didn’t think it would even represent anything in terms of accumulation (I don’t find the shading scheme they use there for precipitation very helpful, so it’s hard to know if it means anything unless it’s darker, or you dive into it to check on actual amounts of precipitation). As noted in the conversation here, this seems like just an ECMWF thing vs. something all the models have, so we’ll have to see if anything comes of it. From the bulk of the guidance I’m seeing, the back side of the next system sort of looks like classic westerly flow with moisture from the lakes helping out the northern 1/2 to 1/3 of VT and NH with some snow. It doesn’t look like a robust signal, so maybe just a few inches in the mountains. The BTV NWS mentions it in their AFD: Area Forecast Discussion...DELAYED National Weather Service Burlington VT 717 PM EST Fri Dec 11 2020 .LONG TERM /MONDAY THROUGH FRIDAY/... As of 347 PM EST Friday...Fairly quiet weather will prevail through the first part of next week. A upper shortwave will rotate by just to our north Monday, pushing a front through with a second shot of colder air. This front combined with a bit of lake enhanced moisture will allow rain/snow showers to develop Monday afternoon into the evening, mainly across the northern mountains.

I didn’t get a chance to put them together until today, but I’ve got a few images from yesterday’s tour up at Bolton:

I went for a tour at Bolton today, so I can pass along the elevation profile for snow depths I saw, and some observations. Here are the snow depths I observed: 340’: 2” 1,000’: 3-4” 1,500’: 4-5” 2,000’: 7” 2,500’: 8-9” 2,700’: 9-10” 2,700’ was as high as my travels took me today, so I can’t provide observations above that level, but snow depths probably would have increased a bit more with elevation. The resort is reporting 4-8” of new snow in the past 24 hours, and 10” in the last 48 hours, and that recent snow is probably making up a lot of what I saw. There’s decent substance to the snow (i.e. it’s not just fluff), but really not too much base below that snow from what I saw. I just don’t think there was any dense snow, or rain-affected snow that had a chance to consolidate below these most recent accumulations. The snow quality is good though; the snowpack I encountered was right-side up with some medium weight density snow below fluffier powder on top. I’m surprised to see a depth of only 8” at the Mt. Mansfield Stake at 3,700’, but I’m not sure when that depth was last updated. Based on the amount of liquid equivalent that seemed to be in the snow, and the sub-freezing temperatures up there, this would likely be the start of the winter snowpack unless we get a really warm/wet, long-duration event. Consolidating the snow that’s there right now and/or adding some water to it would certainly help form a base. I’m not sure if the snow we have in the valleys around here is quite enough to mark the start the season’s snowpack, but it’s possible.

Event totals: 3.3” Snow/0.24” L.E. Details from the 12:00 P.M. Waterbury observations: New Snow: 0.2 inches New Liquid: 0.03 inches Snow/Water Ratio: 6.7 Snow Density: 15.0% H2O Temperature: 36.0 F Sky: Cloudy Snow at the stake: 3.0 inches

Event totals: 3.1” Snow/0.21” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 1.0 inches New Liquid: 0.10 inches Snow/Water Ratio: 10.0 Snow Density: 10.0% H2O Temperature: 33.3 F Sky: Flurries Snow at the stake: 3.5 inches

We’ve been in a bit of a lull for the past few hours with just light snow/flurries, but it looks like there’s another pulse of moisture moving in from the northwest that could reinvigorate the snowfall: