J.Spin

Well, it seems like monster runs appearing closer to the system is a good way to go. We’ll see what the BTV NWS has to say in their next AFD.

The BTV NWS has Winter Storm Watches up now for the system affecting the area over the next couple of days. Both the discussion and the projected snowfall map suggest accumulations topping out in the 12-18” range at elevation in the Northern Greens. Area Forecast Discussion National Weather Service Burlington VT 627 AM EST Thu Nov 25 2021 .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/... QPF forecasts have remained steady with this cycle, and with that, there`s been little change to the forecast liquid and snow amounts over the forecast area. Amounts between 4" and 10" are expected within the winter storm watch area, with northern summits of the Greens seeing locally higher amounts in the range of 12-18". We will also see snow accumulations across the valley floor, especially if the surface low over southern New England develops quickly. For now, have indicated 0.5" to 3" across most of the lower valleys, though there are a few spots with 4" amounts, particularly north.

Event totals: 4.0” Snow/0.10” L.E. These above totals should be it for this event – the streamers seemed to wind down last night around 1:00 A.M. and the sky is just partly cloudy now. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.6 inches New Liquid: 0.01 inches Snow/Water Ratio: 60.0 Snow Density: 1.7% H2O Temperature: 21.7 F Sky: Partly Cloudy Snow at the stake: 2.5 inches

Event totals: 3.4” Snow/0.09” L.E. Details from the 12:00 A.M. Waterbury observations: New Snow: 2.5 inches New Liquid: 0.05 inches Snow/Water Ratio: 50.0 Snow Density: 2.0% H2O Temperature: 23.9 F Sky: Light Snow (2-20 mm flakes) Snow at the stake: 2.5 inches

It’s been pretty steady here, not inch per hour stuff, but probably ½“/hr. stuff. This evening has definitely been the most productive period of the day though, both in terms of snow and L.E. The next analysis for our site would be at midnight, so we’ll see where things stand, but I think we’re at about 3” for the storm thus far. We’re used to mountain magic, but this is a bit more potent than the forecasts would suggest - these bonus snows for the mountains and valleys are great when there’s not actually a “storm” around. The streamers are certainly laying down some accumulations where they’re hitting:

LOL, yea, that’s apparently been the latest weenie attempt at a pejorative for the mountain climates. The whole effort is obvious, but whatever helps entertain them through the drudgery I guess.

It actually was sort of a mystery at first, and it probably wouldn’t have been too big a deal if it hadn’t been quite as widespread and persistent. Once the BTV NWS AFD links started working, they did talk about it in a couple of spots: NEAR TERM /THROUGH WEDNESDAY/... As of 944 AM EST Tuesday...With the cold air mass now in place, flurries are being squeezed out of a shallow cloud layer in portions of the Adirondack region and northern Vermont. SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 322 PM EST Tuesday...heading into Friday evening/night as the upper low shifts east and phases with offshore shortwave energy (which coincidentally is what`s causing snow showers today), it`s blocked by a 1040mb high parked in the northern Atlantic. But watching that stuff just plow into the spine all day, it does leave one scratching the head a bit with the inclination to still just chalk it up to…

We’ll probably have a bit more in the near future – the radar looks like it’s ramping up a bit the way it did earlier this afternoon.

Event totals: 0.9” Snow/0.02” L.E. We had continued snow in the afternoon here at our site to about the same tune as the morning. I headed to Burlington in the afternoon on some errands, and snow accumulations really dropped off pretty quickly west of the pass here – Bolton Flats had just an isolated dusting in areas where the snow had collected. There really wasn’t much accumulation to note in the Champlain Valley, but the views were great. You could see areas off to the south and east with some breaks in the clouds, the greater Burlington area was cloudy with occasional flakes and light snow showers, and then off to the east the mountains were socked in with snow. In town it definitely felt like one of those November holiday types of days with the snow and people ramping up for Thanksgiving. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.4 inches New Liquid: 0.01 inches Snow/Water Ratio: 40.0 Snow Density: 2.5% H2O Temperature: 25.0 F Sky: Light Snow (2-5 mm flakes) Snow at the stake: 0.5 inches

The BTV NWS did make an update to their discussion to better reflect today’s conditions: Area Forecast Discussion National Weather Service Burlington VT 100 PM EST Tue Nov 23 2021 NEAR TERM /THROUGH WEDNESDAY/... As of 100 PM EST Tuesday...Flurries have become more of a snow shower with a powdery dusting seen in parts of northern and central Vermont during the late morning into early afternoon. Have added mention of snow showers into much of this area, but little impact is expected with negligible liquid equivalent and modest wind and visibility restrictions.

Event totals: 0.5” Snow/0.01” L.E. This event wasn’t really in the forecast, but it’s definitely putting down a fresh layer of white and making the most of the available moisture thus far. We had a half inch down at noontime, but there’s been almost another half inch since then. The sub-freezing temperatures even down into the lower valleys at midday is clearly helping with the efficiency of accumulation. Details from the 12:00 P.M. Waterbury observations: New Snow: 0.5 inches New Liquid: 0.01 inches Snow/Water Ratio: 50.0 Snow Density: 2.0% H2O Temperature: 27.9 F Sky: Light Snow (2-15 mm flakes) Snow at the stake: 0.5 inches

I was able to get the latest BTV NWS AFD that discusses all the snow that’s around today. It appears that the snow is associated with an upper-level trough moving slowly across the area with weak forcing and low-level moisture. They could certainly update the discussion though, because the snowfall around here is more robust than that text would suggest. It was on and off snow showers earlier this morning with even some occasional breaks of blue sky, but now it’s wall-to-wall snow, with reduced visibility at times. I was just back in the center of town and it’s the same thing there. The precipitation is still light, fluffy snow, so I don’t expect they’ll have to worry about road conditions, but with the radar showing that there’s more moisture upstream, these conditions will probably continue for a bit. Area Forecast Discussion National Weather Service Burlington VT 945 AM EST Tue Nov 23 2021 NEAR TERM /THROUGH WEDNESDAY/... As of 944 AM EST Tuesday...With the cold air mass now in place, flurries are being squeezed out of a shallow cloud layer in portions of the Adirondack region and northern Vermont. With sub-freezing surface conditions, seeing some very light accumulation of snow, including on high elevation roads in Westfield, Canaan, and Buels Gore this morning. Previous Discussion... Upper level trough will be slow to move across the area today and is not expected to exit the region until tonight. Weak forcing and some low level moisture is helping to enhance some cloud development over the area and there is also quite a bit of cloud cover upstream. As a result have added a bit more cloud cover to the forecast and even threw in a few flurries over the higher terrain in northern Vermont.

There was nothing falling at observations time this morning, but in the past 10 minutes or so, a fresh round of flakes has begun to fall. I hadn’t noticed until this morning that our high temperature isn’t even expected to get out of the 20s F today, so there’s been no issue with accumulation. Unfortunately with the way the forecast discussions are not up to date on the BTV NWS site, I can’t get their thoughts on the origin of this current precipitation, but it’s certainly visible moving in on the radar. There’s a bit more upstream in NNY as well. I’m just going to call it a minor disturbance coming in from the northwest for now until the forecast discussion issue is fixed.

Event totals: 0.2” Snow/0.19” L.E. The weather seemed to clear out by yesterday evening, so the totals above are what I recorded here for this most recent system. It definitely whitened up some of those lower slopes that had lost their cover over the past few days.

Typically, it’s a good sign when the signal is there run after run on multiple models. That’s not uncommon though, because as I mentioned earlier, you can often see a lot more run-to-run consistency in the models for certain setups when it comes to upslope precipitation. Unlike many types of storms, the low pressure doesn’t have to be in an absolutely perfect position to get decent results – there seems to be a lot more leeway in positioning. I think a big component of this flexibility is because, as PF says, “the mountains don’t move.” So if you’ve got the moisture and appropriate winds, the forcing is sort of there for you. I don’t typically use the ensembles to look for upslope potential because I’m not usually looking that far out for specific upslope events anyway, and the ensembles seem somewhat coarse for such a mesoscale phenomenon. I guess they do speak to a general look for upslope in the area. I’d say we’re getting into the window of medium range deterministic model use anyway for that potential event at the end of the week. Hopefully PF can weigh in with some of his thoughts on what he looks for when potential upslope events are on the horizon, but the BTV NWS is generally a good resource. They don’t specifically speak to your area, but I’m not sure how much the GYX NWS focuses on the details of upslope events, so they may be the more informative option when it comes to upslope details. The current BTV NWS discussion indicates that they are aware of the potential at the end of the week and watching the setup. They even mention that low pressure positioning that I talked about: Area Forecast Discussion National Weather Service Burlington VT 936 AM EST Mon Nov 22 2021 LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 428 AM EST Monday... There will be a change Thursday night through Saturday as an approaching upper trough Thursday night will close off over the region by Friday night and only reach the Maine New Brunswick area by Saturday. This scenario will bring rain and snow to the area later Thursday night into Friday with the mountains having the best chance for snow. Have raised precipitation chances into the likely category for most of the area during this time period. The upper low positioned over Maine and New Brunswick by Saturday is important for our weather as this would set up a favorable pattern for upslope precipitation.

We picked up 0.06” from the initial frontal passage, and then another 0.12” from the secondary cold frontal passage. We didn’t get any frozen with that second push, but the precipitation just changed over to snow and we’re getting accumulation, so snow levels have now dropped to the valley floors in this area now.

We’ve had 0.05” of L.E. thus far here at our site in the valley. While a tenth or two of L.E. means essentially nothing in the context of snowmaking terrain, for those of us looking to get out on natural snow, this is much more significant. Putting that L.E. down as a dense accumulation (vs. only liquid) just further enhances the base snow that’s out there right now, bolsters it for more resistance from temperatures above freezing, and preps it to be that much better of a base when the powder comes. So while L.E. values like those don’t matter much for snowmaking trails, or even steep natural terrain, they can be very helpful for the low-angle grassy stuff that supports those early powder turns. We’ll have to see what that potential Friday system does, but the current temperatures in the ~2,000’ elevation range are the warmest they’re forecast to be for the next week, so whatever comes from this system really could hang around to help out the natural base.

I think farther to the east, the temperatures must be going up before they come back down later in the storm cycle. If you look at the point forecasts in your area, it shows temperatures rising tonight through tomorrow morning into the upper 30s F before they start to come back down around noontime tomorrow.

I just checked the Sugarbush snowboard webcams, and it’s snowing at their 3,900’ cam, as well as at their 3,125 cam, so the snow level is somewhere below that as you surmised. I’m surprised that snow levels aren’t expected to rise in the near term with the southerly flow, but apparently not? It looks like temperatures stay steady and then come down as the storm cycle continues. I’m seeing L.E. in the 0.1” to 0.2” range mentioned for this storm, so nothing too prodigious, but a nice little addition for the upper mountain areas if the snow line only falls from here.

Yeah, that system is looking colder than this one, and has more upslope potential as well, at least as it’s currently depicted in the models. I don’t know about a strongly defined low that’s right near us, but it looks like the potential money maker could be low pressure assuming a position somewhere from Northern Maine on up into the Maritimes. Variations of that are shown on multiple models, and that’s what would bring that more potent period of upslope snow. That timeframe is only 4 to 5 days out, so definitely something to watch at this point. And watching at this range is even more appropriate than it is in many other storm setups, because a low doesn’t even need to be placed perfectly up there. Sure, some low positions are going to produce better upslope than others, but you get into that general cyclonic flow with some moisture, and the mountains can do their thing. I’ve found that’s certainly one of the big differences in the snow climate up here vs. places like SNE. Getting defined surface lows placed perfectly/appropriately/nearby is great, but it’s a huge crap shoot, and sometimes it seems like areas to the south can spend half the winter waiting for a pattern to set up that will place lows exactly where they need to be to produce decent snow. That’s unnecessarily burning part of the season that could be producing snow (at least in terms of average temperatures), which is probably one of the factors that produces the lower snowfall averages and higher variance in areas to the south.

I’m thinking the snow line starts out in the 3,500’ – 4,000’ range? PF may have looked at the details and have more accurate thoughts. The BTV NWS doesn’t always say too much when the snow levels are high, since travel impacts are low to nonexistent. I’m seeing 3-6” as a point forecast in the Presidentials at ~5,500’, so certainly some help in loading the ravines to bolster the snowpack there. Indeed that snow line is really up there near the resort summits, so not helping out too much there as you said, and I totally agree, let’s hope it gets down into at least the mid elevations of the resorts. As is typically the case, the lower that snow line goes, the better. The BTV NWS has generally light amounts overall, although they do have the snow levels getting down as low as 1,500’ over here, so that’s dropping all the way to the base elevations. Area Forecast Discussion National Weather Service Burlington VT 255 PM EST Sun Nov 21 2021 NEAR TERM /THROUGH MONDAY NIGHT/... As of 139 PM EST Sunday...Total snowfall expected 1-2" across the Green Mtn summits tonight and Monday, and locally 2-3" at summit level in the Adirondacks. At more modest elevations of 1500-2500`, have indicated just a coating to 0.5" snowfall across nrn NY and far nern VT.

Yeah, there’s not really much shown on the back side of that – it may just be one of these that the snow levels drop from the peaks as it progresses, sort of like we’ve seen. It’s not really a rain system though – the 540 line is forecast to be in NNE at the start of the system and it quickly moves southward, and 850 temps are below zero the whole time. Temperatures at elevation in the Presidentials are never even forecast to get out of the 20s F.

It’s not something that really shows up on the global models, but there’s a bit of a potential bonus event that is appearing on some of the mesoscale models for tonight into tomorrow morning. It seems pretty minor, but enough to be mentioned in the BTV NWS AFD below. The first system I mentioned in the quoted text above delivered yesterday’s snows, and the other two seem to still be on track in the modeling. There’s also another event starting to show up at the tail end of the month now, but it’s a bit far out there to say much and might just be leftovers from the preceding system vs. an actual disturbance of its own. You can pretty much see the periods with these systems on the ensembles as well. The pattern does seem to be as advertised, and these aren’t huge events that require special phasing to happen – they’re just moving through in the flow, so there’s a degree of reliability there. These systems certainly aren’t all snow at all elevations, but they do seem like typical November fare. It’s not quite one of the plentiful bread and butter patterns that gives us something almost every other day, but it’s definitely active with systems to monitor that have snow potential. Area Forecast Discussion National Weather Service Burlington VT 1234 AM EST Sat Nov 20 2021 NEAR TERM /THROUGH SUNDAY/... As of 1222 AM EST Saturday... Heading into Saturday night, that upper ridge starts to shift east, and deep southwesterly return flow will develop once again. It seems that there could be some light activity as the ridge moves east during the pre-dawn hours of Sunday with guidance showing a bit more in the way of activity this last cycle. Forcing isn`t substantial, which should prevent much in the way of measurable amounts. Overnight lows in the mid 20s to mid 30s.

Event totals: 0.2” Snow/0.62” L.E. We picked up a bit more accumulation today, but the sky has been clearing and there’s not much on radar, so that may be the last of this system.

At observations time this morning I found some accumulation on the board – it was partially melted and not immediately obvious where it had come from, but the radar did show some bands that had moved through earlier. It was a few degrees above freezing at the point, so it may have been something like graupel or sleet that can survive temperatures above freezing for a while. It started snowing just as I was leaving the house, with much more standard, fluffy flakes – presumably thanks to the lakes and/or northwest flow. We’ve even had flakes falling here in Burlington today, with a couple of stronger squalls, and I see on our webcam that we’ve had some accumulation at the house as well.