J.Spin

Below I’ve got the latest maps from the BTV NWS for the next storm. They’ve got some substantial accumulations expected along the spine of the Northern Greens at this point, and we’ll see how things change with the next update.

Event totals: 0.2” Snow/0.02” L.E. Details from the 10:00 P.M. Waterbury observations: New Snow: 0.2 inches New Liquid: 0.02 inches Snow/Water Ratio: 10.0 Snow Density: 10.0% H2O Temperature: 32.9 F Sky: Flurries Snow at the stake: 2.0 inches There were a few flakes in the air when I was leaving Burlington earlier this evening, but that was all I saw until I started to head into the mountains. Light flakes were more prevalent as I got to Bolton Flats, and then increased in intensity as I headed up the pass toward our house. We had a couple tenths of an inch of accumulation at that point, and since then we’ve had some wet flakes of fairly light intensity.

I’ve been noticing that for the potential Thursday and weekend systems. The Thursday one seems to cruise right on by without much of a change in latitude, so it doesn’t seem like the backside flow would be that pronounced. The potential weekend one does appear to curve up toward the Gaspé, which seems to support some upslope flow a bit more. I’m just looking at the surface maps though, I guess there could be some trailer energy in the mid or upper levels that would support what’s being shown.

I actually base most of my driveway snow management on liquid equivalent now, and that works really well for our climate (so it’s another great reason to measure liquid for storms). Unless the storm is over about a half inch of liquid, we typically just pack it down by driving over it with the cars to turn it into that base layer. Even with those smaller events that we pack down, I still typically pull out the shovel to take care of the plow berm at the end of the driveway, since that tends to form a lump if you don’t do something about it. Once we get over that half inch of liquid mark is when I have to start thinking about the snow thrower. There’s sort of a gray area in there in the 0.5”-1.0” of liquid range where it will depend on how the layer is behaving, is there a thaw coming, etc. The 1.0” of liquid point is where we pretty much have to clear it. I will say that after a couple of rather icy stretches last season, I finally got around to getting some chains for my snow thrower. I’d been wanting to get them for a number of years, and it’s definitely got a lot more pulling power now. We’ve got a decent pitch on our driveway, and now I find that I don’t have to be adding the assist in uphill pushing that I’d have to do in slippery conditions (which can be often since we keep a base of snow). It’s a bit tougher moving the snow thrower around the garage with the chains on, but that seems to be about the only downside. I finally had to pull the snow thrower out for the first time this season after that bigger event earlier this month, so I got to try it out. It’s been such a tremendous addition in performance that I wouldn’t go back.

These past couple of days in Burlington have really felt like those inversion episodes we’d get in the Bitterroot when we lived out there, and it’s been a really raw, bone-chilling cold, even though the temperatures are actually pretty modest around the freezing mark. Those mountain valleys in Montana would be under inversion and we’d often sit there for many days while the trees built up beautiful hoarfrost formations. It’s all that moisture in the air that really seems to make it feel so raw, and the lack of sun (unless you go to elevation) means you don’t get any warmth from above either. Thankfully the weather is much more active around here so the episodes don’t last too long before the next system comes around to sweep things out.

Event totals: 0.1” Snow/0.01” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.1 inches New Liquid: 0.01 inches Snow/Water Ratio: 10.0 Snow Density: 10.0% H2O Temperature: 28.6 F Sky: Cloudy Snow at the stake: 2.0 inches We had very light snow falling last night at the house, with generally small flakes of 3 mm or less, and the BTV NWS indicates that the snow was from low and mid-level moisture south of a deepening H5 shortwave trough. We’ve had some flakes in the air even into this morning, but it didn’t seem like anything that would result in accumulation, so I’d say we’re probably done with that system at our site. That was the first of the four systems that the models have been showing this week, and likely the weakest for our area unless the forecast change dramatically. The next system is expected to affect the area later today into tonight: Area Forecast Discussion National Weather Service Burlington VT 1026 AM EST Tue Jan 14 2020 .NEAR TERM /THROUGH WEDNESDAY/... As of 1026 AM EST Tuesday...Another shortwave trough passes just to our northwest tonight...similar to the shortwave on Monday. Increasing dynamic support and sufficient moisture in the lower levels supports the idea of light snow becoming fairly widespread across the area tonight with most locations seeing an inch of less...but a couple of inches in the mountains should fall. And much like the Monday system forecast soundings once again show no ice in the dendritic growth zone and during the overnight hours tonight through about mid- morning on Wednesday the potential for light freezing drizzle will exist.

I was just outside and noticed that we’ve got a bit of light snow falling here in Burlington.

I hadn’t remembered that, but recalled last season’s lackluster December, so when I went and checked my records to see how last January was around here. We had 66.5” of snow at the house, which is certainly a solid January for the valley. With the typical doubling of snowfall I see for Mansfield with respect to our site, that would likely have been over 100” of accumulation for the month at your upper plot.

It doesn’t look like we picked up an accumulating frozen precipitation here at the house this afternoon, so the final totals at our site for Winter Storm Isaiah were 0.2” snow/1.06” L.E. When we were at Stowe this afternoon, they did pick up some frozen on the back side of the system – it wasn’t a ton of depth, but it became quite solid as the temperatures dropped and it took a while to warm up the car and melt it off when we were heading home.

With that solid foundation, I think the local slopes have a shot of being in great shape for the upcoming holiday weekend because we’re getting back into our more typical bread and butter pattern. We’ve actually got four potential systems coming through the Northern Greens in the next six days: there’s one tomorrow into Tuesday, another on Wednesday, one on Thursday, and finally a potentially larger one coming into the area on Saturday. Any one of those alone wouldn’t necessarily get things up to snuff, but collectively they could be quite good. We’ll just have to see, but we were at Stowe this afternoon and there’s a lot of great base out there that just needs some quality snow on top of it.

Precipitation associated with Winter Storm Isaiah seems to have ended, and temperatures are back below freezing, so I cored the pack to see where it’s at on the back side of this storm. The core revealed 0.51” of water, so the liquid in the pack dropped by roughly 1.2” with this system. This system wasn’t a net gain to the snowpack water equivalent down at this elevation, but there is definitely a more substantial base in place relative to what was left after the previous thaw back in mid-December.

Event totals: 0.2” Snow/0.02” L.E. Details from the 2:00 P.M. Waterbury observations: New Snow: 0.2 inches New Liquid: 0.02 inches Snow/Water Ratio: 10.0 Snow Density: 10.0% H2O Temperature: 32.7 F Sky: Cloudy Snow at the stake: 8.0 inches As of 2:00 P.M. we’d picked up 0.2” of frozen precipitation on the front end of Winter Storm Isaiah as it moves into the area. The accumulation on the snowboards seemed like a mixture of sleet, graupel, and a touch of freezing rain.

I cored the snowpack for our site as part of this morning’s CoCoRaHS analysis – snowpack water content here is 1.73” ahead of this next system.

Event totals: 5.7” Snow/0.34” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.4 inches New Liquid: 0.02 inches Snow/Water Ratio: 20.0 Snow Density: 5.0% H2O Temperature: 6.3 F Sky: Mostly Cloudy Snow at the stake: 10.0 inches This event finished off with a final 0.4” of snow last night. To this point at our site it's been the largest storm of the month and the third largest storm of the season.

There wasn’t much on the radar aside from that streamer up near St. Albans, so I didn’t think we’d be seeing anything notable in the near future with respect to snowfall. Sort of suddenly though, that area of snowfall just decided to form up against the spine, so we’ve got some decent light snow coming down again. Like PF said in the other thread, this mesoscale snow that sort of comes out of nowhere like that and isn’t modeled exactly is a nice component to have as part of the winter snowfall.

Yeah, we certainly hit the 3 to 5” that was in the forecast. It was a good shot of liquid as well at roughly a third of an inch – that will certainly help to bolster the snowpack.

Event totals: 5.3” Snow/0.32” L.E. Details from the 4:00 P.M. Waterbury observations: New Snow: 3.7 inches New Liquid: 0.23 inches Snow/Water Ratio: 16.1 Snow Density: 6.2% H2O Temperature: 26.8 F Sky: Cloudy Snow at the stake: 11.0 inches

Ahh, that’s interesting – I thought I heard a roll of thunder that lasted a few seconds, but figured it was one of the trucks down by the loading dock. On hearing this though, I suspect it was indeed thunder from thundersnow.

Some of these pulse have been pretty potent – visibility is actually quite low here in BTV right now with the snowfall. I can see on our webcam that when those stronger echoes passed through our place we picked up more than an inch in short order.

Yeah, I can imagine it would be tough to have warm systems come through and melt out the snow, and not really have any idea when it’s going to come back for places that are heavily dependent on mostly synoptic systems. You’re essentially gambling with the pattern all season. It’s not that bad patterns don’t affect us up in the mountains of NNE, but in an overall sense one just had to look at the snowfall and snowpack averages and that gives you an idea of how often the dice are going to give you something decent. Indeed, the off piste often closes with these systems, and sometimes its due to coverage, but a lot of times it’s simply due to the surface conditions being hard/dangerous. Sometimes you get backside snows and you can almost skip that altogether, and sometimes you just have to wait for the next couple of systems to put down a bit more to soften things up and make them safe. Not every warm/mixed system results in a net gain for the snowpack of course, it depends on the system and the state of the density/moisture of the snowpack going into it, but plenty of messy storms actually do result in bolstering the snowpack. Of course we’d prefer the systems to be all snow because that essentially guarantees a net gain, but in whatever form, we do need some of this synoptic moisture (especially this far to the northwest) to build the pack. Our everyday modest systems are nice and can help in that regard, and they are certainly part of what makes our surface conditions so good, but without the bigger events at times, the pack would be rather meager. When time permits, I like to monitor the SWE in the snowpack for these more notable warm/mixed events because you can get a sense of whether the event was a net negative, neutral, positive, etc. I don’t know how this next one is going to go around here, but the analysis is informative, and typically I know the mountains will do substantially better than we do in the valley.

Yeah, we had a nice round with some big flakes here in BTV – looks like it’s pushing right into the mountains now.

LOL, good attitude! And if you have to focus on a warm system, you can always think about the positive contribution of all that liquid and liquid equivalent going in to enhance the snowpack. You’re in snow country now, so you’ve got to get into that NNE state of mind.

Snowfall has started up again here in BTV, and the radar indicates some additional pulses of moisture are moving into the area:

Nice! We got 0.3” at our site with that pulse – as you can see from the radar, the Winooski Valley was right on the southern edge of that batch. There’s nothing immediately upstream on the radar, but the BTV NWS forecast discussion does indicate additional chances today as features move through: Area Forecast Discussion National Weather Service Burlington VT 936 AM EST Wed Jan 8 2020 .NEAR TERM /THROUGH THURSDAY/... Surface low passing well north of our area will continue to track eastward today. As it moves East, an upper level trough will move in behind it, along with potent shortwave energy diving into the base of upper level trough this afternoon. Will mainly see some scattered snow showers associated with these features today, and looks like it will come through in several rounds. Could see some briefly moderate snow, but mainly light snow showers are anticipated. High resolution guidance indicates a few separate rounds of snow showers. Radar currently shows an area of snow showers pushing across Northern Vermont, and another area moving eastward from Lake Ontario, along with a bit of lake enhancement there. Surface cold front crosses the area this morning, then upper level trough and vorticity advection moves in.

It’s funny you mention the snowfall totals over the past few days because I just noticed it this morning as well. When you send in your CoCoRaHS data each day, your data table comes up to show you the past several days (sort of a nice way to make sure you didn’t miss anything in the past few entries). I looked and noticed just what you mentioned. I checked back a bit, and it’s actually been going on for a decent stretch. There was a short break there for a couple of days, but it’s been an inch or two each day, and when you look at the totals for the past 10 days you can really see how much liquid has been going into the snowpack: That’s why I made that post the other day about how it’s been pretty nice; we’re getting our bread and butter events, the pack has been slowly building, and temperatures have generally been comfortable. Heading out to the bus this morning with the boys we had a couple of inches of new snow, no wind, the trees were all freshly coated, temps were in the upper 20s F, etc. It was just really pleasant. I’m not sure if temperatures have actually been running above average, but if this is what you get then sign me up. It’s nice to punctuate the daily stuff with some larger QPF events for really putting serious liquid equivalent into the pack, but it looks like we’ve got one of those in the queue as well. Obviously they’re best when they’re 100% snow, but other liquid/frozen stuff will still typically build the pack.