eduggs

It looks like there's a small chance some NYC urban areas won't hit freezing all January. I think we'll get a seasonably cold day or two at least, but it's not a given.

CMC is northern stream dominant. That feature has to be way out ahead or flat. Only NNE can cash in with a surface low anywhere near the Lakes.

Detroit - Rochester SLP primary track on the 12z GFS is not what most want.

Keep that primary slp south and east of PA and it's game on for all of NNE and possibly further south. As many have noted, the key is to avoid an early phase.

Definitely not at day 4 in the Midwest. But a subsequent phasing of a follow up polar wave when the main low has traversed further east could work out.

I think what happens days 4-5 with the initial wave interaction and slp track through the midwest is actually more important than where the low center is at day 6.

I think that storm broke the algorithm. 8 day storm? Pretty generous 4" coverage on the southern periphery. Getting the NYC to Trenton corridor in that areal coverage also probably helps the score. I guess technically a T is < 4"

Actually I would say there is a potential cold source to our north on Thursday. But the early wave phasing and slp through the midwest pushes it out of the northeast and deep into Canada.

The amplifying and severely negatively tilting trof that's modeled is fun to look at. There's actually a little cold air to our north to work with initially, and this is still 6 days out. So I keep checking too. Problem is all guidance is showing a relatively early phase in the midwest, which quickly scours out the cold throughout the northeast. That means even if a developing coastal slp goes ballistic, there's no available source nearby to tap into. We need to hope for a re-jumbling of the features that shakes out more favorably. 1st goal is to lock in more cold air.

The 0z CMC and even EC are incredible. Days and days of rain beginning next weekend. Presumably coastal flooding too. Most northeast ski areas would probably have to shut down. Peak winter climo season.

I think we need a snowstorm modeled inside 3 days, not a "pattern." To the degree that patterns can even be defined, they are continental to hemispheric in scale. Snowstorms are local to regional.

The Dunning-Kruger effect neatly illustrates so much of what we observe both in life and on this board.

Careful about using those 10+ day ensembles. Any "signal" that you see out in that range should be treated with skepticism. It's fine to interpret what current model guidance is showing. But it should be well understood that those features have a good likelihood of verifying significantly differently than currently modeled.

That said, I could see the early next week wave turning into a minor event. The wave spacing at least on the GFS and NAM has improved. I'm leaning against it because there haven't even been many individual ensemble members that have bitten, much less an OP run. But we do have a snow supporting atmosphere plus an upper level wave.

I'm not sure I've ever seen the 10 day charts look this terrible this time of year on every model. 573dm at 500mb for days and days and days. It looks like June. There's not really even anything to root for except maybe record breaking warmth. We'd need some kind of massive multimodel error just to make it interesting.

The problem is using analogs to predict local weather. Yes the climate is steadily changing, but that's not what happened here.

Seconded. A lot of really smart people have researched extensively and continue to research all the gotcha questions in addition to legitimately interesting climate change issues.

Proximity to the Ocean definitely enhances our snowstorms. The midwest is a little moisture starved, but the ratios will be better than 10-1 in places like Wisconsin. Michigan should do well, especially with some lake enhancement, and even northern IL could do pretty well.

Anybody with access to the GEFS individual members care to share the approximate southeastern extent of the ULL amongst the individuals at 18z and 0z. The past few runs have shifted this feature slightly further SE.

The Canadian has the day 8 threat.

I think we just need a slightly different orientation of the height field. If that ULL is slightly less suppressive or a lobe retrogrades west and dives into the trof, that would work.

GFS still shifting ever so slightly southeastward at h5. We just need 3 or 4 more like that with no steps backward to make things interesting. The ICON shifted a little as well but the RGEM appears not to have.

Great post Don. You bring so much to these discussions. I think we mostly fail to meet you on your level. My only quibble with your excellent analysis is the your handling of sample size and its impact on confidence and uncertainty. But I don't even have a good solution for dealing with small sample sizes in weather-related statistics other than a big shrug. Sometimes there just might be too much uncertainty to draw conclusions.

I'm with you. It's just funny to look at the raw hourly GFS output and see that unusual weather reversal.

It's going to be an interesting and historical moment on Friday when it's 20F and snowing in DCA while it's raining on the summits of Mt. Washington, Mansfield, and Marcy. I think it's happened before, but still rare.