brooklynwx99

seethe

cope

that 50/50 and -NAO dipole is already beginning to show up. always very nice to see the deepest negative anomalies in the 50/50 region track that 2 weeks forward - Aleutian LP builds as the Pacific jet extends alongside retrograding Scandinavian ridging and you're looking at a really nice pattern after the first week of December

there will be a 7-10 day relaxation around Thanksgiving due to the Pacific jet retracting, which is pretty well modeled once the jet extends late month into early December (you can see it strengthen late on the EPS here), this becomes a pretty classic look as the Aleutian low strengthens, AK ridging builds poleward, and the Scandinavian ridging retrogrades towards Greenland. the 50/50 and -NAO dipole is already beginning to show up

based on what, exactly?

it's a great match with PDO, MEI, general SST anomaly placement for ENSO - yes, 2010-11 was strong, but the placement of the anomalies is just as important, and they're very similar. this Nina is also no slouch QBO is also a dead ringer. I can see this December going somewhat like that one in terms of blocking, but that was a unicorn of a winter and to expect anything of that magnitude is foolish

it's second behind 2010-11 lmao which still remains a pretty good analog given how December might shake out

I do think the -EPO is legit. big cold dump looks likely and the odds of you guys seeing some kind of wintry precip are good, especially towards NNE we should see a relaxation around Thanksgiving as the ensembles have been showing due to a -EAMT developing around the 15th... would lead to a Pacific jet retraction over the next several days however, ensembles are then showing a descending Siberian HP that would then spark another +EAMT late in the month, encouraging another jet extension and subsequent Aleutian low/-EPO look around the first week of December it's easier to see this occur with the 200mb jet... extension leads to the poleward ridging, then a relaxation due to retraction, and then you can see the Pacific jet strengthen in response to the +EAMT... would extend again over the next few days

yeah, this is a really solid jet extension from the +EAMT at the end of the run

It looks like there are some wheels in motion to lead to a pattern change later on in November... mainly the development of an +EAMT, a flip to +AAM, and hints of Scandinavian ridging. First off, the +EAMT: There is pretty good model agreement on anomalously strong HP moving over Mongolia and the rest of east Asia, which helps lead to a +EAMT. +EAMT events often lead to an extension of the Pacific jet and subsequent poleward ridging around Alaska. This is bolstered by the shift to +AAM in the tropics, which often builds poleward and encourages blocking a few weeks down the line... Scandinavian ridging is also beginning to show up on both the GEFS and EPS in the extended range. This can both help to disrupt the SPV, which is a possibility, but this shouldn't impact the pattern too much unless it couples with the troposphere. Also, notice the beginnings of an Aleutian low beginning to form - this is a result of the Pacific jet extension after the +EAMT begins to form. However, what's more important is that ridging in this area tends to retrograde towards Greenland like so: https://journals.ametsoc.org/view/journals/clim/33/7/jcli-d-19-0447.1.xml So, although the pattern to open the month will be very warm and quiet (enjoy the great weather!), I expect a flip to colder and more active weather around Thanksgiving once all of these pattern drivers really take shape, mainly with the Pacific jet extension around two weeks from now. The Scandinavian ridging often takes longer to retrograde. We want to see these signals move forward in time. The analogs that some have proposed for this winter also featured blocking early on (2000-01, 2020-21, 2010-11), so it's nice to see some pattern drivers support it! We shall see.

It looks like there are some wheels in motion to lead to a pattern change later on in November... mainly the development of an +EAMT, a flip to +AAM, and hints of Scandinavian ridging. First off, the +EAMT: There is pretty good model agreement on anomalously strong HP moving over Mongolia and the rest of east Asia, which helps lead to a +EAMT. +EAMT events often lead to an extension of the Pacific jet and subsequent poleward ridging around Alaska. This is bolstered by the shift to +AAM in the tropics, which often builds poleward and encourages blocking a few weeks down the line... Scandinavian ridging is also beginning to show up on both the GEFS and EPS in the extended range. This can both help to disrupt the SPV, which is a possibility, but this shouldn't impact the pattern too much unless it couples with the troposphere. Also, notice the beginnings of an Aleutian low beginning to form - this is a result of the Pacific jet extension after the +EAMT begins to form. However, what's more important is that ridging in this area tends to retrograde towards Greenland like so: https://journals.ametsoc.org/view/journals/clim/33/7/jcli-d-19-0447.1.xml So, although the pattern to open the month will be very warm and quiet (enjoy the great weather!), I expect a flip to colder and more active weather around Thanksgiving once all of these pattern drivers really take shape, mainly with the Pacific jet extension around two weeks from now. The Scandinavian ridging often takes longer to retrograde. We want to see these signals move forward in time. The analogs that some have proposed for this winter also featured blocking early on (2000-01, 2020-21, 2010-11), so it's nice to see some pattern drivers support it! We shall see.

regarding Hunga Tonga, it actually looks like there is a correlation between years with a much cooler than average SH stratosphere and a -NAO early in the year the blog post that highlights this: https://www.severe-weather.eu/global-weather/cold-anomaly-stratosphere-polar-vortex-volcanic-cooling-winter-influence-fa/ this bolsters the analogs that myself and some others have in mind that show early blocking, like 2020-21, 2010-11, 2000-01, 2017-18, and 2021-22

2010-11 also had a severely negative PDO and it's actually a pretty solid analog, so, yes, I don't understand the gnashing of teeth about the topic right now no one variable is the end-all-be-all with seasonal forecasting

doesn't even need to be moderate! here's a composite of all central based Ninos, both weak and moderate... about as good as it gets from NYC southward the Februaries are basically weenie maps. even without Feb 2010 it's still a highly conducive pattern for cold and snow so, if we get that Modoki next winter, which I'm fairly confident of given general ENSO progression after multi-year Ninas as well as subsurface SSTs, it should be a big one

maybe next winter. like actually haha good shot at a central-based Nino

I'm including December and the start of January. yes, I know that the snowfall from those years might be paltry, but all that we can say is that the analogs point towards a 500mb pattern that should provide chances down to the Mid-Atlantic from Dec 1 - Jan 15 It's just that so much snow occurs in February, and since February looks to be a torch, you're going to get winters that end below normal

I'm honestly not really that sure. there is a chance that the next Nino could be strong, but that's obviously a shot in the dark at this point. I'm sure there's a lot of research being done on the super Nino and how it changed the atmosphere with the clippers, I think it's just some bad luck as well as a function of the pattern... the Nina composite doesn't really lend itself to clippers while the Nino one does

we've just been in a persistent Nina base state recently after the super Nino, which is why this stretch has been so mediocre for most over the last several years like pretty much everything in the atmosphere, it'll flip back around in time, and I'm becoming increasingly confident that next year will have the moderate Modoki Nino we've been waiting for from NYC southward look at all of the warm water waiting to emerge near the dateline! it's also quite common to see moderate Modoki events occur after multi-year Ninas (2009-10, 2002-03, 1986-87, 1977-78) here's a composite of all central based +ENSO events in the somewhat recent past and their Februaries: so, yes, it's coming. just have to be patient! I also agree with (and have been agreeing w/ for a while) @40/70 Benchmark that the start of this winter will hold some surprises. early-season blocking is favored by analogs like 2000-01, 2020-21, 2017-18, 2021-22, and even 2010-11! and yes, I know there was some bad luck here with 2010-11, but you guys would roll the dice with that 500mb pattern every single time

also

yeah I do think that the first couple weeks of Jan could be good snow wise if the blocking does come to fruition. after that Nina climo almost overwhelmingly takes over into Feb in the analogs it's never a complete shutout up by you guys, but it definitely looks torchy

December into early Jan still looks good... there's a legit signal for blocking, particularly in the NAO region I do agree that it looks gross as we head into Feb though

whoops. it's actually even stronger lmao

I haven't seen anything peer reviewed or anything like that... just a correlation that could be useful for this winter it seems like a bit too much to be a coincidence. there's a lot of years there and actual analogs based on ENSO/QBO/PDO that back it up

1) I believe they're years that exhibited significant SH strat cooling, not particularly for eruptions the author of the post constructed a SH strat temp index and picked out particularly cold years... here's the link if you'd like to read the entire thing, it's quite detailed: https://www.severe-weather.eu/global-weather/cold-anomaly-stratosphere-polar-vortex-volcanic-cooling-winter-influence-fa/ 2) yes, these are analogs that my coworkers and I agreed on, factoring in ENSO, PDO, and QBO... all of them are weak -ENSO/cold neutral coming off of multiple -ENSO events, besides 1996-97

it's also worth noting that the analogs also had a very weak NH SPV compared to average, which checks out with increased early blocking