OHweather

There is some support for Chuck's teleconnection outcome... Moderate La Ninas which this one is have a nice -NAO signal, but with a +EPO. The AO is close to neutral: This is a hybrid or basin wide La Nina...also supports a -NAO, but +EPO and AO: With that outcome, it'd generally be tougher to snow farther south, but would be an active northern stream and if ridging briefly amped into Alaska it'd get cold farther south and could snow. The -NAO keeps the Great Lakes and New England from torching. But, the descending easterly QBO may give some more hope (hybrid and east-based weak to moderate La Ninas with westerlies descending or easterlies...we have easterlies this winter): I like a -NAO this winter. I think the AO and EPO go positive at times, but also think we get a nice crack at a -AO and -EPO through December, so we could have quite a cold start before those trend more positive January and maybe February...then the SE ridge flexes more, but the NAO may hold off a torch in the Great Lakes and New England. That's kind of what I envision...Chuck's -NAO/+AO/+EPO could pan out for the season overall, but with a cold start and then still somewhat variable in the Great Lakes and New England, but milder farther south.

Are you thinking -NAO, -PNA, +EPO this winter?

I knew it couldn't be a good sign when I checked for the PNS and saw a damage survey from the October 21st tornado outbreak. Bands never got organized last night...kind of funny that the best accums in NE Ohio occurred during the day yesterday in Lake County when it was in the mid 40s outside of the bands...I saw a few pictures on Twitter of some light accumulations (maybe up to a few tenths) yesterday in Lake County.

Interesting little lake effect set-up tonight - Tuesday night for parts of NE OH / NW PA. As dta said, decent shot at flakes at the least. Beyond some graupel in heavier showers, it should be mainly rain through tonight with a W to WSW wind keeping activity confined to extreme NE OH into PA / SW NY. It becomes colder aloft on Tuesday with a W flow persisting, with a shortwave moving through late morning / afternoon from west to east, which may focus a couple of decent W-E oriented bands for a few hours and probably causes a few diurnal (non lake effect) showers to pop inland, which could fall as some sort of mixed precip. It should be too warm during the day for more than a slushy coating of snow or graupel in parts of NE OH / NW PA into SW NY, though will likely be cold enough for a decent amount of mixing in any heavier squalls or bands. Tuesday night is a little more interesting, with another shortwave moving through late-evening into the overnight from west to east across the lake. One or two more intense W-E oriented bands (along with orographic enhanced showers) should flare-up in the evening, and then at some point overnight shift inland and break up as the shortwave goes by and shifts the flow more NW'rly, and as drier air starts working in later in the night. With 850mb temperatures of -5 to -7C and 925mb temperatures of 0 to -2C through the night, it's close to cold enough to consider decent accumulations in the higher terrain where banding occurs. It's marginal overall, 1-2C warmer aloft than the October of 2013 event that dropped up to 8" in the eastern suburbs, but where banding and terrain combine to maximize potential there could be some localized accumulations of 1-3" in parts of NE OH / NW PA, along with the higher terrain of SW NY Tuesday night. With a well-aligned westerly or WNW flow Tuesday evening, lift from the shortwave, upstream moisture from Lake Michigan and extreme lake-induced instability, there could temporarily be the organization and intensity needed to drop some actual accumulations, especially in the higher terrain. We'll see what happens...flakes are a good bet, but there could be some localized but quick accumulations under any banding Tuesday evening into the night...particularly in the higher terrain from extreme eastern Cuyahoga into northern Geauga, inland Erie County PA and inland SW NY.

The EPS weeklies from yesterday...mid-November into the first half of December there's some cross-polar flow along with a -NAO. The Pacific side is less cooperative, but verbatim it'd be active and chilly enough to be interesting for a lot of the northern US and maybe into the central US at times. If the Pacific pattern ever amped, it could get pretty cold. Interesting run at the least. A lot of members have a weakened stratospheric PV as well.

I think it depends on where you are in the west. I think the Pacific NW, northern CA and the northern Rockies have a decent shot at a wet winter. Far from sold on that farther south though.

The Pacific jet is pulling back in the short term, briefly allowing for nice amplification over western Canada and a nice cold shot in early November... It's a decent shot and some areas may see flakes, but I don't think we're done with Pacific influence yet, as there's been agreement the Pacific jet rams into the West Coast again into mid-November. We won't completely torch as there will be more chilly air running around, and it will be an active pattern as that energy undercuts the ridge over Canada, but it will probably lean mild again into mid-November: Looking farther ahead, the low frequency forcing near 120E has drifted west into the Indian Ocean recently, and is beginning to constructively interfere with the MJO: Will the MJO be able to pull the forcing back east towards 120E (and perhaps a bit farther into the West Pac) in mid-late November? The EPS and CFS velocity potential forecasts are attached: In the fall and beginning of winter, tropical forcing moving into the western Pacific tends to suggest potential for blocking to develop in the short-medium term: I think November ends up being up and down and not that cold overall over the central and eastern CONUS...however, there will be a nice cold shot to start the month and an active looking pattern, so I'm not saying something can't come together right and snow somewhere. But, I think we have trouble sustaining cold through the first 20 or so days of the month. Tropical forcing working into the western Pacific mid-late November could signal an opportunity for a more robust pattern change that can bring more significant and sustained cold.

I like that the strongest cooling this month has been in regions 1+2 and 3, as 4 warms slightly. Steady cooling in 3.4. A trend towards either a basin wide or east-based La Nina, away from Modoki. The sub-surface loop implies this trend continues in the near future. Staying away from that central Pacific or Modoki La Nina look is a good thing for -NAO prospects this winter...

Yeah go for it!

Nice to see some lake effect precip in the forecast this weekend. I feel decent about CLE coming in with an above average snow winter for the first time since 13-14 (I know some other sites have done it once or twice since then, but it's been a pretty barren stretch after the 2000s were relatively "hopping" for snow)

Different way of coming up with these analogs and several different years, but interestingly a pretty similar look November-December and November-February overall as those. January and February differ a bit more from yours but still a pretty similar look and evolution overall...and with enough -NAO that I think most people would roll the dice with it. Curious to see if the October 500mb pattern ends up close to these analogs, NAO probably won't be as positive at the end of the month as these analogs...

2011 is one of my analogs, so I do think there are enough similarities to this year to consider it. However, I don't currently see a pattern as perilous as that year: While Oct 2011 had some similarities over the Pacific, this year will have lower heights out west and higher heights in the east, and won't have as positive of an NAO in October. Then in November 2011, the super +EPO and +NAO took over and ended any chance of sustained winter that year: I currently don't think this year can go as badly as 2011 went by November...but, it is still something to consider if the +EPO doesn't start relaxing into November. We'll know in a few weeks if we're going the way of 2011 or not.

Now that I'm home and glancing through the actual write-up and some of the composites I did while working on it, I didn't include 08-09 in the "better" QBO match sets I used because it was too positive at 30mb through the winter (which I think is the correct move, I was worried that I included it in those sets which would've been a little iffy). However, the point about the downwelling easterlies above lingering westerlies does still hold IMO...the research about North Pac ridging in La Ninas based on QBO that those such as Anthony Masiello and Griteater have done over the last decade revolves around that lower-strat QBO, so this winter and 08-09 would both fall into the positive lower-strat QBO La Nina camp that has more amped north Pacific ridging.

I can see that look playing out at some point mid-late winter if the ridging over the N Pacific is amped enough. The PNA should average negative so if / when the NAO goes positive we can get that look where it's cold west with a SE ridge in the east. As you alluded to we may not get a month that's quite that cold in the west but a couple of decent shots are certainly possible if not somewhat likely. I do hope that we don't go the way of what the mean of those winters looks like over the eastern CONUS, although outside of CA it's not as horrifically dry in the west which wouldn't be the worst thing in the world. 2011-12 scares me a little because it's quite a good ENSO match on the upswing portion of the solar cycle and a similar QBO to this winter. That year did not have as warm of a West Pac warm pool and had more convection occurred farther west over the Indian Ocean, which I don't *think* this year will do, but for eastern US snow lovers that's the kind of year that's a decent enough analog to scare you. 01-02 is off in enough other areas that it doesn't worry me, though it also was a ++AO winter. 67-68 was an interesting, blocky winter with a similar QBO to this year and I considered including it in my overall set of analogs...I ultimately decided against because it was farther back in time with a poor match in Indian Ocean / western Pacific SSTs and had more tropical forcing near the Dateline, which I don't think is likely this year.

^ For those wondering, when I saw how awful my hair looked like in that video yesterday I went and got it cut after work. Important point of clarification

I agree it's an issue, but there are some QBO similarities that I liked. It was positive at 30mb through the winter, but easterlies were beginning to descend through the stratosphere during the winter with westerlies persisting through the lower stratosphere. This year is certainly farther along in the process and I think that will be conducive to keeping the vortex weaker (especially early in the winter), which may help the AO and NAO compared to 08-09. But when I was looking for QBO analogs (and comparing to "opposite years"), I looked for years with descending easterlies in which westerlies hung on in the lower stratosphere into at least early winter (whereas for opposite years, I looked for winters with descending westerlies with established easterlies in the lower stratosphere). 08-09 is not a perfect match but is in that part of the cycle, albeit earlier on.

17-18 is a winter that comes to mind in terms of being mild overall across the south but still having a couple of snow events when it got cold. I can see it happening this winter that way too, though maybe not quite as noteworthy as what happened in early 2018 along the Gulf Coast.

I can see why the paper has 07-08 as hybrid. The DJF anomalies were quite cold west of 150W, which is why I called it a CP event, but the cooling in the fall was more basin wide. I think that event may end up being a bit more west based than this one (and certainly a good bit stronger which probably makes a larger difference) but I can see the reasoning for calling 07-08 hybrid. I agree that we aren't looking at an east-based event, which is why I'm a bit warmer in the south / east than a lot of those composites and included some stronger and CP events in the analogs, as long as they were decent matches for fall tropical forcing, solar, and / or QBO this year. I do think we likely stay away from an uglier look like 11-12 or 16-17 which were truly central Pacific based with their cooling.

Yes, the gist of that graphic was to illustrate that in general, second year La Ninas are usually more hostile than first year La Ninas (with all second year events on the left), but non-strong second year La Ninas (especially those with the cooler waters focused farther east) mitigate that to some extent (on the right). It comes down to if there's enough blocking to get one or two big shots all the way to the Gulf Coast...a lot of things point to that at the moment, but if the La Nina gets stronger or becomes more firmly central Pacific based we're run the risk of things looking more like the map on the left there.

I consider it "hybrid" right now, so not a true central Pacific event but it's not EP based either. If it trends towards moderate and the coolest water is pretty far west over the next month or so that could result in me pulling things in a warmer direction (especially in the south and east), especially if the pattern is looking more like those warmer analogs. Honestly I just went through each year and gave a designation based off of my impression of it (though most of them are the same as the paper). My reasoning for calling 08-09 a central Pacific based event was because the center of the cooling was firmly focused west of 150W, which is what the paper lists as the rough guideline, and because the eastern Nino regions never got that cool. I think it's firmly more CP based than this year (so far), though as you've alluded to probably didn't kill ruin the winter because it was on the weaker side. Despite this I think it's a good analog (second year La Nina, similar intensity, similar QBO, low solar, similar tropical forcing in the fall to what I currently expect this year) and is a double weight for me right now.

I remember you being all over the better blocking potential last year, so that's good to hear! The more seasonal outlooks one does, the more you realize that location of the ENSO (along with things such as QBO) are much more important than just "El Nino" or "La Nina", and the cited paper is definitely a great resource in La Nina winters. "Modoki" La Ninas aren't discussed quite as much as Modoki El Ninos but it arguably has as large of an impact, especially with non-weak events.

Thank you for your insight as always. A fair number of my analogs have a -NAO returning in March too...here's the mean 500mb pattern in my current analogs: I can see how the Plains or even Southwest get one or two big cold snaps this winter...the PNA will be negative at times (perhaps averaging negative for the winter) so if the EPO and AO stay positive some cold can get into the west.

My thought is that there's blocking early, probably peaking in December, and then it backs off a bit through January and into February with the cold shifting northwest and more of a gradient pattern setting up as the SE ridge flexes. So I think it is cold early in the GL/OV and then is milder mid-winter. Snow may depend on where you are...up in Wisconsin it may be most active when the blocking relaxes, whereas farther south gets more of their snow when it's colder with more blocking. I think by November we'll have a decent idea on if the early blocking idea will pan out or not. There is an element of "could go either way" still this early.

I like a winter with a fair amount of blocking (I think it'll average -AO overall) but also a somewhat -PNA. It's a La Nina so it'll be polar stream dominant and that'd be a chilly, active look for the sub-forum if correct.

It’s still a little early on in the game, but we’re getting to the point where we can start narrowing down what various “pattern drivers” may look like this winter and examine analogs and even some seasonal forecast guidance for clues. For those who just want the maps, here are my current thoughts on temperature and precip through the winter. I’m lumping March into winter because it’s a month that can still prove to be productive for snow for many areas, and because many analogs are chilly in March. The detailed write-up with reasoning, analogs, and a look at longer range seasonal models is at the linked blog post (I'm exhausted from uploading the images on there, so I'm only going to upload a part of the post here). I hope to follow up with more focused thoughts in November, time permitting… My guesses on teleconnections: AO: Solidly negative. NAO: Near neutral or slightly negative overall, possibly large swings EPO: Near neutral or slightly negative overall. PNA: Negative, especially later in winter A stronger or more central-Pacific La Nina could pose warmer risks, especially in the central and eastern U.S., as would a strong stratospheric PV early in the winter that’s coupled to the troposphere. A quick increase in sunspots could also be a warmer risk. If forcing ends up more focused farther west into the Indian Ocean it’d likely point to a warmer winter. The La Nina staying weak to moderate and more basin-wide would point to a chillier outcome with more blocking being more likely. A weaker stratospheric polar vortex early in the winter, and tropospheric blocking developing in November, would also point towards a chillier / blockier outcome. Scandinavian or Ural ridging in October or November would also point towards a chillier and blockier direction, as would sufficient tropical forcing occurring east into the Pacific at times. I expect a very up and down winter, with very cold air frequently available over Canada that occasionally works south into much of the central and eastern CONUS this winter, along with the Northwest. The Southwest will generally be milder with a somewhat weak sub-tropical jet. The southern Plains, Gulf Coast, Southeast and lower mid-Atlantic will probably lean mild due to sharp warm-ups when blocking relaxes and / or the PNA shifts negative, though a couple of periods of EPO-induced cold all the way to the coast are possible. The most persistent cold will be in the northern Rockies and Upper Midwest. The analogs really like the first part of winter (December into January, possibly starting to turn colder in November) for blocking and cold into the central and eastern US (with cold focused more on the northwest in February). The analogs have a -EPO, -NAO, and -PNA pattern in March. I’m optimistic about snow in the northern Rockies and Pacific Northwest, along with from the Great Lakes and Ohio / Tennessee Valleys into much of the Northeast and New England. Along I-95 from Baltimore to DC and Richmond, events will be rainy at times when blocking relaxes so snow will struggle to reach or exceed normal, though there should be opportunities for wintry weather when blocking is strong enough to suppress the Southeast Ridge. I do want to post some maps based on the analogs I'm currently rolling with... And FWIW, the analog pattern for October is pretty close to what's modeled this year: Anyways, the rest of the write-up and a closer examination of the analogs is here: https://jimsullivanweather.com/2021/10/04/an-exploration-of-cool-enso-winters-and-a-look-at-winter-2021-22/