2019 ENSO

[40/70 Benchmark]

Just now, 40/70 Benchmark said:

SO MEI value held at -1-2

https://psl.noaa.gov/enso/mei/

 

[raindancewx]

The subsurface reading for November 2020 should be around -1.1.

If you blend in the subsurface reading for Sept-Nov, it looks just like November 2020. The right image is how December would look. I'm assuming a lot of the reds down here burn off with the cooler highs this week, and the map of 2020 moves toward the subsurface blend.

[raindancewx]

NAO in November looks like it finishes around +1, essentially splitting the difference between 2007 and 2011, in terms of recent +NAO Novembers. The designation used here is top third for 1950-2019 monthly readings in November.

Positive NAO November La Ninas are pretty rare - but they look a lot like what the CFS is forecasting currently for December, but with less insane warmth everywhere. The right image is also close to the "lowest sea ice extent" cold ENSO composite of 2007, 2011, 2012, 2016.

One thing I wanted to mention - and it could be a coincidence - the +NAO November La Nina all evolve to much warmer ENSO events the next winter including 1949-50 where I didn't have NAO data but matched the pattern.

The neutral November NAO La Nina winters vary a lot with years like 1954 and 2017 both included, but overall look closer to a cooler version of the pattern on the right.

March still fits the pattern of November being a good indicator too -

[griteater]

raindance - you can get NAO data back to 1899 from climate data guide: 

https://climatedataguide.ucar.edu/sites/default/files/nao_pc_monthly.txt

https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-pc-based

 

[raindancewx]

I wanted to give an update on this idea because I consider it theoretical/experimental with so few years. It appears to be working. The low sea ice extent cold-ENSO years are much closer to November 2020 (another low-sea ice cold ENSO), and also much closer to the CFS idea for December 2020 and the +NAO November La Nina look for December than the higher sea ice years. The higher sea ice years are too cold in the East. The big area of very warm November conditions has appeared in the right spot (AZ to Michigan) at the right magnitude, with a cool spot by the NW. Not perfect, but close, and definitely closer than the higher sea ice years.

 

On 10/7/2020 at 10:24 PM, raindancewx said:

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.

 

[raindancewx]

The coldest patch of waters below the Nino zones is thinning, surfacing, and moving east since this time last month. I've zeroed out the -0.5 to 0 and 0 to +0.5 waters on both maps for a clearer comparison. 

Early December in the CPC maps looks broadly like 1959 and 1988 to me. We'll see how that goes. The 11/20-11/26 period of 2007 is also pretty similar looking to how early December is depicted. Cold December La Ninas in the East often feature a very cold Midwest early in the month - but the Midwest is favored warm.

Curious to see the weeklies on Monday. Should give a good idea of how cold November is in all the Nino zones. My guess is 25.25C in Nino 3.4 for November, but will revise if the weeklies are a lot colder/warmer on Monday. If you squint a bit, it almost looks like Nino 4 warmed a tiny bit in November too. Nino 1.2 definitely did. Nino 3.4 is probably about the same as in October.

[raindancewx]

Top SOI Matches for Sept-Nov:

SOI	Sept	Oct	Nov
1947	11.7	-1.6	8.7
1959	0.5	4.7	11.2
1960	7.6	0.3	6.8
2007	2.2	6.1	9.9
2011	11.1	9.7	12.4
2017	6.1	10.6	10.4
Blend	6.5	5.0	9.9
2020	9.9	4.4	9.2

Simple SOI Match:

SOI	Sept	Oct	Nov
1960	7.6	0.3	6.8
2011	11.1	9.7	12.4
Blend	9.4	5.0	9.6
2020	9.9	4.4	9.2

November 1947, and November 1959 were extremely cold. Nov 2017 has intense heat too far West, with the east too cold for November. So I like a blend of 1960, 2007, 2011. The 1960 inclusion gets you a "-NAO" December look to offset 2007/2011 a bit. As a blend, it looks dead on to November. I would warm up the 1960/2007/2011 look outside the NW for December since it is centered on 1992 by 1-2 degrees. Also, in recent years when that warm Montana to Florida look appears, the SW is colder - almost always - than what the CFS depicts.

[raindancewx]

For November, Nino 1.2 is likely about 21.0C on the monthly data well above the reading last month. Nino 3 is probably 23.8C or so.
Nino 3.4 should be about 25.4C. Nino 4 I'd go about 27.9C. The monthly data tends to run a bit warm of the four week averages.
The ONI value for SON will be around -1.2C using the rolling CPC 30-year average. 
Against 1951-2010 averages, it's more like -0.95C for SON.                   

               Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 04NOV2020     20.3-1.0     23.6-1.3     25.1-1.5     27.8-0.8
 11NOV2020     21.2-0.3     24.1-0.9     25.7-1.0     27.9-0.7
 18NOV2020     21.0-0.7     23.6-1.4     25.2-1.5     27.9-0.7
 25NOV2020     21.0-1.0     23.7-1.3     25.3-1.3     27.9-0.7

The waters below the Nino zones still appear to be slowly warming. Subsurface value is around -1.1 for November as I mentioned above.

[raindancewx]

New Canadian trended La Nina weaker, with colder waters shifting West over time, other than a possible brief reversal east in March.

[raindancewx]

Ocean heat content for 100-180W at the equator came in at -1.04 - a bit lower than I had it.

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

Still like this blend.

Year	Sept	Oct	Nov
1999	-1.27	-1.07	-1.48
2000	-0.12	-0.37	-0.67
2007	-1.03	-1.19	-1.19
2007	-1.03	-1.19	-1.19
2011	-1.01	-1.26	-0.92
2011	-1.01	-1.26	-0.92
Blended	-0.91	-1.06	-1.06
2020	-0.87	-1.11	-1.04

Based on 1979-2019 subsurface data for November, the subsurface implies 25.67C for the La Nina in winter (-0.9C by the CPC baseline, -0.8C against 1951-2010), +/-0.6C at 85% certainty. In other words, a strong La Nina for winter (<=25.0C) is pretty unlikely now - well less than a 15% chance going by the subsurface.

Solar activity, believe it or not finished at 34 sunspots in November. That's the highest reading for sunspot activity in over three years, since September 2017. Some of the things I look at are very sensitive to solar conditions, so will be interesting to see if it is trending it up rapidly or if it falls back for a bit. As recently as September, less than one sunspot was observed for the month overall.

 

[raindancewx]

These are likely the closest La Nina matches to November 2020 overall:

Blend	Nino 4	Nino 34	Nino 3	Nino 12	Match
1971	27.71	25.56	23.79	20.89	0.47
2011	27.80	25.52	23.98	21.09	0.49
1956	27.89	25.56	23.77	20.59	0.61
1962	27.90	25.75	23.98	20.78	0.75
1995	28.11	25.60	24.04	21.37	1.02
1984	27.79	25.52	24.11	21.52	1.06

[Fred Gossage]

On 11/30/2020 at 7:34 PM, raindancewx said:

New Canadian trended La Nina weaker, with colder waters shifting West over time, other than a possible brief reversal east in March.

Colder anomalies going more west-based as the La Nina weakens is a major positive Trans-Nino Index configuration.  I know you're a bit west to have to worry about classic severe weather, but that is a big red flag going into spring.

[raindancewx]

I'm aware of the research, but it's more of an Eastern New Mexico and east thing than for the Rio Grande Valley where I am. We do get a lot of surprisingly bad large hail events in New Mexico. I've had to get my roof and windshield fixed from hail damage several times in the past decade.

The SOI crash from 10 days ago (11/21-11/23) more of less verified here with widespread light snow bands over Northern New Mexico. Missed the airport, but I had a dusting. Some areas of town had four inches or so. This is the West Side of Albuquerque.

North of town in Rio Rancho

A lot of the mountain ski resorts should be fine when they open. I know Taos and some of the other resorts have a good base of mostly natural snow. At 11,000 feet up, the Taos Powderhorn mountain observations showed 26 inches of snow pack today, very similar to the strong Fall starts in 2013, 2015, 2018 and 2019, all 25-29 inches.

I mention the snow for a couple reasons. The La Nina snow signal is "bad" - usually in the entire Southwest. But just about all of New Mexico is running well above average. The West Side of Albuquerque had 8-14" in October, with 2-4" with this storm. They average less than the airport (9.6"), more like 6 inches. Where I am, it's more like 4-8" in October, 0-1" with the current system, and the average is closer to 12" or so. Santa Fe had 1" in September, 4-8" in October, 1-3" in November, and now 2-4" in December against 22" or so long-term. So a lot of places are already nearing their annual snow averages.

In the mountainous areas, towns like Chama and Red River get well over 100 inches with good long-term records and are at least 30-35% of the way to their final averages already, even though they'll keep seeing snow into May most years. I find New Mexico does well in La Ninas when they stop developing or start to weaken, but also about 1/3 of La Ninas that are average to good for snow here: 1970, 1971, 1973, 1974, 1983, 1984, 1988, 2000, 2011, 2016. I'm looking at those years more lately,  a lot more than the one third of very bad La Ninas out here (1933, 1950, 1955, 1975, 1995, 1999, 2005, 2008, 2017). 

The 1981-2010 baseline is ~26.75C, so the 1.4C depicted here implies 25.35 or so November. We'll see what the CPC reading is when ONI updates this week. For 1951-2010, the November average is 26.5C - so this event is still not that strong by historical standards. It's much more 2011 than 2010 right now. My winter forecast assumed a 25.5C La Nina overall for Dec-Feb, with Dec coldest of the three months by raw SSTs and Feb warmest. Looks OK so far. Generally, the La Ninas with a warmer Nino 1.2 relative to 3/3.4/4 are better here. So the depiction of the Canadian (shifting West) matches with the observations that this event is not really East based despite what DT and some of the other forecasts I've seen imply. The European initialization has even Nino 4 colder than Nino 1.2, for the actual winter, both were -0.8C for November. I've liked 2007 for a while because it started east-based in early Fall, but ended up coldest in Nino 4 for a while late winter and spring. You can compare the structure to 2017-18, when you had Nino 1.2 go near 0 to -1.5 in December - way colder than the other zones. The current event is far more likely to see additional cooling in Nino 4 while Nino 1.2 warms a lot.

[raindancewx]

QBO rose to +11 in November.

2020   -2.51   -3.20   -4.36   -5.03   -4.86   -2.78    0.34    4.78    7.95   10.80   11.15 -999.00

Still think is the decent blend. The QBO really doesn't get much higher than it is now, but it misbehaved to get here (really should be negative), so maybe we'll bust through that +16 barrier this year. Doubt it though.

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov
1961	-5.47	-0.62	0.54	2.82	6.88	7.96	6.69	5.60	6.02	7.59	8.74
2010	-16.02	-16.98	-19.68	-23.57	-26.28	-25.05	-9.84	1.45	6.58	10.83	12.16
2016	9.34	6.77	3.16	0.64	2.37	3.86	6.25	10.07	10.48	12.83	14.16
2016	9.34	6.77	3.16	0.64	2.37	3.86	6.25	10.07	10.48	12.83	14.16
2016	9.34	6.77	3.16	0.64	2.37	3.86	6.25	10.07	10.48	12.83	14.16
Blend	1.31	0.54	-1.93	-3.77	-2.46	-1.10	3.12	7.45	8.81	11.38	12.68
2020	-2.51	-3.20	-4.36	-5.03	-4.86	-2.78	0.34	4.78	7.95	10.80	11.15
Trend		down	down	down	up	up	up	up	up	up	up

Timing wise, 2016 is still a better match than 2010 in terms of the East (-)/West (+) QBO positioning and trend.

 

[raindancewx]

2007 and 2020 have been very similar all year on the western side of the La Nina. Don't really see that changing anytime. The CPC had Nino 3.4 at 25.31C (-1.19C v. 1951-2010, but much colder for the last 30 years) and Nino 4 as 27.85C (-0.54C v. 1951-2010, but much colder for the last 30 years).

The ( ) includes the 60-year anomaly in Nov with the recent stronger La Ninas since 2000.

Nov              1.2                                    3                                      3.4                                     4

2007     19.92C (-1.51C)              23.48C (-1.37C)          25.17C  (-1.32C)               27.61C  (-0.78C)

2010     20.34C (-1.09C)              23.59C (-1.26C)          25.06C  (-1.43C)                27.11C  (-1.28C)

2011     21.09C (-0.34C)              23.98C (-0.87C)          25.52C  (-0.97C)                27.80C  (-0.59C)

2020     20.86C (-0.57C)              23.88C (-0.97C)          25.31C  (-1.18C)                27.85C  (-0.54C)

 

A blend of 2007/2011 is pretty close for the four zones in November: 20.50C / 23.70C / 25.35C / 27.70C

Both 2007/2011 had +NAO looks too. I'd call the November La Nina look "central" looking as opposed to basin-wide (2010), east based or west based since Nino 4 and Nino 1.2 are nothing special.

                                                                                               

                                              

[raindancewx]

Euro says this La Nina ends in March in Nino 3.4. Nino 4 will continue to strengthen into January, but it thinks Nino 3.4 is done.

[DTWXRISK]

19 hours ago, raindancewx said:

Euro says this La Nina ends in March in Nino 3.4. Nino 4 will continue to strengthen into January, but it thinks Nino 3.4 is done.

wow  talk about a TOTAL mis  read.... Good luck with that

  this issue is  will the moderate   DEC   La Nina  have the same impact   in JAN FEB MAR   as it under goes  RAPID  weakening?

  clearly  the answer  is no

[raindancewx]

You're the one who has been expecting an east-based La Nina. Good luck with that. Trends have been running opposite for weeks now.

The plume moves from majority -0.5C or lower through March, to majority above -0.5C in April. That's the end of the La Nina on the Euro. Whether it's fast by a month, or slow by a month, doesn't really matter. I had the event peaking in Nov/Dec at the surface, Oct/Nov at the subsurface, that's still at least possible.

[40/70 Benchmark]

18 hours ago, raindancewx said:

You're the one who has been expecting an east-based La Nina. Good luck with that. Trends have been running opposite for weeks now.

The plume moves from majority -0.5C or lower through March, to majority above -0.5C in April. That's the end of the La Nina on the Euro. Whether it's fast by a month, or slow by a month, doesn't really matter. I had the event peaking in Nov/Dec at the surface, Oct/Nov at the subsurface, that's still at least possible.

Yea, it was east-based....its becoming central at this point.

Agreed.

[raindancewx]

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 07OCT2020     19.5-1.2     23.4-1.5     25.5-1.2     27.8-0.8
 14OCT2020     19.6-1.2     23.6-1.3     25.3-1.4     27.8-0.9
 21OCT2020     19.9-1.1     23.8-1.2     25.3-1.4     27.8-0.8
 28OCT2020     20.0-1.1     23.5-1.5     24.9-1.7     27.9-0.7
 04NOV2020     20.3-1.0     23.6-1.3     25.1-1.5     27.8-0.8
 11NOV2020     21.2-0.3     24.1-0.9     25.7-1.0     27.9-0.7
 18NOV2020     21.0-0.7     23.6-1.4     25.2-1.5     27.9-0.7
 25NOV2020     21.0-1.0     23.7-1.3     25.3-1.3     27.9-0.7
 02DEC2020     21.8-0.5     24.4-0.7     25.5-1.1     27.6-1.0

We're going to a Modoki La Nina event if the structure of this week keeps up. You have Nino 4 likely to take over as the coldest zone by anomaly as soon as the next few weeks, as Nino 1.2/3/3.4 warm (probably aren't really as weak as this week on a monthly basis though).

If you look at early Dec 1997, there is at least a passing resemblance to the early Dec 2020 look in the US, with Nino 1.2 much warmer (relatively) than the western zones. 

[raindancewx]

The models now say the MJO is in phase five more than neutral. It seemed like there was a strong wave before but with multiple points of strength (which got interpreted by the RMM method as Neutral), and now it is more phase five alone.

The Euro has weak progression in phase five for a while now. You can see the emergence into phase five more clearly on the Canadian side of the image.

[raindancewx]

The PDO went much more negative on the traditional Nate Mantua / JISAO index.

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

First reading below -1.0 since August 2013.

2020-06-01T00:00:00Z	-0.08
2020-07-01T00:00:00Z	-0.38
2020-08-01T00:00:00Z	-0.28
2020-09-01T00:00:00Z	-0.7
2020-10-01T00:00:00Z	-0.69
2020-11-01T00:00:00Z	-1.12

[raindancewx]

Big time downward trend in La Nina strength on the UKMet.

[raindancewx]

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 04NOV2020     20.3-1.0     23.6-1.3     25.1-1.5     27.8-0.8
 11NOV2020     21.2-0.3     24.1-0.9     25.7-1.0     27.9-0.7
 18NOV2020     21.0-0.7     23.6-1.4     25.2-1.5     27.9-0.7
 25NOV2020     21.0-1.0     23.7-1.3     25.3-1.3     27.9-0.7
 02DEC2020     21.8-0.5     24.4-0.7     25.5-1.1     27.6-1.0
 09DEC2020     22.4-0.1     24.3-0.8     25.4-1.2     27.7-0.8

I don't know if people realize, this event has actually been weaker in Nino 1.2/3 compared to 2017-18 for a while now. I would say it's easier to get canonical La Nina conditions with Nino 3/1.2 both cold. This event is much colder in the West.

 08NOV2017     20.2-1.2     23.8-1.2     25.6-1.1     28.3-0.3
 15NOV2017     20.6-1.0     23.8-1.1     25.6-1.1     28.2-0.4
 22NOV2017     20.6-1.2     23.9-1.1     25.9-0.8     28.5-0.1
 29NOV2017     20.8-1.3     23.9-1.1     25.9-0.7     28.5-0.0
 06DEC2017     20.8-1.6     24.1-1.0     25.7-0.8     28.2-0.3
 13DEC2017     21.3-1.3     24.0-1.1     25.8-0.8     28.1-0.3

2010 is still much colder than this event at the moment. But the 2007-08 event is still close in Nino 3.4/4, and it warms rapidly in Nino 1.2 after mid-December.

 03NOV2010     19.7-1.6     23.4-1.6     25.2-1.4     27.0-1.6
 10NOV2010     19.5-1.9     23.5-1.5     25.2-1.4     27.2-1.5
 17NOV2010     20.2-1.5     23.5-1.5     25.0-1.6     27.1-1.5
 24NOV2010     20.6-1.3     23.3-1.7     24.9-1.7     26.9-1.7
 01DEC2010     20.5-1.7     23.3-1.7     25.0-1.7     27.0-1.5
 08DEC2010     20.9-1.5     23.4-1.7     25.0-1.6     26.9-1.6

 07NOV2007     19.3-2.1     23.0-2.0     25.0-1.6     27.5-1.1
 14NOV2007     19.2-2.3     23.2-1.7     25.2-1.5     27.3-1.3
 21NOV2007     19.8-2.0     23.2-1.8     24.9-1.7     27.1-1.5
 28NOV2007     19.8-2.2     23.3-1.8     25.1-1.6     27.4-1.1
 05DEC2007     20.6-1.8     23.5-1.5     25.1-1.5     27.5-1.0
 12DEC2007     20.3-2.4     23.3-1.8     24.9-1.7     27.5-1.0

December 2000, 2007, 2008, 2011 are all kind of close but not quite right for the current look.

 08NOV2000     20.6-0.8     24.0-1.0     25.6-1.1     28.1-0.6
 15NOV2000     20.3-1.3     24.2-0.7     25.9-0.7     28.2-0.4
 22NOV2000     20.2-1.7     24.1-0.9     25.9-0.7     28.1-0.5
 29NOV2000     21.4-0.7     24.4-0.6     25.9-0.7     27.8-0.7
 06DEC2000     21.8-0.6     24.4-0.7     25.6-1.0     27.5-1.1

 05NOV2008     21.3 0.0     24.6-0.3     26.3-0.3     28.2-0.4
 12NOV2008     21.8 0.3     24.9-0.1     26.5-0.2     28.1-0.5
 19NOV2008     21.5-0.2     24.9-0.1     26.3-0.3     28.0-0.6
 26NOV2008     21.2-0.8     24.6-0.4     26.1-0.5     27.9-0.6
 03DEC2008     21.4-0.9     24.8-0.3     26.0-0.6     27.9-0.6
 10DEC2008     22.1-0.4     24.6-0.5     25.8-0.8     27.7-0.7

 02NOV2011     20.5-0.8     23.9-1.1     25.6-1.0     27.9-0.8
 09NOV2011     20.5-0.9     23.9-1.1     25.7-0.9     27.9-0.7
 16NOV2011     20.5-1.1     23.8-1.1     25.6-1.0     27.9-0.7
 23NOV2011     21.4-0.5     24.0-1.0     25.6-1.0     27.8-0.8
 30NOV2011     21.0-1.2     23.8-1.3     25.4-1.2     27.7-0.9
 07DEC2011     21.4-1.0     23.9-1.2     25.5-1.1     27.5-1.0

 
 06DEC2000     21.8-0.6     24.4-0.7     25.6-1.0     27.5-1.1
 12DEC2007     20.3-2.4     23.3-1.8     24.9-1.7     27.5-1.0
 10DEC2008     22.1-0.4     24.6-0.5     25.8-0.8     27.7-0.7
 07DEC2011     21.4-1.0     23.9-1.2     25.5-1.1     27.5-1.0

Blended:                  21.4                     24.1                      25.5                    27.6 

 09DEC2020     22.4-0.1     24.3-0.8     25.4-1.2     27.7-0.8

My guess is this La Nina becomes a Modoki / West-Central La Nina, with Nino 4 taking over as the coldest zone in January. For now, Nino 4 is ~5C warmer than Nino 1.2, compared to ~7C warmer than in 2017.

[StormchaserChuck!]

Last frame of subsurface has some real warming... warm March. 

[raindancewx]

The weeklies imply December is around 25.45C in Nino 3.4 so far. It was 25.31C officially for November. 

The models show Nino 3.4 warming throughout the winter. So if December finishes around 25.5C, the winter should be above that. The last winter to finish below 25.5C in Nino 3.4 was 2010-11, so this is going to be one of the longest stretches in the data without a major La Nina. For my purposes, a La Nina warmer than 25.5C in Nino 3.4 in winter isn't moderate. On the CPC ONI standard, there will probably be three trimesters below -1.0C: SON, OND, NDJ. I don't think December to February will qualify.

On the Jan Null standard, it will just barely qualify as a Moderate La Nina. Against 1951-2010 averages, it's pretty likely that only October & November are 1.0C below average or colder, with only OND likely to qualify as -1.0C or colder.

I mention all this because with the current readings and forecast warming, this event may not end up materially stronger in winter than years like 1995-96, 2011-12, or 2017-18, which all had Nino 3.4 at about 25.75C in winter. The Fall peaked more impressively than those years though, which is interesting.

 

 

 

[raindancewx]

Jamstec has an El Nino trying to develop in Nino 1.2 in Summer. Sort of like the 1996-97 to 1997-98 transition but weaker/slower.

[Eric11]

15 hours ago, raindancewx said:

Jamstec has an El Nino trying to develop in Nino 1.2 in Summer. Sort of like the 1996-97 to 1997-98 transition but weaker/slower.

Canonical/East-based Nino hasn't yet been observed since 1997-98.Considering the atomsphere state and decadal warming rate of the Central Pacific(Nino 4 region).I really doubt that the jamstec forecast will actually  realize.I agree on the opinions of a rapid decaying stage of La Nina in boreal spring(looks like PMM+ helps a lot) but I do wonder whether it will develop into a Nino event (still PDO- and cold Nino 4) even a borderline event.

[StormchaserChuck!]

Well, I believe in ENSO. 

[raindancewx]

My winter forecast included the idea that the NAO would go negative in December and then revert positive for Jan-Feb based on 'NAO analogs' which match the 2020 NAO in predictive periods to similar behaving predictive periods. Will be curious to see how that goes. The NAO is a much more important as a national feature for Jan-Apr than at other times.