2025-2026 ENSO

[snowman19]

@Gawx Sunspot average for October is 125. While an obvious downtrend from last year’s solar max, solar and geomag activity remain high

[bluewave]

On 10/21/2025 at 4:04 PM, Daniel Boone said:

Yeah, interesting! Quite different from my heyday Year's of Forecasting(I'm an Antique).  Makes for a tougher seasonal forecast for sure , and to some degree medium range.

This gradient between the record SST warmth east of Japan and the Arctic cold over NE Asia is driving this very fast North Pacific Jet. So it has been very challenging to sustain the -EPO and -WPO intervals for long. Prior to 2019, we would get extended -EPO and -WPO intervals instead of these rapid shifts between positive and negative states. 
 

https://downloads.psl.noaa.gov/Public/map/teleconnections/epo.reanalysis.t10trunc.1948-present.txt

 

[EastonSN+]

On 10/17/2025 at 10:47 PM, WxWatcher007 said:

I don’t post in here (I’m really just discovering this awesome thread!) but yeah, the Great Blizzard of 2013 earns its name. 1888, 1978, (October) 2011, and 2013 stand alone in meteorological exceptionalism and societal impact in CT. 

2013 was the 2nd best storm In my lifetime in CT. Received 22 inches in Norwalk CT.

The blizzard of 1996 was the only storm that i lived through with more snowfall (27 inches Norwalk CT).

[PhiEaglesfan712]

The last real -EPO/-WPO winter was 2014-15. We did get a nice -WPO interval in winter 2021-22:

2021 11 04   -1.31
2021 11 05  -20.98
2021 11 06   -7.63
2021 11 07    3.39
2021 11 08    8.04
2021 11 09  -32.10
2021 11 10  -93.68
2021 11 11 -125.89
2021 11 12  -99.82
2021 11 13  -60.12
2021 11 14  -25.64
2021 11 15  -13.71
2021 11 16  -25.31
2021 11 17  -40.49
2021 11 18  -41.37
2021 11 19  -65.80
2021 11 20 -101.84
2021 11 21  -89.64
2021 11 22  -89.38
2021 11 23 -114.97
2021 11 24  -60.54
2021 11 25    3.63
2021 11 26   -8.78
2021 11 27  -23.90
2021 11 28   18.52
2021 11 29   60.52
2021 11 30   73.79
2021 12 01   44.70
2021 12 02   10.69
2021 12 03   57.56
2021 12 04  -11.29
2021 12 05   47.68
2021 12 06  140.61
2021 12 07  152.65
2021 12 08  144.81
2021 12 09  142.25
2021 12 10   94.87
2021 12 11    5.18
2021 12 12  -42.68
2021 12 13  -20.06
2021 12 14   17.25
2021 12 15   27.18
2021 12 16   42.72
2021 12 17   37.61
2021 12 18  -16.18
2021 12 19  -65.67
2021 12 20  -86.62
2021 12 21 -167.98
2021 12 22 -157.53
2021 12 23 -155.67
2021 12 24 -183.65
2021 12 25 -150.32
2021 12 26 -103.17
2021 12 27  -76.73
2021 12 28  -43.84
2021 12 29  -17.47
2021 12 30  -37.54
2021 12 31  -58.02
2022 01 01  -90.22
2022 01 02 -180.61
2022 01 03 -213.31
2022 01 04 -213.68
2022 01 05 -221.87
2022 01 06 -187.22
2022 01 07 -144.26
2022 01 08 -122.83
2022 01 09  -86.36
2022 01 10  -42.81
2022 01 11  -19.79
2022 01 12  -27.41
2022 01 13  -27.77
2022 01 14  -27.47
2022 01 15  -54.76
2022 01 16  -89.03
2022 01 17 -127.34
2022 01 18 -163.56
2022 01 19 -171.84
2022 01 20 -163.62
2022 01 21 -108.57
2022 01 22  -35.04
2022 01 23    4.34
2022 01 24   40.36
2022 01 25   34.18
2022 01 26  -41.09
2022 01 27  -73.77
2022 01 28  -77.14
2022 01 29  -81.85
2022 01 30  -99.66
2022 01 31 -128.64
2022 02 01 -154.42
2022 02 02 -138.45
2022 02 03  -85.60
2022 02 04  -35.37
2022 02 05  -38.33
2022 02 06  -28.75
2022 02 07    7.18
2022 02 08   -1.09
2022 02 09   -8.10
2022 02 10  -67.71
2022 02 11 -122.15
2022 02 12 -142.13
2022 02 13 -179.43
2022 02 14 -159.40
2022 02 15 -172.53
2022 02 16 -148.66
2022 02 17  -92.58
2022 02 18  -62.75
2022 02 19  -70.66
2022 02 20 -104.45
2022 02 21  -75.72
2022 02 22  -37.88
2022 02 23  -11.48

 

[40/70 Benchmark]

Final ENSO update prior to go-time second week of Novie.

https://easternmassweather.blogspot.com/2025/10/official-la-nina-now-appears-likely-for.html

[snowman19]

39 minutes ago, 40/70 Benchmark said:

Final ENSO update prior to go-time second week of Novie.

https://easternmassweather.blogspot.com/2025/10/official-la-nina-now-appears-likely-for.html

Agree with your take. Given the very strong -IOD, I would not write off some additional Niña strengthening come November with the constructive interference it provides

[GaWx]

5 hours ago, snowman19 said:

This -IOD is the strongest on BOM’s weekly records, which began back in 2008…. @40/70 Benchmark
 

 It’s highly likely that the IOD is now near its lowest of this cycle per climo. Met. autumn is by far the season when they dip the furthest in a cycle.

 This is the link to NOAA monthly IODs back to 1870 (I think I got this from snowman):

https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

  Looking back to 1950, these were when the lowest cyclical monthly lows (<-0.7) were hit:

7/2016, 10/1998, 10/1996, 6/1992, 6/1989, 9/1981, 8/1980, 10/1975, 10/1974, 9/1973, 9/1971, 9/1968, 10/1964, 10/1960, 8/1959, 9/1958, 7/1956, 9/1955, 7/1954

Analysis:

-# months since 1950 with these minimums: Sept and Oct each had 6 followed by July with 3, and June and August each with 2. So, all were June-Oct. So, IOD tends to dip to lows ~3 months earlier than ENSO dips.

-With no sub -0.7 cyclical low since 1950 in Nov, it would be very surprising if the IOD didn’t rise substantially next month.

-Sub -0.7 months have been much less common since 1998 as overall average IODs have risen substantially

-Positive IOD months used to be pretty rare but since 2006, 60% have been positive. Since 2017, 70% have been positive!

-1870-1899 had 6% positive, 1900-1924 had 4%, 1925-49 had 8%. There were positives in 12% of months during the 1950s. 28% during the 1960s, and 33% during the 1970s. There was a temporary drop back to 23% during the 1980s. Then positives rose to 37% during the 1990s, 43% during the 2000s, 59% during the 2010s, and 60% during 2020-4.

 

 Does anyone know why the average IOD has risen so much since the early 1900s and continues to rise?

[snowman19]

38 minutes ago, GaWx said:

 It’s highly likely that the IOD is now near its lowest of this cycle per climo. Met. autumn is by far the season when they dip the furthest in a cycle.

 This is the link to NOAA monthly IODs back to 1870 (I think I got this from snowman):

https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

  Looking back to 1950, these were when the lowest cyclical monthly lows (<-0.7) were hit:

7/2016, 10/1998, 10/1996, 6/1992, 6/1989, 9/1981, 8/1980, 10/1975, 10/1974, 9/1973, 9/1971, 9/1968, 10/1964, 10/1960, 8/1959, 9/1958, 7/1956, 9/1955, 7/1954

Analysis:

-# months since 1950 with these minimums: Sept and Oct each had 6 followed by July with 3, and June and August each with 2. So, all were June-Oct. So, IOD tends to dip to lows ~3 months earlier than ENSO dips.

-With no sub -0.7 cyclical low since 1950 in Nov, it would be very surprising if the IOD didn’t rise substantially next month.

-Sub -0.7 months have been much less common since 1998 as overall average IODs have risen substantially

-Positive IOD months used to be pretty rare but since 2006, 60% have been positive. Since 2017, 70% have been positive!

-1870-1899 had 6% positive, 1900-1924 had 4%, 1925-49 had 8%. There were positives in 12% of months during the 1950s. 28% during the 1960s, and 33% during the 1970s. There was a temporary drop back to 23% during the 1980s. Then positives rose to 37% during the 1990s, 43% during the 2000s, 59% during the 2010s, and 60% during 2020-4.

 

 Does anyone know why the average IOD has risen so much since the early 1900s and continues to rise?

Perfectly normal “behavior” for every IOD cycle, positive or negative. They peak in Northern Hemisphere fall (usually October) then start to rise/fall and neutralize in winter. This is the strongest negative event in over 17 years

[snowman19]

For those who track the Siberian snowcover advance in October; “SAI index” (I don’t because I think it doesn’t have a good track record at all), but here is the new update from Judah Cohen….lots of bad, false info going around X right now, mostly thanks to Mark Margavage, who just the other day said it’s advancing at an all time record level

[GaWx]

5 minutes ago, snowman19 said:

For those who track the Siberian snowcover advance in October; “SAI index” (I don’t because I think it doesn’t have a good track record at all), but here is the new update from Judah Cohen….lots of bad, false info going around X right now, mostly thanks to Mark Margavage, who just the other day said it’s advancing at an all time record level
 

 Based on the last 11 years or so (back to when the SAI was first tracked in Jerry’s autumn Siberian snowcover threads), the SAI connection to a winter -AO hasn’t worked well at all. I remember that first Oct (maybe Oct of 2014) having a large SAI and getting many of us excited only to end up with a strong +AO winter.

 So, I don’t think that the SAI matters one way or the other these days. It used to correlate well, but not since it became famous. Maybe it was shy and couldn’t take the popularity. 

[snowman19]

2 hours ago, GaWx said:

 Based on the last 11 years or so (back to when the SAI was first tracked in Jerry’s autumn Siberian snowcover threads), the SAI connection to a winter -AO hasn’t worked well at all. I remember that first Oct (maybe Oct of 2014) having a large SAI and getting many of us excited only to end up with a strong +AO winter.

 So, I don’t think that the SAI matters one way or the other these days. It used to correlate well, but not since it became famous. Maybe it was shy and couldn’t take the popularity. 

I remember several years back when the record low arctic sea ice regime first started. The hype was out of control that the open waters were going to add evaporative moisture and cause all time record snowcover to build up in the arctic and result in a strongly negative AO. That theory ended up being a real massive bust and many pro mets bought into it hook, line and sinker and used it to predict a big winter that fall

[Daniel Boone]

1 hour ago, snowman19 said:

I remember several years back when the record low arctic sea ice regime first started. The hype was out of control that the open waters were going to add evaporative moisture and cause all time record snowcover to build up in the arctic and result in a strongly negative AO. That theory ended up being a real massive bust and many pro mets bought into it hook, line and sinker and used it to predict a big winter that fall

Yeah, nothing to it. 

[40/70 Benchmark]

5 hours ago, snowman19 said:

Agree with your take. Given the very strong -IOD, I would not write off some additional Niña strengthening come November with the constructive interference it provides

Yea, the healthy -IOD bolsters the case for not jumping ship due to the subsurface...I didn't get into the IOD and GLAAM here because it was just a brief updated synopsis, but I definitely will in the seasonal analysis. 

[GaWx]

15 minutes ago, 40/70 Benchmark said:

Yea, the healthy -IOD bolsters the case for not jumping ship due to the subsurface...I didn't get into the IOD and GLAAM here because it was just a brief updated synopsis, but I definitely will in the seasonal analysis. 

 I wouldn’t at all be surprised if IOD were to go positive as early as January based on past seasonal patterns and the recent positive favored IOD era we’re now in. If El Niño is going to occur next year, I’d think that would probably also help it rise.

[40/70 Benchmark]

5 minutes ago, GaWx said:

 I wouldn’t at all be surprised if IOD were to go positive as early as January based on past seasonal patterns and the recent positive favored IOD era we’re now in. If El Niño is going to occur next year, I’d think that would probably also help it rise.

Yea, I personally don't see it as a big deal, but it certainly doesn't hurt the case for an official La Niña designation.

[so_whats_happening]

7 hours ago, GaWx said:

 It’s highly likely that the IOD is now near its lowest of this cycle per climo. Met. autumn is by far the season when they dip the furthest in a cycle.

 This is the link to NOAA monthly IODs back to 1870 (I think I got this from snowman):

https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

  Looking back to 1950, these were when the lowest cyclical monthly lows (<-0.7) were hit:

7/2016, 10/1998, 10/1996, 6/1992, 6/1989, 9/1981, 8/1980, 10/1975, 10/1974, 9/1973, 9/1971, 9/1968, 10/1964, 10/1960, 8/1959, 9/1958, 7/1956, 9/1955, 7/1954

Analysis:

-# months since 1950 with these minimums: Sept and Oct each had 6 followed by July with 3, and June and August each with 2. So, all were June-Oct. So, IOD tends to dip to lows ~3 months earlier than ENSO dips.

-With no sub -0.7 cyclical low since 1950 in Nov, it would be very surprising if the IOD didn’t rise substantially next month.

-Sub -0.7 months have been much less common since 1998 as overall average IODs have risen substantially

-Positive IOD months used to be pretty rare but since 2006, 60% have been positive. Since 2017, 70% have been positive!

-1870-1899 had 6% positive, 1900-1924 had 4%, 1925-49 had 8%. There were positives in 12% of months during the 1950s. 28% during the 1960s, and 33% during the 1970s. There was a temporary drop back to 23% during the 1980s. Then positives rose to 37% during the 1990s, 43% during the 2000s, 59% during the 2010s, and 60% during 2020-4.

 

 Does anyone know why the average IOD has risen so much since the early 1900s and continues to rise?

 

2 hours ago, 40/70 Benchmark said:

Yea, the healthy -IOD bolsters the case for not jumping ship due to the subsurface...I didn't get into the IOD and GLAAM here because it was just a brief updated synopsis, but I definitely will in the seasonal analysis. 

I equate this IOD event to something similar like 2019/20 season. That IOD event was on par to some the most intense Nino events we have seen in the last ~30 years (1997/98, and 2015/16) yet when it came to oceanic temps we hit weak Nino status that year. If you look at the subsurface during this time you also had a downwelling kelvin wave in September and October making it look like we were about to really see this event go.

I think the IOD in this case simply made it so the Nina like conditions stayed around just enough versus us pushing into weak Nino territory this year. I will say though subsurface on this event is deteriorating rather fast though there is a small chance we hit a trimonthly of about -0.6.

[40/70 Benchmark]

7 minutes ago, so_whats_happening said:

 

I equate this IOD event to something similar like 2019/20 season. That IOD event was on par to some the most intense Nino events we have seen in the last ~30 years (1997/98, and 2015/16) yet when it came to oceanic temps we hit weak Nino status that year. If you look at the subsurface during this time you also had a downwelling kelvin wave in September and October making it look like we were about to really see this event go.

I think the IOD in this case simply made it so the Nina like conditions stayed around just enough versus us pushing into weak Nino territory this year. I will say though subsurface on this event is deteriorating rather fast though there is a small chance we hit a trimonthly of about -0.6.

Pretty confident you're gonna need a bigger boat. Anyway, these oscillations happened over the summer, as well....it recovered. Additionally, 2008 was not only the last year with this type of warm pool in the western subsurface, but also the last IOD that was this well defined.

Coincidence?? It's probably at least somewhat of a protective factor against a premature demise.

Anyone know what the IOD was like in 1967?