2019 ENSO

[raindancewx]

I don't do Fall outlooks, but if I had done a Fall outlook, you really can't find a better match long-term than 1995 for the Nino zones. But I do expect 2007 to take over later in the fall.

This is Nino 3.4

1995  27.57  27.49  27.75  28.10  27.82  27.59  27.08  26.23

2007  27.24  26.88  27.10  27.50  27.46  27.37  26.71  26.14

2020  27.14  27.11  27.76  28.17  27.65  27.38  26.99  26.30

Nino 4 -

1995  29.04  28.91  29.03  29.14  29.31  29.18  28.93  28.65 

2007  28.97  28.66  28.66  28.73  28.84  28.90  28.68  28.48

2020  29.16  28.97  29.07  29.15  29.00  29.09  28.89  28.50

The biggest problem with 1995 is the PDO I think -

2020-03-01T00:00:00Z	-0.82
2020-04-01T00:00:00Z	-0.57
2020-05-01T00:00:00Z	0.09
2020-06-01T00:00:00Z	-0.08
2020-07-01T00:00:00Z	-0.38
2020-08-01T00:00:00Z	-0.28

https://oceanview.pfeg.noaa.gov/erddap/tabledap/cciea_OC_PDO.htmlTable?time,PDO

1995-03-01T00:00:00Z	0.75
1995-04-01T00:00:00Z	0.83
1995-05-01T00:00:00Z	1.46
1995-06-01T00:00:00Z	1.27
1995-07-01T00:00:00Z	1.71
1995-08-01T00:00:00Z	0.21

90% of the time, maybe more, the PDO values are -2 to +2. So +1.7 in July 1995 and -0.4 in July 2020 is a massive difference. Even the August difference is still pretty substantial. It popped back up too - to +1.2 in September, and on/off again was pretty positive through Spring. Nino 1.2 has been warming. If that continues into October, then the PDO won't go as negative as it looked a few weeks ago. If it really warmed up a lot, it might even go positive, but I don't expect that. You can see cooling lately in some of the areas you'd want for a -PDO on Tropical Tidbits (by the coast of Western Canada), but also hints of cooling east of Japan where you'd want cooling for the +PDO.

This is what I have tentatively for winter, with the analogs removed, since people need to come up with their own ideas -

Here is how the analog package looks compared to September. It is also similar on solar, ENSO trends, and actual US temperatures for July-September (assuming the forecast NE/Western heat continues to  burn off cold in those areas). You can see that the transition in the La Nina is the same in my analogs as on the CFS. I was a bit surprised to see the cold eastern Atlantic show up in September in both 2020 and the analogs, because it definitely warms up by winter.

 

[raindancewx]

Nino 4 looks like it is cooling at the surface, but still pretty warm below. It does look like the cold is bleeding West, which is what the models show, and what happened in years like 2007.

[raindancewx]

Still looks a lot like 2007, especially in Nino 3.4 and 4.

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 05SEP2007     19.4-1.1     23.7-1.2     26.0-0.8     28.3-0.4
 12SEP2007     18.6-1.8     23.6-1.3     25.8-1.0     28.0-0.6
 19SEP2007     18.5-2.0     23.6-1.2     25.8-0.9     28.0-0.7
 26SEP2007     18.4-2.1     23.2-1.7     25.6-1.1     28.0-0.7

 02SEP2020     18.9-1.6     23.6-1.3     25.8-0.9     28.4-0.3
 09SEP2020     19.5-1.0     23.4-1.4     25.7-1.0     28.5-0.2
 16SEP2020     20.0-0.4     23.6-1.3     25.9-0.8     28.2-0.4
 23SEP2020     19.6-0.8     23.6-1.2     25.7-1.0     28.1-0.5

October is depicted like a relatively canonical MJO phase five October, and an almost identical match to 1964 on the CFS

[andyhb]

Further intensification and westward progression of the Niña seems likely should this trade surge on the ECMWF come to fruition. Looks to me like we’re heading for a moderate event. Seems like MEI is paralleling 2007 as well to a decent degree.

[It's Always Sunny]

7 hours ago, andyhb said:

Further intensification and westward progression of the Niña seems likely should this trade surge on the ECMWF come to fruition. Looks to me like we’re heading for a moderate event. Seems like MEI is paralleling 2007 as well to a decent degree.

I agree. CFS showing it to a lesser degree:

[andyhb]

Can see it picking up the low frequency signal there.

[raindancewx]

Canadian has a long lasting La Nina that gradually becomes centered pretty far West. It trended stronger than before. Nino 4 would stay cold for a long time in this depiction - that hasn't happened in close to a decade.

The monthly sea surface temperature readings for the September monthlies should look a lot like 2007.

On the Canadian, the cold ring by NW North America tries to develop around the warm tongue east of Japan. That'd be a pretty healthy and canonical -PDO, which is a pretty warm signal for the SE. Good for the NW to be cold. Pretty strong dry signal in the SW, especially Fall and Spring, locally it peaks as an indicator in November and May.

[raindancewx]

On 9/22/2020 at 9:58 AM, 40/70 Benchmark said:

@raindancewx What are your thoughts on this research? +QBO in cool ENSO seasons favoring more N PAC ridging....

There seem to be two areas impacted by the QBO in the US from what I can see. For whatever reason, there is a pretty big difference in the South Central US between La Ninas with a QBO -2 or lower and La Ninas with a QBO +2 or higher.  The same NW areas are still cold though.

The years with a drop off in QBO values in Summer (JJA) to Winter (DJF) seem to feature at least some cold dumps into the central US more reliably. So that's the coldest La Nina/QBO composite I could find. The rising QBO years are more amplified, with broader warmth and cold in the NW. We aren't in the first situation. The QBO was about 0 in JJA and rising. That map (rising) as a composite gives the same features as winters with a QBO >2. So unless you live in Kansas, most areas are pretty similar regardless of what you do with the QBO. These composites are so small and erratic, that I'd say they mean almost nothing in aggregate. I did draw in some dummy high/low positions without checking the maps as a guess for how the composites might be varying.

I'm personally much more interested in the ACE value for the Atlantic at this point. The long-term average is about 105.6 so we're still technically below an average season (1981-2010), and La Ninas average 128 ACE from 1930-2019. October averages about 15 ACE, and I doubt there has ever been an October ACE over 50.

Locally, there is a very strong correlation in La Nina years to how cold we get at the coldest time of the year here - Dec 16-Jan 15, when the average high is 46 and the average low is 24. So quite curious to see how high the ACE gets. The projected mid-Dec to mid-Jan value high on the image below is reliably (~5/6) within 3.3 degrees of observations, and actually tends to be a lot closer than that if ACE isn't under 65 or so where most of the outliers are. I've looked at Neutral and El Nino years here, and you don't have a relationship like this in any month from October-May. The relationship holds well over time too - 1933 is the dot furthest to the right with the highest ACE. My sense is a low ACE La Nina went into phases 4-5-6 fairly often during the heat of the hurricane season. Five, or the "five look" with a warm Nino 4 can be very cold here if it shows up again in late December like in 2007.

Below the surface, 100-180W looks a lot like a combination of 2003, 2007, 2010, 2017 for July-September, and the match is fairly close to what the models show for October and how September ended up. I'm not a fan of 2010 and 2017, they both have timing and severity issues. There are non-ENSO things I like about 2003, but can go more into that when I put my outlook up in a week or two.

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

[raindancewx]

All of the Nino zones came in below the 1951-2010 historical averages in September. Compared to September 2007, the current La Nina is consistently 0.2-0.4C warmer in all zones

                  Nino 4     Nino 3.4    Nino 3     Nino 1.2

2007         28.11         25.61       23.63          19.75

2020         28.28         25.96       23.93          19.54

In the 1950-2019 data, you don't have any years where Nino 3.4 dropped off by more than ~1.0C from September to Dec-Feb. So it's pretty likely this event will come in 25.0C or warmer, as the subsurface data had previously implied. I think a couple months could come in around 25.5C - but we'll have to see.

[andyhb]

Latest Niño 3.4 multi-model ensemble from BOM is pretty locked into a moderate or even strong Niña peak in December.

[It's Always Sunny]

32 minutes ago, andyhb said:

Latest Niño 3.4 multi-model ensemble from BOM is pretty locked into a moderate or even strong Niña peak in December.

Yeah I was looking at that yesterday it's definitely not out of the realm of possibility. Do you know what may be causing the NOAA/NASA/BoM models to go stronger? Wasn't sure if it was a model bias of some sort. One thought of mine is that those models in particular have a stronger area of suppression over the central Pacific resulting in stronger easterlies?

[andyhb]

10 hours ago, It's Always Sunny said:

Yeah I was looking at that yesterday it's definitely not out of the realm of possibility. Do you know what may be causing the NOAA/NASA/BoM models to go stronger? Wasn't sure if it was a model bias of some sort. One thought of mine is that those models in particular have a stronger area of suppression over the central Pacific resulting in stronger easterlies?

Your guess is as good as mine. I know the Euro tends to be a bit warm biased with ENSO and the CFS (NOAA) tends to be bullish with ENSO so I’d stake my claims somewhere in between. We haven’t had a Niña this well developed since probably 2010-2012.

[It's Always Sunny]

6 minutes ago, andyhb said:

Your guess is as good as mine. I know the Euro tends to be a bit warm biased with ENSO and the CFS (NOAA) tends to be bullish with ENSO so I’d stake my claims somewhere in between. We haven’t had a Niña this well developed since probably 2010-2012.

Yeah that would make sense. I'm really interested in how this upcoming severe season will play out since 2010 & 2011 were bonkers with a well established (moderate to strong) La Nina. I read your post about the drought and its downstream affect on early season severe potential in the east. Good stuff.

[CheeselandSkies]

1 hour ago, It's Always Sunny said:

Yeah that would make sense. I'm really interested in how this upcoming severe season will play out since 2010 & 2011 were bonkers with a well established (moderate to strong) La Nina. I read your post about the drought and its downstream affect on early season severe potential in the east. Good stuff.

2010 was decent across the board (May 10/19 in OK, May 22 in SD, several days in June along/east of the MS). 2011 was definitely very east-weighted not to mention bonkers in April. 2012 was drought city from the Rockies to the Appalachians and from the Rio Grande to the Red of the North; but still had two very high-end events early.

[raindancewx]

General warming again in Nino 1.2 Way ahead of 2016 and 2017, 2008 at this point. Somewhat colder than 2011 too most spots.

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 02SEP2020     18.9-1.6     23.6-1.3     25.8-0.9     28.4-0.3
 09SEP2020     19.5-1.0     23.4-1.4     25.7-1.0     28.5-0.2
 16SEP2020     20.0-0.4     23.6-1.3     25.9-0.8     28.2-0.4
 23SEP2020     19.6-0.8     23.6-1.2     25.7-1.0     28.1-0.5
 30SEP2020     20.1-0.5     23.8-1.1     25.6-1.1     27.9-0.7

 30AUG2017     20.3-0.2     24.5-0.4     26.5-0.2     28.8 0.2
 06SEP2017     20.4-0.1     24.3-0.6     26.2-0.6     28.7 0.1
 13SEP2017     19.7-0.7     24.0-0.9     26.1-0.6     28.7 0.0
 20SEP2017     19.3-1.1     23.9-1.0     26.3-0.4     28.7 0.0
 27SEP2017     19.5-1.0     24.4-0.5     26.5-0.2     28.4-0.2

 31AUG2016     20.9 0.3     24.6-0.3     26.0-0.7     28.5-0.1
 07SEP2016     20.8 0.3     24.6-0.3     26.1-0.7     28.6-0.1
 14SEP2016     20.6 0.2     24.7-0.2     26.1-0.6     28.5-0.2
 21SEP2016     21.2 0.8     24.8-0.1     26.3-0.4     28.5-0.2
 28SEP2016     21.2 0.6     24.7-0.2     25.9-0.8     28.1-0.5

 31AUG2011     20.0-0.5     24.4-0.5     26.1-0.7     28.3-0.4
 07SEP2011     19.7-0.7     24.2-0.7     26.1-0.7     28.2-0.5
 14SEP2011     19.6-0.8     24.1-0.7     26.0-0.8     28.0-0.7
 21SEP2011     19.8-0.6     24.3-0.6     25.9-0.9     27.8-0.9
 28SEP2011     19.9-0.6     24.1-0.7     26.0-0.7     28.0-0.7

 03SEP2008     21.3 0.8     25.3 0.4     26.6-0.2     28.1-0.6
 10SEP2008     21.0 0.6     25.2 0.3     26.6-0.2     28.1-0.6
 17SEP2008     21.1 0.8     24.9 0.1     26.4-0.4     28.1-0.6
 24SEP2008     21.3 0.8     25.1 0.2     26.4-0.4     28.1-0.6
 01OCT2008     21.0 0.4     24.7-0.2     26.2-0.5     28.3-0.4

Still way warmer than 2010 though in all zones.

 01SEP2010     18.8-1.7     23.4-1.5     25.1-1.7     27.2-1.5
 08SEP2010     19.1-1.3     23.5-1.4     25.2-1.6     27.1-1.6
 15SEP2010     18.6-1.8     23.4-1.5     25.1-1.6     27.1-1.6
 22SEP2010     19.3-1.2     24.0-0.8     25.1-1.6     27.1-1.6
 29SEP2010     19.2-1.4     23.5-1.3     24.8-1.9     27.1-1.6
 06OCT2010     18.7-1.9     23.2-1.7     24.8-1.9     27.1-1.6

Very close to 2007 in Nino 3.4 and identical in 4. Pretty different in Nino 1.2 - but 2007 warmed up a lot there in December, so might snap back toward 2007 then. 1995 is close too.

 05SEP2007     19.4-1.1     23.7-1.2     26.0-0.8     28.3-0.4
 12SEP2007     18.6-1.8     23.6-1.3     25.8-1.0     28.0-0.6
 19SEP2007     18.5-2.0     23.6-1.2     25.8-0.9     28.0-0.7
 26SEP2007     18.4-2.1     23.2-1.7     25.6-1.1     28.0-0.7
 03OCT2007     18.3-2.3     23.2-1.7     25.4-1.3     27.9-0.7

 06SEP1995     20.4 0.0     24.1-0.8     26.0-0.8     28.2-0.5
 13SEP1995     19.9-0.5     24.1-0.8     26.0-0.7     28.0-0.6
 20SEP1995     20.2-0.2     24.0-0.9     26.1-0.7     28.4-0.3
 27SEP1995     20.2-0.3     23.9-1.0     25.9-0.8     28.4-0.3

 30SEP2020     20.1-0.5     23.8-1.1     25.6-1.1     27.9-0.7

The September NAO was more positive than I expected. When I run my NAO script, it suggested several possible blends, but I think this one is probably the best for what it will do:

2020: 1961, 2003, 2007. March would also be somewhat negative in this scenario.

In prior years, 1993, 2017, 2017 was a good blend for 2019. Generally, you look for the best match that has similar ENSO tendencies for May-Apr and Sept-Mar for the NAO state. If you don't have a good ENSO match available because of some unusual combination of NAO changes, the best blend overall will typically work, based on testing from 1995-2019.

1975 is a good match to 2018

1990, 1990, 1994 was a good match for 2017

 2004, 2010, 2011 was a good match for 2016

1992, 1994 was a good match for 2015.

[raindancewx]

As best I can tell, there are only 17 hurricanes to hit the US Gulf Coast in October since 1931. It's interesting to see 1964 show up as one of the years (Hilda), with one of the once a decade non-Florida hurricane landfalls on the Gulf in October. Have to see if Delta actually follows the current projected track.

The closest tracks since 1931 in October to Delta are probably Nate (2017), Hilda (1964), Opal (1995), Lili (2002), and Jerry (1989). Of those years, 1964 is the only one with a warm NW October though (currently 5-10 above normal in some places in Oregon).

[40/70 Benchmark]

On 10/5/2020 at 2:21 AM, It's Always Sunny said:

Yeah I was looking at that yesterday it's definitely not out of the realm of possibility. Do you know what may be causing the NOAA/NASA/BoM models to go stronger? Wasn't sure if it was a model bias of some sort. One thought of mine is that those models in particular have a stronger area of suppression over the central Pacific resulting in stronger easterlies?

I would be modestly surprised if this la nina registered as an official moderate event per ONI, and would be stunned if it ended up strong...I guess we will see.

[40/70 Benchmark]

It will be interesting to see how much DELTA going coo coo for coco puffs can spike the ACE. Should remain a major for several days.

[It's Always Sunny]

22 hours ago, CheeselandSkies said:

2010 was decent across the board (May 10/19 in OK, May 22 in SD, several days in June along/east of the MS). 2011 was definitely very east-weighted not to mention bonkers in April. 2012 was drought city from the Rockies to the Appalachians and from the Rio Grande to the Red of the North; but still had two very high-end events early.

I was just referring to how active they were. 2010 had record setting May (304)  & June (324) numbers. 2011 had a whopping 758 tornados in April (highest ever on record) and May had 326 which was also amongst the highest. You're right about 2012 relatively speaking.

[andyhb]

Those are definitely not record setting May numbers. May 2003, 2004, and 2008 all had around 500 tornadoes, 2015 and 2019 were also more active.

[It's Always Sunny]

19 minutes ago, andyhb said:

Those are definitely not record setting May numbers. May 2003, 2004, and 2008 all had around 500 tornadoes, 2015 and 2019 were also more active.

What I meant by record setting is top 10-15  I should've phrased that differently. 2003 had 543, 2004 had 509, 2008 had 462. May 2011 would be 9th most active May. May 2010 is actually 12th but still impressive in my opinion.

[raindancewx]

ACE on the CSU site has updated at least twice today and is currently 111.4 as of late Tuesday.

It seems generally you add 1 point for a weak tropical storm that lasts all day, 2 for a weak hurricane that lasts all day, 3 for a major hurricane, and 4 for a category 5. This system has four days left until it dies, so the ACE should get into the low 120s, which is still the mid point of the 80-160 La Nina composite favoring a cold NW. By 10/10, the season is typically 85% or more over, but it can be less, and it can be more. I lean toward a couple more tropical storms after Delta, but this is probably the last big system this year. You'll probably see some big weakening if Delta hit Mexico, and then a larger, weaker hurricane after. The Gulf of Mexico is pretty spent at the moment, so it is fairly cold. So I lean toward 2.5 points a day for the next four days from Delta. We'll see how close 10/10, at 5 pm MST is to 121 ACE.

I'm planning to release my outlook 10/10. I've got 50+ slides this year, but most of it is pictures. I've got a pretty hot winter in some parts of the South - mostly the coastal SE and especially Texas. I have the interior West cold, but not that cold. I have most of the East warm, but still much colder than last year. 

Statistically, the odds of a wet December here are near 0% if the ACE is above 160, and near 50% if the ACE is under 160 in La Ninas over the past 90 years. So do want to see how high the ACE gets. Since mid-September my outlook has assumed years with 95-175 Atlantic ACE would be similar, given about 135 ACE this year.

[raindancewx]

This is the Euro plume from October 1 for the La Nina. I've drawn in my expectations - I think this event could peak pretty strong. But I also think the Euro is right about a pretty quick turnaround/warm up after January.

[StormchaserChuck!]

The Nina will die muahaha

[raindancewx]

Cold ENSO with low sea ice since 2007...v. Cold ENSO with (relatively) high sea ice since 2007. Really curious to see if this works in 2020. I don't really look at 2007, 2012, and 2016 as similar...they are very different ENSO events. But they all have the low-sea ice and cold West. I put 2011 in both because it was cold in NM/TX at the border of the two cold areas, and the 4.3m square km also seems to be the borderline threshold for this. The ACE index is higher on the left image, so maybe this is just all an Atlantic thing, since both sea ice and ACE are tied broadly to the AMO.

[StormchaserChuck!]

What do you think about Western drought and Washington drought compared to this year?

[Eric11]

16 hours ago, raindancewx said:

This is the Euro plume from October 1 for the La Nina. I've drawn in my expectations - I think this event could peak pretty strong. But I also think the Euro is right about a pretty quick turnaround/warm up after January.

Hey raindancewx,I'm a newbie interested in atomspheric science and have been tracking your post since last summer.I lived in China so I'm more familiar with the climate in East Asia than America.One thing I'd like to share is that I found 2020 really behaves like 1954,at least in East Asia part.Both have rather weak monsoon,record-breaking,prolonged flood, and definitely late starting of typhoon season.Outside Asia,some other similarities can be found in America like the western drought/big ridge in summertime(I'm not quite clear what's 1954 autumn looks like),a active hurricane season but with moderate ACE(1954 had 16 storms with 110 ACE,2020 has 24 storms with around 111 ACE so far).1954 and 2020 are both low solar years, fast-transition Nina after prolonged,weak Nino events.So why not consider 1954 as a good analog?I know the subsurface temperature differs too much but I rather prefer a weaker,shorter 1954-like event for this year.Btw,2007 really works out as a good analog in East Asia,appreciate for your precise prediction!

[andyhb]

That is quite a strong signal from the ECMWF seasonal, which is commonly warm biased with ENSO.

[raindancewx]

7 hours ago, Eric11 said:

Hey raindancewx,I'm a newbie interested in atomspheric science and have been tracking your post since last summer.I lived in China so I'm more familiar with the climate in East Asia than America.One thing I'd like to share is that I found 2020 really behaves like 1954,at least in East Asia part.Both have rather weak monsoon,record-breaking,prolonged flood, and definitely late starting of typhoon season.Outside Asia,some other similarities can be found in America like the western drought/big ridge in summertime(I'm not quite clear what's 1954 autumn looks like),a active hurricane season but with moderate ACE(1954 had 16 storms with 110 ACE,2020 has 24 storms with around 111 ACE so far).1954 and 2020 are both low solar years, fast-transition Nina after prolonged,weak Nino events.So why not consider 1954 as a good analog?I know the subsurface temperature differs too much but I rather prefer a weaker,shorter 1954-like event for this year.Btw,2007 really works out as a good analog in East Asia,appreciate for your precise prediction!

I like 1954 as an analog. My statistical predictors for temperatures in the Southwest have that year as the best match to 2020 - huge number of hot Summer days, similar ENSO, ENSO trends, and solar, weak monsoon in the US, India and East Asia. For La Nina years the more recent events tend to be surrounded by warm waters in the Pacific that were not really present in older years like 1954. I view La Nina winters in the US as more Atlantic driven than Pacific driven in most spots, so the mid-1950s to 1963 representing the late warm AMO of that era is similar too, Where I live, the top matches for June-September in a La Nina are 2007, 1973, and 1954. My guess is the similarities to 1954 and 2020 have to do with relatively early substantial La Nina strength late Summer in both years and similar MJO trends and similar net ACE output in the Atlantic. But the MJO data doesn't exist before the 1970s. The sea ice extent in some years in the 1950s probably dropped to around 5 million square kilometers in September, but that is still well above this year too, which has to have some effect. 

Where I live, the coldest La Nina years tend to follow a) early heat (first 90 degree Fahrenheit (F) years), b) consistent heat - I know 1954 had 118 days 87F or hotter from April-October. We're at 111 this year. Both had 90 degree heat by mid-May

If I did a purely ENSO based winter forecast, I'd probably blend 1954, 1964, 2007 for the winter, double weighting 1954 and 2007. For an American perspective, one of the things I like about 1954 is it is a La Nina with an El Nino after a very warm El Nino winter as 2020 will be. Something like this is probably the best case scenario for the West. It seems to be favored look in low-sea ice cold ENSO since 2007, in cold-ENSO after El Nino (1931, 1954, 1988, 2007, 2016), and in strong La Ninas (2007, 1988, 1954).

[raindancewx]

Here it is: My 2020-21 Winter Outlook for anyone who cares.

https://www.scribd.com/document/479516526/Winter-2020-21-Outlook

My winter look is ultimately not that different from:

a) Cold-ENSO years following two El Nino winters. Since 1930, these are 1931, 1959, 1970, 1978, 2016 as a blend. The 1942 and 2005 La Ninas don't "look" like the others, but I think it is because they followed THREE El Ninos, and not two.

b) Cold ENSO years since 2007 with very low-sea ice. The cut off seems to be <4.3 million square km sea-ice extent in September.

c) Strong La Ninas. The strongest La Ninas (<25.0C Nino 3.4 DJF) are 1973, 1975, 1988, 1999, 2007. The blend of those years is similar to A & B. Don't know that we get that strong, but it doesn't really impact directly. The crappier strong La Ninas still follow the other patterns - 1999 is the hottest and highest ACE for instance. The years after El Ninos are generally better in the West, and so on, whereas 1975/1999 followed La Ninas.

d) +NAO La Nina winter composite. I find if a winter follows an El Nino winter, you want the NAO to be positive in October for a -NAO winter. If you have a -NAO October, you tend to get a +NAO winter. That said, I think you'll see the NAO go negative for at least a time in December and March.

e) Middling ACE years. The middle ACE years in La Ninas tend to be colder in the West, hotter in the East.