eduggs

Yeah Sapporo snow is crazy. If you look at the same number of days it took Boston to get 110", Sapporo probably has 15-20 or so such periods since record keeping began in 1953. And the really crazy thing is there are places very close to Sapporo that get 2 or 3 times as much snow. Sapporo City is not in a heavy snow zone.

Boston does not feel like a big city. But yes, EMA has a large and dense population. Sapporo City on the other hand feels bigger - with a city center that feels more like Manhattan than Los Angeles.

Sapporo City gets very cold and frequently frigid. But the city itself is warmed by the Sea of Japan on NW winds, so it's a bit warmer than inland/mountainous areas. Overall, Hokkaido is colder than SNE.

FWIW, Sapporo is a bigger city than Boston. Obviously metro sizes depend on where you draw the borders, but Sapporo also feels significantly bigger than Boston. And although it isn't particularly snowy compared to the immediate surrounding area, it has received significantly more snow during many months than BOS did that winter. But Japan is kind of in a category of its own.

Yeah it really does hurt. The storm looks like a sure bet down in the Gulf. That's why I mostly look at 500mb and sometimes 250/300mb. The surface is just a response to the upper levels. It's easier to anticipate things falling apart when you look at the upper level charts.

Yup. And it's usually a bad forecast. I'm okay with forecasts of 1-2" or 2-3". Winter QPF is generally forecastable with a higher precision than 0.1 - 0.3". The cases where a 1-3" range occurs locally is usually with high liquid to snow ratios where the fluff factor in isolated bands can significantly increase the local snowfall variability. Regardless, I think it's bad practice to forecast a snowfall range that spans the gap between nuisance and solidly plowable. Sorry for the off-topic...

3" feels like a snowstorm, especially if it's cold and accumulates easily on all surfaces. Most people will be happy with that. 1" usually feels like a nuisance event if hoping for a moderate event and will leave most people disappointed. 1-3 is not a thing. It's an old-fashioned, lazy, range forecast.

Really pretty daytime snow today. But I was surprised it got a little warmer than I expected. A little above 30F now with full clouds. Some melting going on.

Should be a good burst for most of NYC metro over the next 30 minutes or so.

The 1/9 - 1/11 event seems to still be in play despite being a bit of a long shot. I like the shortwave diving south through the upper mid-west midweek. The end of run ICON looked workable but I'd sure like to see some improvement to the GFS & CMC this run. Trof axis is okay but obviously too much confluence as modeled through New England and the Maritimes. We've seen that resolved favorably on occasion through the years.

Every day presents a new configuration of weather features. It's not like we have a perfect standing wave jetstream creating a static "pattern." Snow doesn't come from "patterns." At the local scale, snow is loosely correlated with a set of global ocean-atmosphere-climate indices that are themselves somewhat vaguely defined. It is the nuances of the features, their evolution, and interactions; the details... that determine whether we get snow. It's the "pattern" obsession that leads to so much disappointment. Especially for the people who use long range 500mb height anomalies to try to sniff out favorable periods. Those charts always look better than reality because of the averaging effect that smooths out the critical details. They can sometimes portend temperature trends, but are much less useful for long range snow prediction. Most of us are still in the game for Monday.

Totally agree about single-run caution to avoid possible windshield wiper effect. But this was a really good cycle (plus 18z ECM). All medium range models and ensembles are improved - and it's a meaningful improvement. At this time range I think holding serve two more cycles or so would signal a really good chance of a light to moderate snowfall locally.

I'm mildly intrigued by the 3rd - 4th on the GFS, but minimal ensemble support and lots of disagreement between the other models. No clarity in weenie range when day 7 still isn't close to being resolved.

Brooklyn posts a lot in several subforums and has a red tag. Few people provide a counterpoint to his posts despite their sometimes repetitive and simplistic nature. Non-red-taggers get constant push back so I don't feel it would be constructive to police all their posts.

Really nice plot. The correlation between PNA+ and NYC snowfall jumps out. But one thing that a stickler would say is missing from the analysis to make it statistically robust is an accounting of the relative frequency of time spent in each quadrant. For example, hypothetically if 95% of winter days occurred with an AO- PNA+ combo, observing a majority of significant snow events with these parameters would not be telling. What you're getting at is the relative likelihood of significant snow on any given day with each combination. And for that, some kind of normalization of the data is required.

Gotta marvel at the 12z CMS with 3 rain events and another just past the end of the run as we approach peak winter climo. Fortunately other mid-range guidance starts to differ early in the run.

Yes please occasionally post something other than toggled 500mb anomaly charts that you think show a favorable "pattern" for cold and snow. Better yet, spend some time on analyzing why so many of your highlighted patterns fail to portend cold and snow. Once you have a better handle on that, you will be a much better mid- and long-range forecaster. I'm not sure if this applies to you, but I really think younger forecasters are at a disservice having grown up in the era of tropicaltidbits, pivotweather, and various plotters to view historical data and "patterns." Without a deep understanding of statistics and a more intuitive feel for forecast uncertainty that comes with age and experience, the ease of data access gives youngsters the impression that they understand things that they really don't understand.

Well Brooklyn primarily posts about "favorable" signs - usually mid or long range ensemble mean anomaly charts... over and over again. It's been like that for a few years now if my memory servers me correctly. That seems kind of weenyish to me. Sometimes I appreciate it... but other times a bit more objectivity is warranted. Presumably he will acquire more balance with more experience.

Yeah exactly. In hindsight it's easy to identify what went wrong. But model ensembles 10-15+ days in advance miss key details.

That's slightly more optimistic than I would mentally lock in. But statistically it's not unreasonable.

Nothing on the 12z ECM out past 10 days either. Well other than rain.

Agreed that operational runs are nearly useless past 7 days. Ensembles are decent for airmass forecasting, okay for general storm prediction, and poor for snow forecasting at that time range.

I think you have a short memory. There have been several very favorable looking periods over the past 3 winters that all failed to precede significant snow in our area. I want big snow as much as anyone. But we're ultimately going to need to see it on operation runs inside 7 and particularly 5 days before excitement is warranted.

2 problems with that: 1. The correlation between "favorable periods" and local snowfall is relatively low. 2. Ensemble means out past 10 days have a degree of uncertainty that is large relative to the regional synoptic scale. In other words, model error at that time range significantly exceeds the average synoptic different between rain vs. snow or storm vs no storm. And regional snowfall is driven more by shortwaves in the flow than the longwave "pattern." Since ensembles are heavily diluted by averaging out past 10 days, they cannot "see" the shortwaves that make or break snowstorms for us. That's why modeled favorable patterns fail to portend significant snowfall far more often than they successfully predict it (esp outside mountainous regions). The uncommonness of significant snow as a Bayesian backround state also has to be considered, regardless of what the ensembles look like.

Ensemble charts are averages of dozens of individual runs. That's why a great ensemble "look" often does not lead to a snowy outcome locally. The details are everything with snowstorms and ensembles don't resolve the details.