J.Spin

December Totals Accumulating Storms: 11 Snowfall: 30.0” Liquid Equivalent: 3.02” 2019 Precipitation: 61.49” December snowfall came in right at 30.0 inches, which is definitely lean with average being closer to 40 inches. Thanks to these last couple of storms at the end of the month though, snowfall did end up better than the 25.1 inches from last season. December can be a very impressive snow month here with moisture of the lakes still in play, and that potential January arctic cold and storm suppression not typically in the picture yet. But with this December in the books now, it’s been a surprisingly long time since we’ve had a strong one with respect to snowfall – looking at my data it’s been since the 2012-2013 season, which had 49.5 inches of snow. The 11 accumulation storms this month was right about average, but total liquid equivalent was a couple inches on the lean side, and snowpack was well below average, so it’s really going to go down as a pretty lackluster month. I haven’t summed SDD for the snowpack, but I’m sure it’s quite low. Although we’ve maintained snow since the pack began back on November 8th, it’s limped along at just an inch or two during the middle of the month. Mean snowpack right now is close to a foot, so we’re still several inches below that, and it’s only been the past week that’s it’s really started to increase again. November was a bit above average on snowfall, but with December being slow, it’s not surprising that we’re a little behind average pace on the season. Mean snowfall to this point is ~55” and we’re at ~50”, so it’s lagging a little, but it’s not really a huge deficit at this point.

Nobody loves hard data more than me, so I think it’s awesome when people post these to speak to the “model X is better than model Y” weenie-ness. However, there are at least a couple of points that people never really seem to drive home sufficiently for me: 1) How does model performance with respect to 500 hPa correlation (which I’m assuming is analyzed globally for the 20° – 80° N region in these data sets?) actually relate to the model’s effectiveness as a guidance tool for sensible weather at the surface? Beyond that of course, how much utility is there in that analysis for the model’s region-specific performance for a certain part of the globe? 2) So you’ve already got the above factors in play, and then, how are you going to convince me that a couple of hundredths of a difference in correlation coefficient is even relevant? The trend in model difference (and actually a bit of correlation improvement) is clear over the course of those years, and with so much data, the stats may be there to support a statistical difference between the anomaly correlation of the two models. Regardless of that outcome though, it still doesn’t speak to the relevance of a 0.03 difference in correlation coefficient to the actual utility of the models. Again, I love when people post these types of data, but I’d like to hear more about whether or not they actually speak to a realistic difference in model performance that matters to forecasting.

I’ve seen various people on the boards get confused on this, and it’s because there’s not necessarily any correlation between a system’s resolution (what’s the smallest level of detail that can be discerned), accuracy (how close are you to reality/expected value) and precision/variability (reproducibility). I don’t follow the specifics of weather modeling, but from what I’ve seen (and this can be the case in other systems as well) there’s typically an inverse correlation between resolution and variability. Some types of output from the ensembles are sort of an example of this with smoothing/low resolution. Low resolution output will likely be less susceptible to variability in some cases because you’re not even going to see changes below a certain threshold.

Event totals: 3.1” Snow/0.21” L.E. Details from the 9:00 P.M. Waterbury observations: New Snow: 0.8 inches New Liquid: 0.05 inches Snow/Water Ratio: 16.0 Snow Density: 6.3% H2O Temperature: 31.8 F Sky: Flurries Snow at the stake: 6.0 inches

I’m surprised nobody brought up borderwx in terms of northerly location; his latitude has got to be close to 45° North. There’s also someone in the Plattsburg area now who indicated he was pretty far north, and don’t we have someone in St. Albans as well? We’re at 44.36° North here in Waterbury.

Event totals: 2.3” Snow/0.16” L.E. Details from the 3:00 P.M. Waterbury observations: New Snow: 0.9 inches New Liquid: 0.07 inches Snow/Water Ratio: 12.9 Snow Density: 7.8% H2O Temperature: 32.5 F Sky: Light Snow (2 to 4 mm flakes) Snow at the stake: 5.5 inches

Event totals: 1.4” Snow/0.09” 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: 30.0 F Sky: Cloudy Snow at the stake: 5.0 inches

Event totals: 1.1” Snow/0.08” L.E. Details from the 12:00 A.M. Waterbury observations: New Snow: 1.1 inches New Liquid: 0.08 inches Snow/Water Ratio: 13.8 Snow Density: 7.3% H2O Temperature: 31.5 F Sky: Light Snow (1 to 7 mm flakes) Snow at the stake: 5.0 inches

Event totals: 5.2” Snow/0.85” L.E. We had light snow/flurries much of the day today, but temperatures also crept above freezing here in the valley, so accumulation was slow. The above totals should be the final numbers for Winter Storm Gage, and anything we get tonight I’ll roll into the next system that is currently moving in from the west. 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: 31.6 F Sky: Cloudy Snow at the stake: 4.0 inches

Event totals: 5.1” Snow/0.84” L.E. Details from the 12:00 P.M. Waterbury observations: New Snow: 0.5 inches New Liquid: 0.02 inches Snow/Water Ratio: 25.0 Snow Density: 4.0% H2O Temperature: 35.2 F Sky: Light Snow (2 to 10 mm flakes) Snow at the stake: 4.0 inches

Event totals: 4.6” Snow/0.82” 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: 30.2 F Sky: Light Snow (2 to 8 mm flakes) Snow at the stake: 3.5 inches

Event totals: 4.3” Snow/0.81” L.E. Details from the 12:00 A.M. Waterbury observations: New Snow: 0.7 inches New Liquid: 0.06 inches Snow/Water Ratio: 11.7 Snow Density: 8.6% H2O Temperature: 30.2 F Sky: Flurries Snow at the stake: 3.5 inches

Indeed, we’ve had ¾” of liquid put down into the snowpack so far here in the valley, so that’s a solid resurfacing above the old base. Apropos on that note, right in line with the forecast it’s just switched back over to snow down here at 500’ in the valley, with huge flakes pouring down. Hopefully the mountains can catch a solid topping over all the dense stuff we’ve been getting.

Event totals: 3.6” Snow/0.75” L.E. There was another period of light freezing rain around here in the midafternoon period, and then the precipitation changed back to sleet. More recently we’re starting to get some snow in the mix as well, and the forecast indicates that precipitation is supposed to change fully back over to snow this evening. Details from the 6:00 P.M. Waterbury observations: New Snow: 0.4 inches New Liquid: 0.10 inches Snow/Water Ratio: 4.0 Snow Density: 25.0% H2O Temperature: 28.9 F Sky: Light Snow/Sleet Snow at the stake: 3.0 inches

As long as it’s been treated I don’t think it should be too bad in this area – precipitation isn’t all that heavy right now (some sleet with occasional flakes) and temperatures aren’t overly cold.

Event totals: 3.2” Snow/0.65” L.E. The precipitation has been mostly sleet this morning, although there was some glaze in there as well that indicates we had some freezing rain overnight. More recently, snow has been mixing back into the precipitation as well. Details from the 12:00 P.M. Waterbury observations: New Snow: 0.7 inches New Liquid: 0.26 inches Snow/Water Ratio: 2.7 Snow Density: 37.1% H2O Temperature: 30.4 F Sky: Sleet/Snow (5 to 15 mm flakes) Snow at the stake: 3.5 inches

Event totals: 2.5” Snow/0.30” L.E. Details from the 6:00 A.M. Waterbury observations: New Snow: 1.3 inches New Liquid: 0.16 inches Snow/Water Ratio: 8.1 Snow Density: 12.3% H2O Temperature: 31.5 F Sky: Light snow grains/sleet Snow at the stake: 3.5 inches

Event totals: 1.2” Snow/0.14” L.E. The precipitation here has generally been snow, but I did see some more granular flakes/sleet out there at one point that probably bumped up the density of the accumulation a bit. Details from the 12:00 A.M. Waterbury observations: New Snow: 1.2 inches New Liquid: 0.14 inches Snow/Water Ratio: 8.6 Snow Density: 11.7% H2O Temperature: 30.0 F Sky: Snow (2 to 15 mm flakes) Snow at the stake: 2.0 inches

It looks like snow started up here in Waterbury around 8:45 P.M.

I’ve got the updated advisory and projected accumulation maps from the BTV NWS below – they indicated that the latest guidance has been a bit warmer, with more mixed precipitation and slightly less snow, so it looks like they adjusted the maps accordingly.

Below are the latest maps for upcoming Winter Storm Gage from the BTV NWS. For projected accumulations through midday Tuesday, shading is generally in the 6-8” range for snow in valleys in this area, with some 8-12” shading for the parts of the spine of the Greens. The point forecast here suggests something in the 5-11” range through Tuesday, although the models also suggest another couple of days of snow with upslope on the back side of the storm cycle continuing into Thursday: .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 452 AM EST Sunday...We remain on the backside of an upper low slowly progressing eastwards on Wednesday. There are still a few vort maxes within that will advect across the North Country during the day. Coupled with a cooler air mass and southwest flow, we should see favorable conditions for snow showers during the day. This will be most true along the Greens and Adirondacks, where orographic enhancement will aid development. The slopes will benefit for the New Year.

Here’s this afternoon’s projected accumulations map from the BTV NWS through 7:00 P.M. Tuesday:

I just got a text alert that we’re under a Winter Storm Watch in association with this next system, which has been named Winter Storm Gage.

I saw that in the discussion and was going to post about it as well. The models have been showing some potentially decent backside snows for quite a while, even back when the storm looked like it was going to be substantially warmer. Ideally it would be nice to get some dense snow topped off by higher ratio powder to cover the old base and set up the powder skiing, but we’ll have to see how it plays out. The BTV NWS mentioning it is a good sign though.

Event totals: 0.2” Snow/0.04” L.E. We picked up a couple tenths of snow on the front end of this system, but since then the precipitation has generally been liquid and very light. We’re still under a Winter Weather Advisory in the area until 11:00 A.M. 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: 34.7 F Sky: Cloudy/Mist/Sprinkles Snow at the stake: 2.5 inches