J.Spin

We’re definitely watching Ginx – after this current event, that’s the next one in the bread and butter lineup. The BTV NWS isn’t concerned about it too much around here at this point, but we’ll see what happens as it gets closer: Area Forecast Discussion National Weather Service Burlington VT 922 AM EST Sun Dec 27 2020 NEAR TERM /THROUGH MONDAY/... As of 922 AM EST Sunday...Southerly flow will increase overnight tonight into Monday ahead our next approaching system. Gusty southerly flow is expected especially in the Champlain Valley with sustained winds 15 to 20 mph with gusts upwards of 30 mph likely, locally higher over the broad lake. Main surface low pressure will pass west of the area and pull off northward into southern Quebec. Temperatures warm tonight into Monday therefore thermal profiles will be supportive mainly of mountain snow and valley rain. Most favored area for steady precipitation will be across western New York with scattered precipitation across Vermont. QPF amounts will generally be a few hundreths to around 0.10" across NY and between a trace and a few hundreths for VT. Snow amounts will generally be confined to a dusting to up to 1" for the Adirondacks.

Exactly; the fact that we’ve already surpassed those snowfall numbers just two days into the forecast period really makes it “iron clad” (as they say), and very hard to argue against exceeding the projection. Sure, snowpack can decrease, but it’s rare to see snowfall numbers decrease once they’re recorded. Yeah, it’s sticking one’s neck out to guarantee that we’re going to exceed those projections with two weeks to go, but sometimes you have to take big risks and ride out your calls.

I know we’re still a full two weeks out from when legitimate verification can be assessed on those projected snowfall numbers, but I honestly expect sites like Mansfield, and even your house, to surpass what the map shows for them.

That is really interesting PF. That observer has got to be measuring/clearing just once a day of course, but even that can’t explain that much compaction. It’s almost as if they’re measuring/clearing even less than once a day and getting more settling than they should. But that can’t explain it for this event – we know when this event started, and we can see everyone’s current depth in the CoCoRaHS data. And, even if you only clear once in a 24-hour period, you can still measure when the snow is at its maximum depth (but I’m guessing this observer doesn’t practice that option). I’ve been doing 6-hour clears and liquid analyses on this event, and you can see the difference is only 0.7” (5.2” collected vs. 4.5” current depth). That should really be about the maximum settling anyone should be seeing at this point. So how does that site settle so much? They’re still getting the liquid, so you’re right, it’s as if collection is done on a surface that is melting from below. Another possibility I guess is that the observer collects in a spot with a bit of wind that is destroying the loft of the dendrites. This morning’s accumulation was definitely fragile at almost 40:1, so with snow like that, wind compaction could be a contributor. What type of results does that site report for dense snow events?

Event totals: 5.2” Snow/0.18” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 1.5 inches New Liquid: 0.04 inches Snow/Water Ratio: 37.5 Snow Density: 2.7% H2O Temperature: 23.5 F Sky: Light Snow (2 - 5 mm flakes) Snow at the stake: 4.5 inches

I don’t think we saw any 3”/hr snowfall this evening, but it was pretty close over a shorter period, probably in the 2.5”/hr range. Accumulation on the boards at 10:00 P.M. was 0.8”, and then it was 2.0” at 10:30 P.M., so that would suggest close to 2.5”/hr during that block. You can see on the radar when those 30 db returns coalesced here in the Winooski Valley, that’s the period when the snowfall was most intense:

Event totals: 3.7” Snow/0.14” L.E. Details from the 12:00 A.M. Waterbury observations: New Snow: 2.8 inches New Liquid: 0.11 inches Snow/Water Ratio: 25.5 Snow Density: 3.9% H2O Temperature: 24.1 F Sky: Snow (2 - 15 mm flakes) Snow at the stake: 4.0 inches

Yeah, it’s definitely picked up over the past 20 minutes or so. I was guessing a 0.5”/hr rate around 9:00 P.M., but it’s been ramping up a bit – it looks like 0.4” in the past 30 min, so getting closer to a 1”/hr rate now. You can see a bit of fire hose spray movement on the radar:

I just checked out the radar and I see that pulse pushing in. We’ve had generally just flurries since my 6 PM observations, but we’ll see if this next round kicks the snowfall rate up a bit more. You can often tell if the moisture pulse is getting a bit more serious when the radar switches sensitivity modes.

Event totals: 0.9” Snow/0.03” L.E. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.7 inches New Liquid: 0.03 inches Snow/Water Ratio: 23.3 Snow Density: 4.3% H2O Temperature: 27.9 F Sky: Flurries Snow at the stake: 1.0 inches

While snowfall up here in NNE hasn’t been atrocious, Dryslot’s point is well taken and speaks to the fact that snow preservation has definitely been below average. It’s going to be quite evident in those places like NW Maine that should really be (on average) developing their substantial winter snowpack at this point. Ginx is definitely on track with the map for the SNE/NYC complaining stuff though. I’m pretty sure I’ve heard people down there mentioning how they’re ahead of average on seasonal snowfall? Haven’t some people down there had not one but two substantial synoptic storms at this point?

Clearly we need to get going on some appropriate images/icons for the current event:

Checking out the Bolton Valley Main Base Webcam, it seems like a similar situation. I see that it’s snowing steadily and they’ve quickly started to cover up those bare areas of natural terrain.

Event totals: 0.2” Snow/Trace L.E. We’ve had light snow of varying intensity this morning since the flakes started up around 10:00 AM. It’s not actually super dry accumulation, since we’re only occasionally seeing slightly larger flakes above the 5 mm range, but average liquid from two stacked cores was 0.0049”, so it rounded down to zero for a trace in this analysis. Details from the 12:00 P.M. Waterbury observations: New Snow: 0.2 inches New Liquid: Trace Temperature: 28.9 F Sky: Light Snow (2 to 5 mm flakes) Snow at the stake: Trace

Wow, I never knew it was the resort running that Co-Op. I just figured it was an independent individual living up there in the condos or something. I always assumed that to be at the level of an official Co-Op, you really had to be thoroughly trained, committed, and very objective. Also, from what I’ve seen, you also have to be specifically selected and vetted by the NWS to cover a location that they deem necessary to provide public information as part of their network.

We had a decent amount of sun earlier this morning, but it clouded up pretty quickly over the last hour or so, and we’ve got some flakes falling now. You can definitely see the quick approach of that moisture from the west on the radar:

There was a trace of snow that whitened the ground a bit here this morning, but as far as I can tell, that, and that touch of front side snow from Wednesday, was all we picked up from Winter Storm Harold at our site. Potential snow from the lakes looks to be the next opportunity as you noted – Lake Effect Snow Warnings and Winter Weather Advisories are visible on the BTV NWS alerts map off to the west. That doesn’t mean the snow will necessarily make it over here, but it’s always a good sign that a decent event is going on for Lake Ontario, so the moisture is around. After that, there’s a potential small system to watch Monday into Tuesday.

That can definitely be done in your location, it will just depend on the makeup of the front. I think snow from fronts such as this are part of the fraud crew in SNE, but it’s definitely different up here That’s what’s so great about winter up here in the mountains though – as I mentioned, while indeed you may not get all snow from every storm (this December is trying to make that blatantly obvious), you will get some snow from just about every storm. At least that’s how it works in this area. We sort of have a bit more of the Great Lakes/LES hookup over here in the Northern Greens to make that happen, and we’re still trying to figure out exactly how things go in your neck of the woods, but you should get in on a lot of it (Alex seems to get in on most of it in his location). Our point forecast here suggests an inch of accumulation through tomorrow night, and the Mansfield point forecast is in the 2-5” range, so anything in that realm is possible. These fronts can be funky because the air is trying to dry out as the colder temperatures arrive, so sometimes they can flop, even here. Typically, there’s some snow to wring out though.

There were model runs showing that sort of result for this current storm as well. It’s not impossible, but in my experience, you really need something more than just the front pushing though (such as touches of redevelopment) to get substantial snows. Obviously in terms of locations, the Northern Greens can wring out moisture with the best of them, but I don’t think I’ve ever seen more than a few inches of snow from a pure frontal passage. It’s possible that the models are picking up on something that’s changing that back side of that modeled storm to something more than just a typical cold frontal passage, and I’m sure the meteorologists can comment on that.

That’s right. Any resort that tried to incorporate manmade snow into their season snow totals would pretty much be laughed at. If they wanted to play that game then each season’s snowfall could essentially be infinite.

The snowmaking is totally unrelated to season snowfall (unless a resort is totally clueless and doing something wrong).

There’s only so much correlation between snowfall and snowpack unless you’re taking about high-elevation spots in the Rockies, Sierra, etc. that don’t see any substantial melting/snowpack loss throughout a typical season. That correlation gets a bit better here as we move farther into the season and you get snowpack down that is just too thick and dense to melt with an occasional warm sector storm, but we’re still too early to be there. Although that 67” snowfall number for the season thus far at Jay Peak is decent, it’s likely a bit behind average pace, and the same would go for that Mansfield/Stowe 55” number. The Northern Greens from Bolton Valley through Jay Peak typically average about 2X the snowfall I record here at our site (e.g. if I record 150” they’ll be in the 300” range, and if I record 200” they’ll be in the 400” range, etc.), so if our average through 12/25 here is 41.0”, average snowfall pace for them at this point should be 80”+. I’m not sure if PF has daily season averages for his Stowe plot, but I know he’s got monthly averages and should be able to say where the mountain’s snowfall should be by the end of this month with respect to average pace.

My data say that we could hardly be more average to this point in the season than what we’ve seen. We’re at 40.1” of snow on the season, and we just fell behind average snowfall yesterday (12/24 mean = 40.4”). Mean snowfall through today is 41.0”, but our point forecast suggests we won’t see any additional snow here until after midnight. Things may feel a bit more off of average pace than they are due to the fact that November was better than average on snowfall, and December thus far has been below average. Also, I suspect snowpack (SDD) is behind average pace as well, which can give the month a less average feel. Mean snow depth for this date at our site is roughly 7 inches, and obviously we’re below that with only a trace out there right now.

Yeah, but you know it’s not going to play out like that around here. Heck, Mansfield will probably get more than that 1” from the snow on the back side of this system and the subsequent LES. It just seems like it would be hard to go 16 days at this time of year without substantially more snow than that due to the immovable lift of the mountains.

Just check on what PF has recorded for the season on Mansfield (55” I assume). You know that’s going to be a rock solid number. Assuming both resorts started counting snowfall at roughly the same time, just add roughly 10 or 20% onto the Stowe number, and if Jay Peak’s number is in that range, it’s probably about on track.