J.Spin

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.

Event totals: 1.6” Snow/0.09” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 1.6 inches New Liquid: 0.09 inches Snow/Water Ratio: 17.8 Snow Density: 5.6% H2O Temperature: 27.0 F Sky: Light Snow (2 to 5 mm flakes) Snow at the stake: 7.0 inches I wasn’t sure how much snow we were going to get overnight with the start of this next system, but the sound of the plow on our road early this morning suggested it was off to a quick start. We actually picked up more snow in just the first round of this storm than the entirety of the previous one.

Event totals: 1.5” Snow/0.05” L.E. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.1 inches New Liquid: Trace Temperature: 29.5 F Sky: Cloudy Snow at the stake: 6.0 inches The tail end of the most recent system brought a final tenth of an inch of snow this morning, and that should do it for that event. The next system in the queue is expected to move into the area tonight, with potentially another 1-3” like this last one, although our point forecast does suggest the potential for accumulations of 3-5”.

Snowpack has indeed been on the low side, but it’s been persistent for the most part since what was really an incredibly early start (even besting last season’s very early start by a couple of days at our site). Overall I’ve really been loving this January weather so far though – if there’s a month to have above normal temperatures, this is definitely it. If I was to write up the winter I’d put those below average temperatures in November, March, and April, and above average temperatures in January. We’re getting snow, and we’re not freezing our butts off in artic cold while the storm track gets pushed far to the south. Sometimes you have to deal with some mixed precipitation when the systems come through, but I’ll take that vs. the cold and dry scenario that sometimes happens this time of year. I know some folks prefer the high and dry scenario more, since it’s great for snow (and ice) preservation, but the snowpack is really too meager to really be going there yet. We definitely need to get more liquid equivalent into it, and if that comes with some mixed precipitation I’d still argue it’s still going to be better than high and dry.

Event totals: 1.4” Snow/0.05” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.3 inches New Liquid: 0.01 inches Snow/Water Ratio: 30.0 Snow Density: 3.3% H2O Temperature: 26.1 F Sky: Cloudy Snow at the stake: 6.0 inches There’s some precipitation pushing into BTV right now on the radar, so we may not be quite done with this event, but we’ll see if anything accumulates in our area: The next system in line appears to be an upper level trough/shortwave with an arctic front that could bring some snow squalls tomorrow.

Event totals: 1.1” Snow/0.04” L.E. Details from the 10:00 P.M. Waterbury observations: New Snow: 0.2 inches New Liquid: Trace Temperature: 20.6 F Sky: Cloudy Snow at the stake: 6.0 inches

Cool stuff PF, and indeed that 24-hour period had a couple of super fluffy measurements that were sub-0.005” of liquid and thus got rounded down to zero. That of course pushed the net ratio for that stretch up to 45 to 1, even though the main measured sample came in at 27.5 to 1. Of the three rounds of measurements I had during that period, the 0.04” reported actually came with the 1.1” of snow at 12:00 P.M. on the 5th. The subsequent two rounds of measurement (0.3” of snow at 6:00 P.M. on the 5th, and then 0.4” of snow at 6:00 A.M. on the 6th) came in with 0.0007” and 0.0035” of liquid, respectively. The second one didn’t miss the 0.005” by much, but ultimately they both got rounded down to 0.00” of liquid. For the most part it should average out over the course of a season, but sometimes you’ll get those days where samples just miss the threshold and get rounded down to zero. The rounding is probably for the better in some respects. For example, the 0.0007” of liquid was probably low anyway – I get to the scale as quickly as I can, but in these small samples, evaporation/sublimation is having an effect. If you leave a core on the scale for a minute or two inside, you can see the mass of the sample decrease as water is lost. It was certainly some of the driest snow I’ve seen this season though – you could simply wave your hand past the snowboard and make it fly away if you wanted to.

Event totals: 0.9” Snow/0.04” L.E. Details from the 4:00 P.M. Waterbury observations: New Snow: 0.9 inches New Liquid: 0.04 inches Snow/Water Ratio: 22.5 Snow Density: 4.4% H2O Temperature: 25.0 F Sky: Mostly Cloudy Snow at the stake: 6.5 inches

It was just cloudy at home in Waterbury, but I’m approaching the Burlington area and they’ve got some light to moderate snowfall occurring.

Event totals: 4.3” Snow/0.31” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 0.4 inches New Liquid: Trace Temperature: 12.6 F Sky: Mostly Cloudy Snow at the stake: 5.5 inches We picked up a final round of super dry snow last night, and that should mark the end of Winter Storm Henry. The next system in line is quickly moving into the area though, with snow expected to start later this morning and roughly 1-3” of accumulation expected down at our elevation and more at elevation: Area Forecast Discussion National Weather Service Burlington VT 639 AM EST Mon Jan 6 2020 .NEAR TERM /THROUGH TUESDAY/... As of 320 AM EST Monday...Cloud cover is overspreading the North Country this morning in advance of an occluded front. This front is expected to bring snowfall to much of the region with northern New York and the spine of the Green Mountains expected to see decent snow accumulations through Tuesday morning. Models continue to remaining good agreement with snow totals generally 2-4 inches across northern New York, 1-3 inches across Vermont and 3-6 inches across the higher summits of the Green Mountains.