J.Spin

Event totals: 1.8” Snow/0.17” L.E. Snow was quite heavy at observations time this morning; certainly in the 1”/hour range or so, but it hasn’t been that way the whole time and there have been periods with less intensity as well. Snow density came in just a bit under the standard 10% mark – 9.4% H2O, or 10.6 to 1 in terms of ratio. Details from the 6:00 A.M. Waterbury observations: New Snow: 1.8 inches New Liquid: 0.17 inches Snow/Water Ratio: 10.6 Snow Density: 9.4% H2O Temperature: 13.6 F Sky: Heavy Snow (3-10 mm flakes) Snow at the stake: 9.5 inches

A quick look at liquid for the latest runs shows most of the models having our area in the 0.50” – 0.75” L.E. bracket, with some of the mesoscale models getting us into the 0.75” – 1.00” bracket, and there are a couple models with the area in the 0.4” – 0.5” L.E. bracket. The CMC was one of those with that lower L.E., but it’s more recently come up to match the other models in that next bracket. We’re a bit south of PF, but our point forecast has ~0.6” of L.E. here at our site, and that seems very consistent with the modeling. That would be 6” at a 1:10 ratio, or 12” at a 1:20 ratio. Our point snowfall forecast sums to 8-12” through Friday night, which may be a bit on the higher side, but they do mention those mid to upper level vortices that I’ve seen PF talking about having the potential to move over the area: Area Forecast Discussion National Weather Service Burlington VT 635 PM EST Thu Feb 24 2022 NEAR TERM /THROUGH FRIDAY NIGHT/…potent embedded 700 to 500mb vort, which wl move directly acrs our cwa btwn 15z-21z Friday, resulting in a period of moderate to heavy snowfall. HREF shows 1 to 2 inch per hour rates with pockets of up to 2.5 inches per hour over the dacks around 18z Friday, which looks reasonable given the idea of strong dynamics and deep moisture within the DGZ. Fluff factor could result in some areas overachieving, but limiting factor wl be extremely quick movement of system, with favorable dynamics/lift and moisture only lasting for 3 to 6 hours from west to east acrs our fa. Our point forecast does have that “heavy snow” listed for the Friday period, so there’s enough confidence to get that put in there. And hey, it’s the Northern Greens, so there’s always the potential for a little extra oomph if things line up to let the orographics help with a touch of extra lift. And as PF said, if dendritic growth isn’t great and it’s tiny flakes, the accumulations will be on the lower side. But who really cares about the exact accumulations numbers aside from the record keeping aspect, it’s the L.E. that matters around here; that’s what’s going to make the difference on the slopes. The current snowpack needs a major resurfacing; that’s all there is to it, so that means getting down as much L.E. as possible. Dense snow might in fact be better than champagne in terms of the resurfacing anyway. Modeling suggests that there are more potential shots of snow over the next week as well, so perhaps we’ll do a little catching up on seasonal snowfall with respect to average.

Seeing the data from regional sites is very interesting, because at our site this has most definitely not been a bottom of the barrel winter up to this point. Even in our small data set of 14 seasons, there are three seasons with less cumulative snowfall up to this point, three seasons with lower snowpack on this date, and both of those parameters for this season are currently within 1 σ of the mean. We’ve had two storms of 16”+, which is already average for an entire season in that regard. The Mansfield snowpack data clearly indicate that the mountains are well off the usual mark in terms of snowpack. I think the same thing happened last year, where the mountains were much farther below average on snowfall/snowpack than the valleys? We actually ended last season with roughly average snowfall at our site, or even slightly above. One would think that the mountains should have lower standard deviation and have higher snowpack/snowfall reliability, but perhaps not? What sort of seasonal weather pattern/trend has to come together to keep the valleys closer to average than the higher elevations?

Event totals: 1.2” Snow/0.44” L.E. We’ve mostly cleared out, so the above totals should be the final numbers for Winter Storm Nancy at our site. As others in the thread noted, the back side snow was surprisingly impactful for travel, and that impact is notable when one realizes that there were just a couple hundredths of an inch of liquid in there. I did see some coatings still on the roads this morning, but much more impactful was the effect those big, fluffy flakes had on visibility. 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: 8.6 F Sky: Mostly Clear Snow at the stake: 8.0 inches

You know I’d be the first to point out if you seemed to be overreacting to apparently unusual winter conditions for your area, but let me split it up between snowpack, and the running total for season snowfall. In terms of season snowfall, we’re certainly behind average pace here at our site (91.6” to date vs. 114.5” for the mean) but it’s still well within 1 σ (31.0”), and I suspect you’re within 1 σ at your site as well. So, sure, we’re behind average pace, but the stats say it’s no big deal. But in terms of your snowpack, I can’t imagine how the current depth is anything but outrageously abnormal. We had 3.5” of liquid equivalent in the snowpack here before that first storm, and you had even more than that. That amount of liquid should typically be enough to survive even two or three of those types of warm sector events, as I mentioned in my post a while back, and this current system wasn’t even that potent. The reason that the disappearance of the snowpack at your site is so weird is that it really should be baked into the climatological record for your area, so if south winds beat up the snowpack like that, then there should be plenty of times during the winter where it disappears. The mean snowpack depth for this date at our site is 16.8”, so it’s probably in the range of 2 feet at your site. Unless your neighbor’s climate is notably different than yours because of protection from winds or whatever (I haven’t checked the data from that site, but we could determine average snowpack for this date), it’s definitely weird that so much liquid equivalent could disappear like that.

Event totals: 0.6” Snow/0.43” L.E. Some models have been showing back side snow in our area from Winter Storm Nancy, but the signal wasn’t all that strong, so I hadn’t given it too much thought. It definitely caught my attention this afternoon though. There were a few flakes falling here and there in Burlington, but as I headed home westward into the mountains, the precipitation ramped up steadily. Accumulations began to appear on the roads around Williston, and by the time I reached the Bolton area I encountered near whiteout conditions with snow-packed roads. Here at the house, the intensity of the snow was enough that I had to put it down as “heavy snow”, since it was in excess of 1-2”/hr. while I was out making the 6:00 P.M. observations. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.6 inches New Liquid: 0.01 inches Snow/Water Ratio: 60.0 Snow Density: 1.7% H2O Temperature: 24.1 F Sky: Heavy Snow (2-15 mm flakes) Snow at the stake: 8.0 inches

I got a phone alert early this morning that Winter Storm Watches are up in the area. The latest BTV NWS maps are below, and the alerts map is an interesting mix of colors that I don’t think we see very often with those Wind Advisories mixed in. The watch text indicates that a general 6-12” of snow accumulation is expected at this stage, and that fits with what’s shown in current Event Total Snowfall map.

Event totals: 2.5” Snow/0.11” L.E. The skies have fully cleared out, so the above totals will be the final numbers for this storm. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.3 inches New Liquid: 0.02 inches Snow/Water Ratio: 15.0 Snow Density: 6.7% H2O Temperature: 13.3 F Sky: Clear Snow at the stake: 11.5 inches

Event totals: 2.2” Snow/0.09” L.E. 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: 22.1 F Sky: Cloudy Snow at the stake: 11.5 inches

Event totals: 1.8” Snow/0.08” L.E. Details from the 12:00 P.M. Waterbury observations: New Snow: 1.8 inches New Liquid: 0.08 inches Snow/Water Ratio: 22.5 Snow Density: 4.4% H2O Temperature: 27.1 F Sky: Flurries Snow at the stake: 12.0 inches

We’ve been running at a bit over an inch per hour here since the flakes first appeared, and that includes the initial ramp up time. You guys up there are surely even above that based on the radar.

I see that snow has started up here at our site in association with this next system moving into the area.

Based on the conversation here, and what I saw on my trip to BTV today, it sounds like the spine westward did better on the back side snow vs. the east side. I guess it wasn’t so much a Froude Number phenomenon, but just where the cold air caught up with the moisture, consistent with the projected snowfall map from the BTV NWS. In line with what Froude reported above, I think modest terrain on the west side should be nice, especially if we get additional snow from this next system. We’ve actually had about 0.20” of L.E. thus far in the back side snows, so I’m looking forward to a bit of low angle touring depending on how this next storm goes.

Event totals: 2.5” Snow/1.21” L.E. The snow tapered off this afternoon, so the above totals should be the final numbers from Winter Storm Miles here at our site. Details from the 6:00 P.M. Waterbury observations: New Snow: 1.6 inches New Liquid: 0.03 inches Snow/Water Ratio: 53.3 Snow Density: 3.3% H2O Temperature: 12.7 F Sky: Partly Cloudy Snow at the stake: 10.5 inches

Between the current storm and that one, you’ll definitely get at least a couple of inches. We’re just about hitting that down here in the valley already, and this is just part of the first storm. I’m sure the mountains are getting hit with lots of wind, but PF will probably do an accumulations check at some point today. Although this doesn’t look like a huge period of upslope on the back side of this current system, there’s still some moisture upstream on the radar, so we can expect at least a little more accumulation.

Event totals: 0.9” Snow/1.18” L.E. At some point the precipitation changed fully over to snow last night because it was snowing this morning at observations time, with 0.9 inches down on the boards. The name given to this system is Winter Storm Miles, and it’s producing at least a bit of backside snow. We’ve had some solid periods of upslope flakes even down here in the valley, and the Bolton Valley Main Base Live Cam at ~2,150’ shows some heavy snowfall. The local radar indicates there’s still a bit of moisture upstream as well. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.9 inches New Liquid: 0.17 inches Snow/Water Ratio: 5.3 Snow Density: 18.9% H2O Temperature: 21.0 F Sky: Light Snow (3-12 mm flakes) Snow at the stake: 10.0 inches

That seems to be the way a lot of people use it, but the term just doesn’t make sense that way – if the storm “cuts” to the east of their area, nobody calls it a “cutter”. If a storm “cuts” through the central Great Lakes, it’s east of some places, like Chicago, but west of a place like Buffalo – so the same storm would be a “cutter” for Buffalo, but not for Chicago. A basis as Coastal indicated, with the term stemming from a fixed geographical area is the most logical, in that it’s based on a storm having a surface low track that “cuts” through the Great Lakes.

Thanks, that’s helpful, and I think I’ve heard the origin in passing before (such as the full expression “Great Lakes Cutter”), but the Great Lakes part is almost always left out, so just seeing “cutter” 99% of the time, the relevance of the term seems to get lost. But why are we so special? A storm that puts Buffalo, or Cleveland, or Chicago right in the meat of the warm sector would typically “cut” through a different part of the lakes, and if a storm passes far enough to the west, it starts to become irrelevant here. And, people have been referring to this current storm as a “cutter” for a week or two, and the surface low isn’t even moving through the Great Lakes – it’s passing east of all the lakes and right through New England. The way people use the term, one gets the feeling that it’s just applied to any storm in which the warm sector hits their area of interest, so maybe there’s some inconsistency in use that adds to the confusion.

As Alex mentioned above, people often make a bigger deal out of these events than is warranted. Because NNE is so wintry, there may be this perception that it’s sub-freezing with snow as the only type of precipitation from November through April, but of course we know that’s not actually the case. I’ll hear people use this term “cutter” seemingly for any system that appears to bring a storm’s warm sector… I guess to a specific location they’re concerned about or something? But it sounds like some sort of nonsensical term a weenie made up for dramatic effect. There are occasional storms that hit just right and have a dramatic effect on the snowpack, but that’s often in situations where the snowpack isn’t all that robust, or it’s some extended warm spell that goes on for days. Even way down here in the valley bottom at our site, the snowpack is quite hefty right now, with multiple inches of liquid equivalent as the NOHRSC plot shows below. And as PF’s recent analyses indicate, there’s three times that amount of liquid in the snowpack at elevation. You can see in the NOHRSC modeling for our site in the plot below that this upcoming system really isn’t expected to have a dramatic effect on the snowpack. The snowpack, especially the mountains, could probably handle more of these if that’s what happened to transpire, but of course it’s far better for the snowpack and snow sports overall if more of the systems come as snow, or at least mostly frozen. The snowpack can only hold so much water and will eventually get “ripe” as PF mentioned.

The BTV NWS has updated their advisories map in association with the upcoming system, so I’ve got that and the Event Total Snowfall map as well. I received a text indicating that we’ve been put under a Winter Weather Advisory, and that’s what covers much of the area aside from the Winter Storm Warning out in the Saint Lawrence Valley. The map has the spine of the Northern Greens in the 2-3” shading.

The latest BTV NWS forecast discussion does continue to mention the possibility with the back side of the this system, starting with a Winter Storm Watch for the Saint Lawrence Valley, but they’re starting to mention areas farther east, so they’ve certainly got their eyes on it. I'd say we’re south and east of the very best snows with this system, but most models show some snow in the area. We’ll see what the models suggest as we get closer. SHORT TERM /THURSDAY THROUGH FRIDAY/... As of 406 AM EST Wednesday...A very complexity and challenging fcst continues to unfold with some sizable changes noted in the 00z guidance. …have issued winter storm watch for 6 or more inches of snow and some ice accumulation for the St Lawrence Valley from 00z Friday thru 15z Friday. Additional headlines are possible for other parts of NY and portions of VT in later fcst packages.

As we get closer to the potential event, nothing is as extreme as those earlier GGEM runs, but the GFS has continued to trend southward and is actually one of the snowier solutions as they all hone in on a blend as was mentioned. The combination of the back side snows from that Thursday/Friday system, plus the snows from the Saturday evening system look pretty nice on some of the models, and could set up some potential fresh snow for the weekend. Right now, the BTV NWS forecast discussion only mentions NNY in terms of the possible back side snow, but I’m sure they’ll bring the Northern Greens into their thoughts if snow possibilities increase there. Area Forecast Discussion National Weather Service Burlington VT 1017 PM EST Tue Feb 15 2022 SHORT TERM /THURSDAY THROUGH FRIDAY/... As of 352 PM EST Tuesday...Before precipitation moves entirely out, some snow will take place across northern New York, yielding about 1-3", give or take an inch or two depending on the low track. LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 1017 PM EST Tuesday...trends in the long range data continue to support the idea of a well defined shortwave will be moving across the region on Saturday. The probabilities of snow showers continue to increase across much of the area and forecast soundings are beginning to show a greater depth of dry adiabatic lapse rates, which suggests enough instability may exist for convective snow showers or squalls. Definitely something to keep an eye on. Otherwise it does look like there may be minor accumulations of snow with this system that could result in some difficult travel conditions.

Event totals: 0.3” Snow/0.02” L.E. I’d say that’s it for this system, as it looks like the snowfall tapered off earlier today. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.1 inches New Liquid: 0.01 inches Snow/Water Ratio: 10.0 Snow Density: 10.0% H2O Temperature: 4.6 F Sky: Partly Cloudy Snow at the stake: 14.0 inches The next potential system in the area is shown on some of the models tomorrow, which the BTV NWS says is due to a weak shortwave in the northwest flow.

The GFS solution does seem pretty extreme to show absolutely no snow from that system around here – it’s presumably possible, but you typically need just the right track to get absolutely zero snow with the Northern Greens orographics. It’s tough because the event is still pretty far out in time though – stepping through the 6Z ECMWF model run on Tropical Tidbits, I couldn’t even get to the point where that low reaches this area because it’s past 90 hours. It would seem prudent to take some sort of blend of the models you showed, and I see that’s what the BTV NWS mentions in their forecast discussion. They didn’t use the GGEM in the package, perhaps because it was the most extreme in terms of colder track, but they talk about their blend below. It’s definitely a possible upcoming system to watch – they finish their discussion segment indicating that the system holds the potential for several inches of snow on the backside on Friday: Thursday night developing sfc low pres wl track from the MS River Valley toward the eastern Great Lakes, while a sharpening cold frnt slowly sags southward toward the SLV. Guidance is still all over the place with regards to position of this very sharp boundary, where progged 925mb temps range from -12C to +6C in a span of <100 miles. The GEM solution is still the coldest and not used for this package, while GFS is the warmest and most delayed in pushing the colder air south and the ECMWF is sort of the middle ground. For example at 06z Friday, GFS shows 925mb temps near 10C at BTV, while GEM has -9C, and the ECMWF is near 0C. For this package have utilized a blend btwn previous fcst and latest NMB guidance, to show rain changing to snow from nw to se acrs our cwa btwn 03z-12z Friday, as temps fall from the mid 40s to mid 50s into the upper teens to mid 20s by 12z Fri. Whenever we have shallow low level cold air, undercutting warm air aloft, the potential for mixed precip, including sleet and freezing rain wl be possible during the transition period on Thurs night. These rapidly falling temperatures with precip occurring wl create a setup favorable for a flash freeze, which could result in a slick Friday morning commute. Several inches of snowfall is possible on the backside of low pres early Friday morning acrs our fa.

Event totals: 0.2” Snow/0.01” L.E. I didn’t know we we’d be getting new snow this morning, but I woke up to find light snow falling and a fresh coating of white over everything. The BTV NWS indicates that it’s from a sharp upper-level trough swinging through the area. 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: 3.9 F Sky: Light Snow (1-2 mm flakes) Snow at the stake: 14.0 inches