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  1. Yeah, the continued -AAM state remains an interesting variable. It doesn't seem that Hagibis and the ongoing +EAMT are going to shake us from the long-lasting -AAM yet. I think a few interesting things are happening affecting the North Pacific pattern recently (and therefore the SSTs up there), leading to questions that likely will work out over the next several weeks or so. Tropical forcing has been strongest over Africa and the western Indian Ocean where there's been a standing wave over the last few weeks and much weaker over the central/eastern Pacific as the +IOD seems to be dominating...this after forcing was much more prominent over the central/eastern Pacific into the first half of September. Though this paper focuses more on Indian Ocean forcing's impact on the winter strat PV, it's worth mentioning that the mechanism they identify as the Indian Ocean destructively interfering with El Nino's warming effect on the strat PV in winter is the Indian Ocean forcing generally weakening the Aleutian low and +PNA: https://www.researchgate.net/publication/305510008_A_decomposition_of_ENSO's_impacts_on_the_northern_winter_stratosphere_Competing_effect_of_SST_forcing_in_the_tropical_Indian_Ocean This may help explain the recent struggle to add positive momentum and lack of a persistent low near the Aleutians, causing troughs to dive in close to the West Coast and cooling the waters there recently along the eastern edge of the blob. I would contend that the current Indian Ocean forcing would teleconnect better for central and eastern North American cold in winter with longer wavelengths, and also that I think we see Pacific forcing try to make a return before winter. The last 30 day anomalies are interesting (and, while not optimally placed right now, fairly blocky). I'd theorize that in winter, the low anomaly located west of the Dateline would be a little bit farther southeast (though not necessarily a robust Aleutian low) and the positive anomaly over Alaska and the Aleutians would also be farther east, closer to the west coast of Canada and into eastern Alaska...this is sort of backed up by the Phase 1 MJO composites from the CPC, with the ASO composite showing a ridge over AK and trough over the NW US and the DJF composite showing a somewhat weak low south of AK and more robust ridge over western N. America: Now, phase 8/central Pacific forcing in winter has a much more robust Aleutian low and +PNA (along with a -NAO, which the Phase 1 composite does not have at all): Obviously, these are two different Pacific patterns (even if both are cold for the eastern U.S.) with more significant downstream differences over the N. Atlantic and Europe. With last month's westerly wind burst and downwelling Kelvin Wave over the central and eastern Pacific, along with a continued -SOI and forecasted westerly wind anomalies from near the Dateline east over the next 10 days, the recent trend towards a Modoki El Nino seems to be continuing. The one hang up is that Nino 1+2 remains very cold, and likely won't warm substantially for a while, which could quickly work its way west if the wind/pressure pattern in the tropics changes drastically (which seems unlikely soon, but we have a long way to go). The upshot is if Nino 3.4 and 4 remain warm, the very cold Nino 1+2 will make anything resembling a basin-wide Nino hard to come by for the next few months. The IOD will remain strongly positive for a while, though climo and guidance do suggest it weakens during the winter. There's always some lag between SST changes and atmospheric response, though the EPS and CFS remain insistent on at least some increase in central Pacific forcing within the next few weeks with the western Indian Ocean forcing persisting, but weakening some. With recent warming in Nino 4, 3.4 and 3 that likely maintains in the near term, this does seem reasonable. That could finally add some momentum and perhaps encourage an attempt at an Aleutian low. The 12z Friday EPS also appears to have at least some signal for both an East Asian and North American +MT in about two weeks, though yes, that's very far out and certainly can change. My guess is we do see at least an attempt for a more Nino-like extra-tropical response at times later November into December, and potentially into winter if recent warming in the western Nino regions continues...whether or not that times properly with an MJO wave or mountain torque to develop a more traditional Aleutian low does remain to be seen, but I think there will be opportunities. Ultimately, at this juncture I have to agree that there is uncertainty in the Pacific with regards to whether we have a true Aleutian low with more of a +PNA look, if it's more of a -EPO (perhaps infringes onto both domains at times), or even infringes on the WPO domain given the conflicted tropical and extra-tropical signal right now. The signal that shines through over the last several winters, with a lot of different ENSO, QBO, and solar combinations in there is more of a -EPO than +PNA or -WPO, and that I don't think we've shaken this pattern yet as there's been nothing to truly shake it up (I'd like to think a strong La Nina in an easterly QBO would). That the composite of all of my analogs also has more of a -EPO than anything else, I personally have to think we see a -EPO at times. Obviously, you can still see an Aleutian low and +PNA with the ridge getting into the EPO domain...and recent trends that you mentioned cause it to be too early to rule out the ridging sneaking into the WPO domain. It does seem that getting central Pacific forcing and an Aleutian low may be most important to the Southeast U.S. (perhaps up into the Mid Atlantic), and also for Europe. Without it, the PNA may be neutral to negative, with the eastern and southern U.S. at the mercy of the North Pacific ridging location/magnitude if they want cold forced well south. The analogs and MJO composites strongly say (with a couple of exceptions, such as 95-96 which did it in a borderline moderate Nina) that El Nino forcing would try to force an Aleutian low/+PNA and -NAO...the current Indian Ocean dominated forcing, if it continued, would likely shift the ridging to a more favorable position for the eastern U.S. than what it's been the last few weeks, but seems to significantly reduce the potential for a -NAO. Given the very strong +IOD and forcing there currently dominating the pattern, perhaps this is why the seasonal models have such a +NAO this winter overall. It seems like the next several weeks may tell us what dominates the Pacific domain...is ridging over the Aleutians, Alaska, or more western Canada/eastern Alaska...and also likely tells us what the overall phase of the winter NAO might be...as we should see if Nino forcing can make a return by then and hopefully see if the AAM trends more positively or not.
  2. I honestly don’t know exactly how each seasonal model initializes, though I do think the sun is incorporated. It’s likely a combined issue with small initizalizaton errors propagating foward in time and issues with oceanic/atmospheric coupling, stratospheric coupling, physics and resolution that causes seasonal models to fail, especially if there isn’t an overwhelming signal such as a strong El Niño. I do know a somewhat recent study said the CFS has an issue coupling the stratosphere/troposphere resulting in poor AO/NAO forecasts...I’d assume the ECM and UK are better, though their seasonal NAO forecasts are also poor. The UKMET’s -EPO is somewhat modest...and coupled with a -PNA and ++NAO there’s definitely room for a strong SE ridge. Verbatim, parts of the Midwest and New England would still probably do ok with that look. That said, I think the -EPO is much more robust than that even if the NAO is that positive (which I’m also skeptical of).
  3. Something like the UKMET isn't far-fetched if the NAO is positive this winter. It has a ridge over the NE Pacific, and would likely verify colder from the northern Rockies to the Great Lakes than the model implies, but would be up/down over New England, Ohio Valley and the northern Mid-Atlantic (averaging mild as a whole) and warm over the Southeast. It's the same pattern we've seen a lot since 2012-13 as discussed on the previous page, but without big blocking to push the cold anomalies farther south. The NAO forecast this winter is something. One of the prominent methods will be very wrong. Analog/statistical methods generally point to a -NAO, while the dynamical models (with the occasional exception of some CFS/CANSIPS runs) point to a positive to strongly positive NAO. Given the analogs and general blocky nature of the pattern over the last few months, it "feels" like we'll see more blocking this winter than the UKMET has, but I would say confidence is much higher in a -EPO than a -NAO until the NAO goes negative and stays negative.
  4. I was curious if the typhoon recurve and simultaneous +East Asian Mountain Torque would be enough to shake us out of the -AAM state we've been in since the end of June...the mid-range models and ensembles are a resounding no with a parade of mid-latitude ridges persisting, which is a decidedly -AAM look. As has been discussed, that likely increases the potential for an earlier flip to winter (which has arguably started in the Plains/Rockies) as La Ninas/-AAM years tend to have colder Decembers than El Ninos. With that said, the tropics to continue to look Nino-ish with forcing over the western Indian Ocean, and per the CFS and to an extent the EPS weeklies re-developing over the central Pac by November. I'm guessing the end result of this is we get early cold (November/December) driven by a -EPO. The analogs with Nino forcing generally have a more -NAO through the winter than those that don't, many developing the -NAO by December...we have that forcing in the tropics, but I'm curious to see how the extra-tropical pattern that looks to remain -AAM/La Nina-like interacts with that. Either way it seems unlikely that the US is completely devoid of cold anytime soon, and as wavelengths quickly get longer over the next several weeks that will dump into the eastern U.S. more frequently. Also be careful with the EPS, it wreaks of the mean of 51 wavy solutions cancelling each other out in the mid-range...the pattern will not be zonal like it has (though the mean trough may still be over the western/central US like it's had, just a lot deeper than the mean would suggest)
  5. There was an Aleutian Low in October of 1995, and that year of course flipped the NAO for December. That fall had nearly opposite forcing from the composite of the analogs on my list that had a -NAO December, with sinking motion near the Dateline that fall (it was a borderline moderate La Nina, so no surprise), but still flipped the NAO for the start of winter. With the strong sub-surface warming occurring recently and continued +IOD and weak Nino-like forcing in the tropics, this analog has fallen a bit more out of favor with me (still in my set but not a "top analog"), but is an example of a low near AK in the fall occurring prior to a -NAO December among the larger analog set. The strongest velocity potential anomalies in September ths year were over the East Pac, with a max developing over the western Indian Ocean/Africa late September into what looks like most of October. The CFS and to some extent the EPS weeklies suggest Dateline/east forcing returning in a few weeks. 02-03 is an interesting fall tropical forcing (Sep-Nov) and QBO match to this fall that wasn't on my original list due to coming off of a moderate El Nino into the winter that may be worth more serious consideration if we can warm at least Nino 3, 3.4 and 4 a little more over the next several weeks. Yes, that October had a more classic Aleutian low than 1995 or what we'll likely see in a week or so (which looks like more of a Gulf of Alaska low). The two best QBO matches per the graphs posted above led to weenie winters with fairly different ENSO's ended up having a lot of blocking...break pumping is of course advised this early but I think if Modoki-like forcing can hang on through a good portion of this winter that there are more than a few analog years that support it being blocky over the North Atlantic. Of course, if forcing doesn't re-establish near the Dateline like the CFS tries to do by November and the IOD weakens during the winter, a warmer risk still crops up for the east...a few analogs had February as the coldest month while some others had a torch, which is fun trying to sort out.
  6. To piggy-back off of the above posts...The analogs that end up blockiest over the course of the winter have an Aleutian low and Niño-like tropical forcing in the fall. With the recurving Tyhpoon (coincident with a strong East Asian Mountain Torque) shocking the extra-tropics into a higher AAM/more El Niño-like regime, snow cover advance over Asia supporting continued descending Siberian highs/mountain torques through the fall, and strong sub-surface warming in the central Pacific recently, it looks good at this point for a blocky winter IMO. (Don with good points below as well...it’s certainly early)
  7. Right, I wasn't trying to draw any broader conclusions, just stating it was a -NAO even if it's not exactly traditional/most optimally placed for the NE.
  8. That’s a strongly west-based -NAO, but not a particularly helpful one for the NE US.
  9. Right now they're one in the same. So yes, the first is temps (Dec-Feb), second is precip (Dec-Feb), and third is snowfall (any snow that falls), I'll add that to my post so it's clear. Although the average of those 3 (and also of the larger set) is colder than what I have at this point, there are a few years in there that are noticeably warmer (including 04-05). I can see how the pattern turns warm for a time mid-late winter...and when you consider our 30 year averages in the context of a slow background warming, we are in one of the last couple of years using the current 1981-2010 normals that we were already warmer than when they became the new normals earlier this decade...basically, the default is a little bit above average, and you need a truly cold pattern to average cold for an entire season. The potential is there for significant and potentially prolonged cold, but until I'm more confident we don't turn mild or warm for a time in January or February I'm going to be cautious with forecasting below average temperatures for the winter as a whole. I'm definitely not dismissing the potential for very cold weather or even the winter to average cold as a whole into the I-95 corridor, but I'm "hedging" I guess at this point.
  10. Thank you for the comment and feedback @Snowy Hibbo That is an interesting point...it can't be denied that the extra-tropics have been in a Nina-like state since the end of June with a strongly, persistently low GLAAM. On the other hand, the Tropics still have been in more of a Nino-like state, evidenced by the Chi anomalies and other indices such as the SOI (some of that undoubtedly aided by the growing +IOD). A Nina-like state in the extratropics is not necessarily bad for North America, as Ninas are definitely colder in most of Canada and the northern US than El Ninos (on average, of course), and it can be argued that the forecast temp map I posted would resemble a La Nina more than an El Nino with the coldest weather focused over Canada and the northern US. Anecdotally, it seems that Ninas are often cold in December and warm in February in the eastern US (with Ninos seemingly the opposite). I wonder if that tendency, along with some suggestion of convection being most active in the central Pacific/western Indian Ocean in fall/likely at least early winter if nothing changes, aids in the potential for an earlier start to winter in the central and eastern US? I also wonder if that same tendency increases the warm risks at some point mid-late winter, if the +IOD weakens and we lose the Nino tendency in the tropics, perhaps allowing convection to become more favored over the West Pac warm pool at a time when the risk for stratospheric warmings will be higher. It definitely seems like the interplay between the Nina-like extra-tropics and lingering Nino in the tropics may be a large/perhaps the largest point of uncertainty at this point. A number of analogs pulled off very cold winters with a similar interplay, so again, it's not necessarily bad.
  11. These maps have been released publicly via video, so I’ll go ahead and post them here with a somewhat more technical explanation and commentary on what I’m thinking and where I’m most worried: Temperatures (December-February) Precipitation (December-February) Snowfall (entire season) Since I’m using the maps I created at work on company time, I’ll “plug” our YouTube video…I take no responsibility for the uh clickbait-y thumbnail or emojis that pop up in the video, but the maps, anything in this post, or anything I verbally say in the video are all fair game to comment about. Here’s the link to the video (the intended audience is the general public, so very minimal technical talk)… https://www.youtube.com/watch?v=ehVCUa24XCQ As for the discussion, the general ideas used earlier in September to gather some analogs still largely hold…those ideas were: ENSO: Neutral, though can allow for weak El Nino or weak La Nina if the year featured warmer waters near the dateline. Extra preference if coming off of a weak or moderate El Nino the prior winter-spring. PDO: Neutral or positive (it's positive right now though not strongly) QBO: Positive trending negative, expecting the 30mb winds to flip to negative at some point in the early to mid-winter Solar: Minimum Indian Ocean: Positive IOD in the fall, can trend downwards during the winter Off-equator Pacific SSTs: A positive to strong positive PMM (it's very positive right now), with more weight given if it stays positive through winter Atlantic: Neutral or positive AMO (it is positive right now though not strongly) Tried to find matches based on similar tropical forcing in mid-late summer as this year, though not as strong of a weight. Tried to find matches based on years with significant spring/summer high-latitude blocking, though was not as strong of a weight. As a reminder, the analogs were: 1958-59, 1966-67, 1969-70, 1978-79, 1980-81, 1985-86, 1990-91, 1993-94, 1995-96*, 2003-04, 2004-05*, 2013-14*, 2014-15, 2017-18, with starred representing the highest scoring matches when considering all of the above and getting double weight. That 500mb composite map for DJF looked like this: The big stand out features in the analogs were: significant potential for a –EPO, a somewhat +PNA favored with the Aleutian low displaced to the south, mixed NAO signal though at least some potential for a –NAO, and decent potential for a –AO over the course of the winter. The strong signal for a –EPO along with some signal for a –AO does imply increased potential for a cold winter in much of central and eastern North America, with the +PNA favoring a mild winter along the West Coast. Just looking at the various drivers on their own…a neutral or weak ENSO (likely warm neutral with warmer waters near the Dateline), very +IOD this fall, +PMM, +PDO (that has seemingly trended more positive in September, we’ll see what the monthly value is), descending –QBO with a lingering +QBO in the lower stratosphere, solar min, and the “low pass/lower frequency” signal this summer looking somewhat Nino-ish still with the strongest chi anomalies over the central/eastern Pacific, you get an interesting picture. The lingering +QBO and strongly +IOD/Modoki-ish look, along with the ongoing signal in the tropics late summer/early fall, support the most active convection occurring outside of the West Pac warm pool (so, outside of phases 3-6 of the MJO) heading into winter…meaning it would be most favored/active in phases 8, 1, and 2. We already are seeing this now, with tropical forcing most active over Africa and the western Indian Ocean, with some of the longer range models (EPS and CFS) showing signs of life over the central Pacific in a few weeks. Here is a look at the "low pass" signal via velocity potential/chi anomalies since July 1st: Here are the CPC's 200mb height composite anomalies for phases 8 and 1 of the MJO in December-January-February: During winter, phases 8/1 of the MJO are both cold. The analogs are overall somewhat chilly for December in the central/eastern US (though in general, January and February are the coldest months compared to normal in the composites), and this is generally done via PNA/EPO ridging in December in the analogs with a +NAO for December in the mean. Interestingly, a Phase 8 MJO in DJF strongly favors a –NAO…given the lower frequency signal appears to involve over the western Indian Ocean, Africa, and the central/eastern Pacific, perhaps that’s why Paul Roundy’s low pass analogs show a strong –NAO signal heading into December: Phase 1’s composite looks more like the analog composite for December, with any cold coming from PNA/EPO ridging more so than a –NAO. Given the propensity for a –NAO over the last several months, SSTs in the tropics potentially favoring convection in an area that teleconnects to a –NAO in winter, and current low-pass signal analogs also suggesting the same, it seems there are multiple signals pointing to the possibility for NAO help as early as later in November and December. The analogs and tropical SSTs, along with to some extent the same low-pass analog posted above, also suggest potential for a +PNA/-EPO as early as later November or December. Quick Siberian snow cover advance, favoring a stronger Siberian high and positive East Asian Mountain Torque events and subsequently an Aleutian low may also enhance the potential for a +PNA/-EPO to start winter. Several well-respected long range forecasters have mentioned the potential for winter to “start early” this year in the eastern U.S. (and if the NAO is involved, Europe) compared to most recent winters…if the tropical signal (driven by the strong +IOD, lingering Nino 4 warmth, and to some extent the +PMM and AMO) is not strongly disrupted at the wrong time by intra-seasonal variability (such as an amplified MJO passage through phases 3-6, or a negative East Asian Mountain Torque), then there appear to be multiple reasons for optimism as early as late November or December, with some signal for both +PNA/-EPO ridging and perhaps a –NAO. Assuming the lingering +QBO in the mid and lower stratosphere, strong +IOD, Nino 4 warmth/+PMM, and cooler waters near Indonesia persist over the next few months, the “ingredients appear to be in place” for less convection in the West Pac, suggesting a lessened risk for a destructive MJO passage. We’ll see how the tropics signal plays out as we head deeper into fall. Heading through winter, a big potential source of uncertainty will be what happens as the –QBO continues to descend in a deep solar min and the +IOD presumably weakens (which is climo for northern hemisphere winter). Unless a stronger move back towards El Nino occurs this fall (still not ruled out with the warmth near/west of the Dateline, though if this occurred it’d very likely only be a weak El Nino), a weakening +IOD and any strat warming events (which may become favored during mid-late winter assuming the –QBO continues to descend when combined with the solar min) may increase the risk for a more amplified MJO in the “unfavorable phases.” So, there likely remains some warmer risk in the eastern U.S. in particular for mid-late winter. On the other hand, if upward motion remains most persistent in the central-eastern Pacific or western Indian Ocean/Africa, then it’s more likely that any warmer intra-seasonable patterns would be mitigated. If a strat warming event occurred, there may be additional risk for –NAO blocking later in winter. It bears noting that the monthly analog composite mean has a +PNA/-EPO through March (strongest in January) along with a more –NAO in all three months (compared to December when the composite NAO is positive), with January also having the most –NAO out of JFM (February a close second). Beginning to tie this into the maps…comments on the temperature: It seems very likely that the Great Lakes and Upper Midwest see a cold winter based on the analogs and presumed tropical signal favoring a –EPO and +PNA this winter. It conversely seems very likely that the West Coast is mild. The East Coast is a mixed bag…perhaps due to being snake bitten last winter, and remembering mid-January-February of 2018, I had a hard time bringing the below average temps for the winter too far southeast. I’m worried a somewhat brief (a couple-few week) period of very mild temperatures is possible due to climatological weakening of the +IOD during winter, and increased potential for strat warming events, both of which may favor an unfavorable MJO passage in the middle of winter. However, it can conversely be argued that barring an intra-seasonal very mild pattern that something can argue for colder weather at nearly all points in the winter (and early spring) in the eastern U.S…so if the cold signals trend stronger heading into fall, I may end up bringing below-average temperatures farther southeast. As for the Southeast U.S., due to similar reasoning I currently have somewhat mild temperatures for the winter as a whole, though there is a strongly implied risk for EPO-induced cold shots that can bring wintry precipitation into the Deep South even if the winter averages a bit warmer than average. As for snow/precip…the analogs strongly suggest a wet/active winter from the Ohio/Tennessee Valleys into the northern Mid-Atlantic and New England. I couldn’t think of a good reason to deviate, though if things trend much colder in the east it would inherently trend drier. The analogs are also generally dry to very dry across much of the southern U.S., especially in Texas. A –EPO would suggest an active northern stream into the Plains, keeping precip from ending up too far below average and likely favoring above-average snow in the Upper Midwest, parts of the Plains and the eastern slopes of the Rockies. The analogs are very dry in the Pacific Northwest and couldn’t find good reason to deviate. Conversely, they lean dry for California and the Southwest but not as strongly as the Pac NW…with a lingering +QBO and El Nino influence to start the winter, along with a very +PMM, there is definitely potential for precipitation/mountain snow in California and the Southwest, especially through the first half of winter. For now went near normal precip/mountain snow in that area…may need to trim the below normal in the Dessert Southwest and perhaps consider above-average for parts of California if the lingering El Nino signal persists through the fall. That's all I can scribble down at the moment...I'll certainly check back occasionally for any discussion! Moving forward, I'll be continuing to tweak analogs while also trying to get a grasp on what the tropical/stratospheric signal is as we head deeper into fall for a better idea on what it will be in winter.
  12. Those are some pretty saucy tweets from Anthony. Usually he leaves a bit more to the imagination.
  13. 2004-05 is my favorite winter and I still don’t know how so many areas got so much snow looking back at the temp and 500mb means for that winter. I lived near CLE then. and that’s their snowiest winter by a mile. I’d obviously be ok with something close to any of the 3! Thanks for the comments Tom! Our social media guys enjoy posting those outlooks for various reasons on every one of the platforms they’re on, so I’ll be able to post parts of it here/publicly after it goes out to the clients. I was snake bitten last year myself and wasn’t happy with how long it took me to correct after the SSW, and definitely felt that shows how important it is to consider everything and try to properly weigh it as you said. The analogs certainly are very encouraging for a cold winter and some of the various factors on their own are too...but this early it’s important to try to see what can swing things either way and watch for them. I agree that almost anything can be legitimately argued for this winter if you want to.
  14. Playing with some analogs right now...here are some analogs, discussion, and caveats, focused mainly on the U.S....FWIW, my temp map for work is not as cold as this analog composite would imply and allows some risk for a SE ridge to crop up should things trend too far in the wrong direction (read below). Here are my key assumptions when looking for analogs right now...the analogs used to compile the attached 500mb map were found by subjectively rating every possible analog on each of the following criteria. Ultimately I give ENSO, PDO and QBO the most weight along with the solar cycle, though all of these are considered. ENSO: Neutral, though can allow for weak El Nino or weak La Nina if the year featured warmer waters near the dateline. Extra preference if coming off of a weak or moderate El Nino the prior winter-spring. PDO: Neutral or positive (it's positive right now though not strongly) QBO: Positive trending negative, expecting the 30mb winds to flip to negative at some point in the early to mid-winter Solar: Minimum Indian Ocean: Positive IOD in the fall, can trend downwards during the winter Off-equator Pacific SSTs: A positive to strong positive PMM (it's very positive right now), with more weight given if it stays positive through winter Atlantic: Neutral or positive AMO (it is positive right now though not strongly) Tried to find matches based on similar tropical forcing in mid-late summer as this year, though not as strong of a weight. Tried to find matches based on years with significant spring/summer high-latitude blocking, though was not as strong of a weight. The analogs I went with for this exercise are...1958-59, 1966-67, 1969-70, 1978-79, 1980-81, 1985-86, 1990-91, 1993-94, 1995-96*, 2003-04, 2004-05*, 2013-14*, 2014-15, 2017-18. Stars denote highest scoring matches when considering all of the above and double weighting. Obviously some of these are very cold winters for the eastern U.S. and the composite look is cold. There is a strong signal for Alaskan ridging and a -EPO, which is not a warm pattern for the central and eastern U.S., though where exactly the cold dives in can make a difference for the eastern U.S. with more mixed signals on an NAO. A neutral-ish ENSO and +QBO to start winter aren't great signals for a -NAO, though the deep solar min is and the QBO will be improving through the winter. The SSTs up there support a -NAO, but aren't a strong forcing mechanism on their own. There is not a strong correlation between negative summertime NAO and subsequent winter NAO and the forcing mechanisms are different, so the persistent -NAO this summer doesn't really help or hurt. In terms of what to watch for in the eastern U.S. in terms of swinging warmer or locking in cold...I'll be watching to see if we hang on to the warm waters near the Dateline in the Equitorial Pacific and the +IOD as we head into fall. If we keep those we are more likely to see convection near the Dateline this winter which usually forces an Alaskan/western Canadian ridge. If we see a stronger push towards La Nina and lose the warmth near the Dateline, the risk for a more amped SE U.S. ridge increases...we don't need the Nino region 3.4 anomaly to be above 0C to have a cold winter in the east, but region 4 is pretty important and needs to stay warmer IMO. Based on the persistent -SOI and forecast generally weak trades over the central and western Pacific over the next week or so, there won't be a big La Nina push in the near-term, though the recent easterly trade surge did nudge things in that direction over the last couple of weeks and there's still a lot of time for that to resume. The waters near the Dateline and just west remain fairly warm both at and below the surface, and until that goes away some move back towards a weak Modoki El Nino also can't be ruled out. As we saw last winter, a SSW can really enhance tropical forcing/convection over the West Pac warm pool (which is usually warm for the eastern U.S.), so an initially +QBO and seemingly low risk for an early SSW may give some margin for error...but if the SST pattern becomes unfavorable between Australia and S. America for convection near the Dateline the pattern more likely supports eastern U.S. warmth this winter. The analogs that have an Aleutian low in October generally had much colder subsequent winters than the ones that have an Aleutian high and subsequent trough over western Canada in October. I'm aware of what the longer range guidance hints at to start October up there, but wouldn't lock it in yet. A continued drop of the QBO heading into the fall is also important for increased high-latitude blocking prospects as we head into winter and a lower risk for the Pacific jet to be too strong/zonal into the west coast, which would likely result in quite a bit of warmth for North America given how mild the entire Pacific is. An additional caveat is the northern hemisphere water temperatures from the tropics up to the polar regions where there was another near-record sea ice melt are ON FIRE. Do older analogs break down as we continue to warm? If so, how do things change? The warming baseline gives less margin for error (you probably don't luck into below-average or even average temps, you either have cold signals or you torch). Lots of food for thought...I definitely don't hate the prospects for a snowy winter from the Ohio Valley and Great Lakes into the Northeast, and the warm PMM and any remaining warm ENSO influence can bring some snow prospects to the mountains out west, but the pattern can turn warm quickly if we lose the warm equatorial waters closer to the Dateline.
  15. A little over 4” here in the lower elevations in NW NJ. Extremely picturesque paste still coming down moderately. Mixing line getting dicy for NYC and LI but whoever stays north of it is fixin’ to rip like mad. I think most of NYC can hold onto all snow the next couple hours as this heaviest surge pushes in...anyone farther SE onto Long Island will try to sleet. Let’s see what happens!
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