Winter 2021-2022

[40/70 Benchmark]

15 hours ago, Mr. Kevin said:

Hi 40/70. I have a question. I read your final notes on last winter at 33andrain.com. If we get a weak niña and a -qbo this winter, do you think we can get a relatively cold winter this winter, all else being equal? I know its early, but I was curious what you keep an eye on for what type of winter could happen

Certainly....weak la nina and a -QBO is a pretty good combo for cold...however, what is also important is the structure of the la nina...ie, east or west based. This season's looks like it may be more west-based, which is not quite as favorable for cold. But wouldn't worry too much bc it should be weak.

[40/70 Benchmark]

13 hours ago, raindancewx said:

-NAO (DJF) winters (in aggregate): 1954, 1955, 1957, 1965, 1967, 1968, 1977, 1978, 1986, 1997, 2009, 2010, 2020. I would argue a year like 2000-01 or 1967-68 is more "-nao" in reality than a "fake" -nao year like 1997-98, but the point is, roughly half of years with rising solar since 1950 see a net -NAO in winter.

The "rising" but still low (<55 sunspots per month July-Jun) years are: 1954, 1965, 1986, 1997, 2009, 2010, 2020. That's seven for seven for a net -NAO, whereas the "rising" but high years are six for twenty. The odds are not bad overall even if you want to regress the 7 for 7 with the x+1/y+2 rule with some Bayesian assumptions, i.e. assume the trend would go from 7/7 to 8/9.

The 2021-22 July-June solar year is starting off with around 40 sunspots this month - going to be real interesting to see how rapidly solar rises this year. It's harder to predict than the decays from the peak solar I find.

Thanks for this...excellent post. Very much appreciated bc I am not well versed in the solar aspect. This looks favorable for a neg NAO, especially in conjunction with a weak ENSO. The only apparent mitigating factor is the potential modoki nature of this developing cold ENSO event.

[40/70 Benchmark]

19 minutes ago, Typhoon Tip said:

The problem with the NAO in this analysis - for me ... - is that it is not really physically motivated into modes by super sets of forcing ( such as extra-terrestrial/solar... ) nearly as readily as it is by planetary wave modulation taking place in vastly shorter time and spans of synoptic vagaries.

Start with the AO ( would be my argument; not meant as gospel  -)  The AO happens to share domain space with the NAO.  The circuitry is through the entire polar domain ...to then partially motivate the NAO toward base-lines when any offsets are absent.  Like, if the AO is negative, the NAO 'wants to be negative' because of that shared space, but the synoptic forcing is blurring that signal..  Thus, there is an influence on one another, but there is also a disconnect and they don't always share the same mode value, nor move in the same direction.  This tendency for skewing, combined with the fact the (-) vs (+) NAO states are heavily modulated by short duration planetary wave phenomenon, doesn't lend very well to a solar forcing or very reliable ( or perhaps "believable" ) useful as a predictor for the NAO. 

I just wonder/if not suspect, that replacing the NAO with the AO in the above analysis, might be better.

The other aspect is that the NAO is over-rated for the Lakes/OV/upper MA and NE regions.  It always has been.  There are times when it correlates to storms and cold and it seems like it's immovable.  But in reality ...the majority of our storms and cold are preceded by modulation events upstream in the EPO/PNA ...while there is -AO tendencies overall.  In fact, a data supported argument could be made that the NAO more oft then the other way around ..is a negative interference pattern.  It may reflect a correlation more in temperatures than actual storminess in said areas. 

Yea, they are in sync about 70% of the time, I believe....while I agree that many oversimplify it, I would rather have a neg NAO than not beneath the latitude of NNE...especially during a cold ENSO event when the Pacific may not be great. Finally, while the polar domain is certainly more stochastic in nature than the larger scale Pacific based teles, I think the prudent course of action is to err on the side of more influence with respect to solar considerations than less, since its just a pervasive influence about which so little is known.

JMHO.

[Typhoon Tip]

27 minutes ago, 40/70 Benchmark said:

Yea, they are in sync about 70% of the time, I believe....while I agree that many oversimplify it, I would rather have a neg NAO than not beneath the latitude of NNE...especially during a cold ENSO event when the Pacific may not be great. Finally, while the polar domain is certainly more stochastic in nature than the larger scale Pacific based teles, I think the prudent course of action is to err on the side of more influence with respect to solar considerations than less, since its just a pervasive influence about which so little is known.

JMHO.

That's my point ... yeah.   The "polar domain" as a whole is more important in said solar connection then the NAO sub-space that is modulated too much by synoptic vagaries.

Guess I could have just said that - heh.

As far as the 'rather have neg NAO' to each his own on that.   I have done my own study and the majority of significant events were not associated with NAO's that were < -.5 and were in fact, rising at the time or within a week of significant event passage -

which makes sense anyway, because the storms bring there bag of negative heights up there into the graveyard and that sends the NAO up in index mode, while it translates through..etc...

Circling back the first sentence concept:  in the exmple, the NAO just got sent through a modality that had nothing to do with solar. 

That 70% thing though ...I wonder, would the 70% improve(reduce) percentage when time lags is applied.  

The reason I ask is a basic model inference:  The AO drops --> the westerlies descend in latitude -->  blocking nodes evolve above the ring of the westerlies in the WPO-EPO-NAO regions ( Eurasia notwithstanding...).  But that all takes time... who knows how long.  It may even vary therein.  Like the AO could be triggering this, but the these sub-spaces still haven't responded ...and on and so on. 

Or, maybe time lag is already considered in that 70% in this is an unnecessary question -lol

[40/70 Benchmark]

42 minutes ago, Typhoon Tip said:

That's my point ... yeah.   The "polar domain" as a whole is more important in said solar connection then the NAO sub-space that is modulated too much by synoptic vagaries.

Guess I could have just said that - heh.

As far as the 'rather have neg NAO' to each his own on that.   I have done my own study and the majority of significant events were not associated with NAO's that were < -.5 and were in fact, rising at the time or within a week of significant event passage -

which makes sense anyway, because the storms bring there bag of negative heights up there into the graveyard and that sends the NAO up in index mode, while it translates through..etc...

Circling back the first sentence concept:  in the exmple, the NAO just got sent through a modality that had nothing to do with solar. 

That 70% thing though ...I wonder, would the 70% improve(reduce) percentage when time lags is applied.  

The reason I ask is a basic model inference:  The AO drops --> the westerlies descend in latitude -->  blocking nodes evolve above the ring of the westerlies in the WPO-EPO-NAO regions ( Eurasia notwithstanding...).  But that all takes time... who knows how long.  It may even vary therein.  Like the AO could be triggering this, but the these sub-spaces still haven't responded ...and on and so on. 

Or, maybe time lag is already considered in that 70% in this is an unnecessary question -lol

No, no....I agree that modularity is more important than mode...you want mass flux, and this is what is paramount for major cyclogenesis...of course. All I meant was that you want it rising from -.5 and not +1, or else you run a much larger risk of precipitation type issues.

We more or less agree.

[Mr. Kevin]

2 hours ago, 40/70 Benchmark said:

No, no....I agree that modularity is more important than mode...you want mass flux, and this is what is paramount for major cyclogenesis...of course. All I meant was that you want it rising from -.5 and not +1, or else you run a much larger risk of precipitation type issues.

We more or less agree.

I appreciate your response to my question 40/70. I dont believe many people got last winter ao/nao being that negative, considering being in a +qbo. I know more factors are always considered when it comes to winter. I would like to see a few years of a -nao west based. I do wonder 40/70, if the niña wasnt as strong as it was last winter, would it have been colder?

[40/70 Benchmark]

17 minutes ago, Mr. Kevin said:

I appreciate your response to my question 40/70. I dont believe many people got last winter ao/nao being that negative, considering being in a +qbo. I know more factors are always considered when it comes to winter. I would like to see a few years of a -nao west based. I do wonder 40/70, if the niña wasnt as strong as it was last winter, would it have been colder?

I was pretty close, but averaged slightly more negative than I forecast. I was right about the first neg NAO DM month since March 2018, though.

Odds are that a weaker nina would have been colder, but not necessarily....especially in the middle of the country, as it was very cold there. If it were weaker and  more modoki like, it could have even been warmer...bottom line is that there are so many other factors at play that you can't say definitively, but on average they weaker they are, the colder they are.

[raindancewx]

My interest in looking at the NAO is mostly from a national temperature perspective rather than identifying periods for Nor'easters or something. In that sense, it is most useful from about mid-January to mid-April. For Nov-Jan, the AO is more important in terms of long-term correlations.  For precipitation, the NAO actually has some pretty strong correlations in various places too. The WPO is actually pretty useful in Sept-Nov, and then in Feb-Apr for temperature patterns too, in a correlation sense. Locally, the +NAO/AO is actually a good signal later on if it happens in November from what I can see.

The seven winters with 'rising' but still low solar are all -AO winters too, if that's your preferred measure. November NAO values are a good long-term indicator here for how wet late Spring will be, but otherwise it's not that useful until later in winter for national patterns for temps/precip. The long-term WPO correlations on the other hand correspond almost perfectly to some of the wild temperature pattern swings in the Fall and Spring in the past year.

My point with the NAO/AO stuff isn't that I can see with 100% certainty that they'll be negative this winter. It's just we're nearing the end of the historical 'solar' time frame when odds of a -NAO winter are likely. To me it's worth figuring out whether we'll have one more winter with an extended -NAO/AO before we predominantly switch back to mostly positive NAO/AO winters. New Mexico is uniquely weird in that we get our top snow years in both the highest NAO/AO and lowest NAO/AO winters. So I'm actually pretty indifferent about what ends up happening typically, since most years are relatively neutral. 

You could see solar activity rise from 16 sunspots/month to 30, about the level of gain from 2019-20 to 2020-21. Or you could see it rise to 68 or something if we're going into a bigger cycle (more active sun) than last time. In the latter case, there is no particular signal in the solar data. April 2021 NAO was also negative like April 2020, which hadn't happened in forever prior to 2020, so that was my first tip off to pay attention to it again this year.

Most people seem to use Nino 3.4 as an estimate for what the PNA is going to do, even though the correlation is ~0.3 r-squared for DJF, and much weaker in December. The Nino 3.4 to PNA correlation in August is literally stronger than December to Nino 3.4 for the PNA, so I always find the way it is used to be a bit strange. The image below actually supports a La Nina though, as the PNA correlation to Nino 3.4 is negative (+PNA = -ENSO) long term.

https://psl.noaa.gov/data/correlation/table/corr.table_dec.txt

https://psl.noaa.gov/data/correlation/table/corr.table_jan.txt

https://psl.noaa.gov/data/correlation/table/corr.table_feb.txt

[George001]

I have been looking into it a bit more and not only is the temperatures in the enso region (both surface and subsurface) starting to decrease, but tropical storm activity and the SOI is increasing. Both of these things indicate that the atmospheric pattern reflects La Niña. The Enso 3.4 region being down to -.5 degrees below average already in late July would put us on track to follow the coldest members of the cfs v2 enso forecast ensembles. The mean right now for that model is roughly -.8 in the enso 3.4 region, however by now the mean had us at roughly -.3 in the enso 3.4 region and we are at -.5. Many of the ensembles in the cfs v2 model that have us at -.5 by now take us to a moderate La Niña. With how the atmosphere and subsurface look combined with the trend of the models with each update increasing the strength of the La Niña forecasted for winter, I would not be surprised if the La Niña is already at moderate strength by September, potentially increasing even more and becoming stronger than last years La Niña. I know I said I was thinking -.8 to -.9 was likely before but looking at the latest data I’m starting to believe we could see a peak of -1.2 to -1.6 in the fall. 

[Ginx snewx]

Sign me up

[George001]

2 hours ago, Ginx snewx said:

Sign me up

It looks like there is good North Atlantic blocking and oddly enough it brings us to a weak El Niño for the winter. I don’t like the western pacific ridge that far west though, that to me looks like the the Jet stream configuration would favor the Midwest and north west areas of New England like Buffalo for severe blizzards. However, the pacific jet appears to be average strength which is MUCH better than we have had in the last few years, which would give us more room for error in regards to storm track. Due to the severe North Atlantic blocking combined with a more north and western storm track, that screams miller b pattern where yes, lows will go to Buffalo and at times even Wisconsin, yet due to the severe North Atlantic blocking, the low redevelops under Long Island and just crawls up the coast. This pattern is no slam dunk 2014-2015 pattern, but it does have a very high ceiling with the potential for Miller b lows to just hit a wall and sit there right over cape cod, bringing a severe blizzard from NYC to eastern Maine. It’s a strange pattern for an El Niño, to me it looks more like a favorable strong La Niña pattern with severe North Atlantic blocking+ limited pacific jet+ farther west polar vortex intrusion and western pacific ridge over Alaska instead of western North America. That look reminds me of 2010-2011, although I would be very happy with a weak nino I don’t buy that at all, I strongly believe there will be a La Niña, possibly even a strong one.

[George001]

This is a bold call but after looking at the latest subsurface data and the atmospheric pattern in place, Imy current forecast is for the La Niña to be stronger than last years La Niña, with a peak of -1.6 or so. Yes, right now the models are forecasting for the La Niña to stay at around -.8, but the recent data indicates that the subsurface is currently colder in the enso region than last year at this time, and last year peaked at -1.3. 

[Go Kart Mozart]

Nice to see some blue 850s show up on the last few euro runs.  It's coming!

 

[512high]

2 hours ago, Go Kart Mozart said:

Nice to see some blue 850s show up on the last few euro runs.  It's coming!

 

 

2 hours ago, Go Kart Mozart said:

Nice to see some blue 850s show up on the last few euro runs.  It's coming!

 

PLEASE! I'm tired of the swamp ass dews.............

[ORH_wxman]

There's been extremely rapid cooling in the subsurface in the last 3 weeks...definitely starting to look like La Nina as we head into the fall.

 

 

[40/70 Benchmark]

On 7/29/2021 at 7:59 PM, raindancewx said:

My interest in looking at the NAO is mostly from a national temperature perspective rather than identifying periods for Nor'easters or something. In that sense, it is most useful from about mid-January to mid-April. For Nov-Jan, the AO is more important in terms of long-term correlations.  For precipitation, the NAO actually has some pretty strong correlations in various places too. The WPO is actually pretty useful in Sept-Nov, and then in Feb-Apr for temperature patterns too, in a correlation sense. Locally, the +NAO/AO is actually a good signal later on if it happens in November from what I can see.

The seven winters with 'rising' but still low solar are all -AO winters too, if that's your preferred measure. November NAO values are a good long-term indicator here for how wet late Spring will be, but otherwise it's not that useful until later in winter for national patterns for temps/precip. The long-term WPO correlations on the other hand correspond almost perfectly to some of the wild temperature pattern swings in the Fall and Spring in the past year.

My point with the NAO/AO stuff isn't that I can see with 100% certainty that they'll be negative this winter. It's just we're nearing the end of the historical 'solar' time frame when odds of a -NAO winter are likely. To me it's worth figuring out whether we'll have one more winter with an extended -NAO/AO before we predominantly switch back to mostly positive NAO/AO winters. New Mexico is uniquely weird in that we get our top snow years in both the highest NAO/AO and lowest NAO/AO winters. So I'm actually pretty indifferent about what ends up happening typically, since most years are relatively neutral. 

You could see solar activity rise from 16 sunspots/month to 30, about the level of gain from 2019-20 to 2020-21. Or you could see it rise to 68 or something if we're going into a bigger cycle (more active sun) than last time. In the latter case, there is no particular signal in the solar data. April 2021 NAO was also negative like April 2020, which hadn't happened in forever prior to 2020, so that was my first tip off to pay attention to it again this year.

Most people seem to use Nino 3.4 as an estimate for what the PNA is going to do, even though the correlation is ~0.3 r-squared for DJF, and much weaker in December. The Nino 3.4 to PNA correlation in August is literally stronger than December to Nino 3.4 for the PNA, so I always find the way it is used to be a bit strange. The image below actually supports a La Nina though, as the PNA correlation to Nino 3.4 is negative (+PNA = -ENSO) long term.

https://psl.noaa.gov/data/correlation/table/corr.table_dec.txt

https://psl.noaa.gov/data/correlation/table/corr.table_jan.txt

https://psl.noaa.gov/data/correlation/table/corr.table_feb.txt

I get that the solar cycle has some value, as everything should be considered, but it is not the only factor. The fact of the matter is that in the grand scheme of things, we have been in quite a stretch of predominately +NAO seasons. Prior to last winter, we had experienced just one negative NAO DM month dating back to March 2013 (March 2018). Again, I understand that neg NAO is more favored around and immediately following solar min, but other than that context, we are most assuredly not due for positive NAO winter seasons.

Quite the contrary. I'm not suggesting that this means that we have to see a succession of negative NAO seasons, but it is what it is.

[40/70 Benchmark]

On 7/29/2021 at 10:27 PM, George001 said:

I have been looking into it a bit more and not only is the temperatures in the enso region (both surface and subsurface) starting to decrease, but tropical storm activity and the SOI is increasing. Both of these things indicate that the atmospheric pattern reflects La Niña. The Enso 3.4 region being down to -.5 degrees below average already in late July would put us on track to follow the coldest members of the cfs v2 enso forecast ensembles. The mean right now for that model is roughly -.8 in the enso 3.4 region, however by now the mean had us at roughly -.3 in the enso 3.4 region and we are at -.5. Many of the ensembles in the cfs v2 model that have us at -.5 by now take us to a moderate La Niña. With how the atmosphere and subsurface look combined with the trend of the models with each update increasing the strength of the La Niña forecasted for winter, I would not be surprised if the La Niña is already at moderate strength by September, potentially increasing even more and becoming stronger than last years La Niña. I know I said I was thinking -.8 to -.9 was likely before but looking at the latest data I’m starting to believe we could see a peak of -1.2 to -1.6 in the fall. 

This la nina is not going to be strong. I wouldn't rule out nudging into moderate territory, but weak la nina is by far the most favored outcome and has been for a bit.

[40/70 Benchmark]

4 hours ago, ORH_wxman said:

There's been extremely rapid cooling in the subsurface in the last 3 weeks...definitely starting to look like La Nina as we head into the fall.

 

 

Yea, been hedging that way for a while, but it feels like some folks get too carried away with the subsurface....those intense anomalies often don't entirely make it to the surface. Def. a feather in the hat of the la nina camp, though.

[ORH_wxman]

1 hour ago, 40/70 Benchmark said:

Yea, been hedging that way for a while, but it feels like some folks get too carried away with the subsurface....those intense anomalies often don't entirely make it to the surface. Def. a feather in the hat of the la nina camp, though.

We'll know a lot more in another month or so. But I do think it's becoming much less likely we stay neutral. It will be hard to get anything stronger than moderate though, I agree on that point. It's starting pretty late. I'd definitely say weak La Nina is still the most likely but moderate is becoming a realistic option.

[40/70 Benchmark]

32 minutes ago, ORH_wxman said:

We'll know a lot more in another month or so. But I do think it's becoming much less likely we stay neutral. It will be hard to get anything stronger than moderate though, I agree on that point. It's starting pretty late. I'd definitely say weak La Nina is still the most likely but moderate is becoming a realistic option.

I honestly don't think it matters much. The MEI is pretty robust, so I'd be considering moderate analogs, anyway.

[George001]

3 hours ago, 40/70 Benchmark said:

I honestly don't think it matters much. The MEI is pretty robust, so I'd be considering moderate analogs, anyway.

A month ago I was looking at last year and 2017-2018 as my main analogs but viewing the most recent mei data Im starting to like 2010-2011 as a possible analog (it’s still very early so this is subject to change). 1995-1996 while I’d really like to see it, the Pacific Ocean right now is too warm and the western pacific blob is too far west for me to be on board with a pacific that favorable during the winter. What are your early thoughts? I was thinking since the MEI is already -1.5 even if by oni we don’t quite get to strong La Niña, that the atmospheric pattern will reflect strong La Niña. I’m looking forward to reading your winter forecast this year and comparing our ideas. When I post my winter forecast I welcome feedback from you guys who are more experienced. 

[raindancewx]

One very simple rule for SSTs is that from 1950-2020, you've never had Nino 3.4 drop by more than 1C from September to December-February. We're at 26.7C on the weeklies week one of August. A moderate La Nina would be 25.5C or colder in winter. Will August finish at 26.5C or colder? Possibly. Will September be below 26.5C - I would say so. But keep in mind, even though a 1C drop has been observed from September to winter, most cooling trends from September to Dec-Feb end up far weaker than that in practice. Last September was 25.88C, and the winter was 25.58C.

If you use last year as an example, the big spikes up/down in the subsurface tend to lead the surface peaks by 3-6 weeks. So the big drop off now, once it stops, indicates we might see another ENSO peak prior to 11/1. Against the long-term averages, Nino 3.4 was coldest in November 2020 (25.3C v. 26.5C long-term average) after the subsurface was coldest in October.

 

[40/70 Benchmark]

14 hours ago, George001 said:

A month ago I was looking at last year and 2017-2018 as my main analogs but viewing the most recent mei data Im starting to like 2010-2011 as a possible analog (it’s still very early so this is subject to change). 1995-1996 while I’d really like to see it, the Pacific Ocean right now is too warm and the western pacific blob is too far west for me to be on board with a pacific that favorable during the winter. What are your early thoughts? I was thinking since the MEI is already -1.5 even if by oni we don’t quite get to strong La Niña, that the atmospheric pattern will reflect strong La Niña. I’m looking forward to reading your winter forecast this year and comparing our ideas. When I post my winter forecast I welcome feedback from you guys who are more experienced. 

Be careful with that linear line of thinking....like I was saying to Will above....the MEI is a measure of how well coupled the ocean (ENSO event) is with the atmosphere, rather than a strict measure of strength. So while I do modify my list of analogs somewhat based upon MEI data, it should not be substituted for the ONI. A weak la nina with a strong MEI means that we have a weak la nina that is very well coupled with the atmosphere, not a strong la nina. What this means is that this particular ENSO event is more likely to be able to play a prominent role in modulating the forcing relative to other events of comparable ONI strength that are less coupled with the atmosphere....IE we are more likely to see a la nina footprint over the course of a season than others. I would also venture to say that the prudent course of action is to err more towards moderate ONI analogs, then cool-neutral, since we know it is impacting the atmosphere somewhat more proficiently than other events of comparable ONI.

ONI=strength of influence, MEI=the ability of the ENSO event to impart its will around the hemisphere, regardless of strength.

A crude sports analogy is to think of the fact that your most powerful athletes are not always the most prolific..., sure, there is a correlation. But the best athletes a feature the nexus of strength and skill.

[ORH_wxman]

I was starting to dive into the analogs a little more closely for La Ninas with a -AO and I still can't believe last year. This screams El Nino even though it was a moderate La Nina.

[SJonesWX]

24 minutes ago, ORH_wxman said:

I was starting to dive into the analogs a little more closely for La Ninas with a -AO and I still can't believe last year. This screams El Nino even though it was a moderate La Nina.

too soon. The wounds have not completely healed yet.

[raindancewx]

There were a lot of signs last Fall that the pattern was going to be pretty special at times. 2007-08 never matched up super well for timing in the winter, but you did have a massive cold dump into the US from 1/16-2/15 that doesn't really show up if you just look at Jan/Feb individually. Main difference without looking is the ridging in the SE pushed it somewhat further West than in February 2021. I was annoyed at the severity of the cold, I thought I was pretty bullish with half the US 5-10 degrees below average for two weeks using the 2007-08 analog as the basis for late winter cold.

We went though this last year too - but the cold ENSOs after two El Ninos all tend to feature several incredible cold snaps nationally in winter and spring. Last year was no exception. You have amazingly potent cold snaps in 1931-32, 1959-60, 1970-71, 1978-79, 1988-89, even 2016-17 if you know when to look by timing.

 

[George001]

In the winter of 2010-2011, the consensus by most forecasters was that winter was going to be awful due to the strong La Niña in place. Sometimes La Niña doesn’t couple with the atmosphere so it ends up not being a major driver of the weather pattern, but in 2010-2011 that was not the case. The 2010-2011 La Niña was strong no matter how you look at, ONI, MEI, subsurface, SOI every indicator you looked at reflected strong La Niña conditions. Going back and reading several winter forecasts, the consensus was that strong La Niña was not only in place but would be the dominant pattern driver, so winter would suck. That is one of several reasons the 2010-2011 winter is really fascinating for me, it was not only the winter that sparked my passion for severe blizzards, but it was supposed to suck and ended up being one of the snowiest winters on record in my area. I ask myself, how did this happen? If you look at the SST configuration in December 2010, you have an extremely strong west based La Niña, but even outside the Enso region temps were well below average in the entire eastern Pacific Ocean. On top of that you had warm waters slightly west of Greenland, which is an sst configuration that favors severe North Atlantic blocking, with the polar jet being forced to the south into the United States rather than locked up in the North Pole. While most forecasters missed this, there were a couple who did forecast a big winter despite the narrative that strong La Niña= ratter. Isotherm I know went big that year and discussed how the severe North Atlantic blocking as well as strong la nina would be the dominant pattern drivers, which would bring a big winter to areas farther north like New England a big winter, since while the storm track would be more north due to La Niña, you had severe North Atlantic blocking causing these lows to redevelop and come up the east coast rather than just cutting into Wisconsin and bringing us a rainstorm. However he did not go big farther south like DC due to the La Niña. This idea ended up being correct. If you compare that with the current sst pattern, the La Niña is much weaker, and the Pacific Ocean is warmer. However, there is that big area of warmer waters near Greenland. That was there last year as well, not quite as pronounced as 2010-2011 but still there. Last year we did get severe North Atlantic blocking at times, but the pacific jet was so strong that even with the blocking we would get several storms with a perfect track and just a cold rain with all that warm pacific air flooding the country. The SST configuration is even more favorable for North Atlantic blocking than it was last year, it looks more like 2010-2011 in that region. The pacific is more mixed, not on fire like last year but not well below average like 2010-2011 either. Things are looking really good right now for an above average winter.

[raindancewx]

I was curious to see if the enhancement area you get from subtracting the "top -NAO winters" from the "top +NAO winters" for 1950-51 to 2020-21 resembled the snow pattern last year. The most enhancement is for the deep south to be sure. But the cold push was severe enough last year that the biggest enhancement was in places that see very little snow. You can interpret this as "Chicago averages 46% more snow in the top -NAO winters since 1950 compared to the top +NAO winters since 1950".

Pretty sure the light blue area extends into northern Michigan, SE Canada, and northern New England, but I didn't really look. The deep blue area likely goes deeper into the South, but those places often average under five inches of snow or see snow in less than 70% of years, so the data gets weird real fast. My guess is if we have another winter with blocking, the snow would more closely resemble my map than the 2020-21 snow observations.

Not a huge fan of the NAO as a temperature indicator for most of the US overall but it does favor snowy conditions in most spots nationally when negative. That's the main reason I look at it.

My map is comparing total July-June snow in the years that had -NAO v. +NAO winters, i.e. not just the snow that fell in winter. Both sets of years include a number of warm and cool ENSO events, so shouldn't be a huge factor.

[snowman19]

https://climateimpactcompany.com/daily-feature-la-nina-modoki-risk-later-this-year-2/

[40/70 Benchmark]

On 8/20/2021 at 7:15 AM, snowman19 said:

https://climateimpactcompany.com/daily-feature-la-nina-modoki-risk-later-this-year-2/

Modoki la nina is not preferred for east coast weather fans....its the opposite of el nino, whereas modoki el nino is favorable. However,  modoki la nina doesn't seem quite as hostile as east-based el nino because the forcing is usually weaker. The moral of the story is that you always want the coolest anomalies in the eastern based regions because it tends to focus convection further west, all things being equal.