2026-2027 El Nino

[Stormchaserchuck1]

3 hours ago, Terpeast said:

So your analog is showing a huge aleutian low with a ridge over the rockies (again). How does it look over the polar domain though? If we get a -WPO/-EPO or -NAO along with that aleutian low, we just might avoid a wall to wall torch. If we get a well-timed STJ wave with cold air lurking nearby, we could score and big.

The general tendency is -H5 near the Poles, with +H5 in the mid-latitudes, but it's a pretty weak correlation (0.10-0.15) that far out. I've run several individual cities record breaking warm patterns out at different times, and that's what the constant theme is (warm mid-latitudes, -h5 near the Pole +several months time). 

[cbmclean]

3 hours ago, GaWx said:

 Even if RONI ends up peaking +1.5+, the DC area could still have a BN averaged winter based on the 2009-10, 1965-6, and 1957-8 analogs. What did these 3 analogs have in common? -NAO and -AO, both of which were lacking in nearly all of the other +1.5+ ENSO winters. It wasn’t the Pacific that made the difference as they almost always had +PNA and no -EPO/-WPO for all +1.5+ ENSO.

 So, a -NAO/-AO would appear to be the deciders. The major challenge though for getting a -NAO is going to be sunspots almost for sure still not getting down to low (say, sub 35/month). There hasn’t been even one -NAO winter since 1980 with a >35 sunspot avg! So, the odds would be heavily against a cold DC area winter should ENSO get to +1.5+. In that case, the best hope would be for a NN instead of mild DC winter. Your better hope for a cold winter would as you’d suspect be for a sub +1.5 RONI peak this fall/winter.

What is the hypothesized physical mechanism of causation between sunspots (or solar cycle in general) and high latitude blocking?

[cbmclean]

11 hours ago, Stormchaserchuck1 said:

Sorry to dwell on the Winter West Coast ridge again, but this really stands out to me as an extreme anomaly

Most extreme West Coast DJF ridge analogs

The news is, the ridge really sticks around +time in analog cases.. this is the following year:

March (not included in my visual analog picks.. yet almost as strong of an anomaly!)

April (+60dm over the SW, US is extreme!)

May

Summer (June-August)

Following Winter (26-27 analog)

^75% of the N. Hemisphere is +H5 in the following Winter, which fits a warming sequence possibly associated with El Nino. The main point is just the skew warm-general +time. 

This is the mid-latitudes the following Winter (26-27 analog)

Winter PNA DJF 25-26 was negative, so interesting that they got a #1 record warm Winter on the West coast. Monthly PNA:

-1.41
2026   0.79  -0.56

How is it possible for there to be a -PNA with that much of a western ridge?  What exactly is the definition of the PNA index?

[Winter Wizard]

1 hour ago, cbmclean said:

How is it possible for there to be a -PNA with that much of a western ridge?  What exactly is the definition of the PNA index?

It's a bit of a misconception that the PNA corresponds to a western US ridge/trough, the index actually corresponds to a much broader area per the CPC:

PNA = Z*(15°N-25°N,180-140°W)-Z*(40°N-50°N,180-140°W) +Z*(45°N-60°N,125°W-105°W)-Z*(25°N-35°N,90°W-70°W)

So in the case of December, the -PNA was mostly the result of strong troughing over western Canada, which in turn torched the Southwest US. Good reminder that the number isn't the be all, end all, you have to look at the bigger picture. 

 

[GaWx]

2 hours ago, cbmclean said:

What is the hypothesized physical mechanism of causation between sunspots (or solar cycle in general) and high latitude blocking?

I don’t know, but I believe others here can explain it.

[LakePaste25]

1 hour ago, Winter Wizard said:

It's a bit of a misconception that the PNA corresponds to a western US ridge/trough, the index actually corresponds to a much broader area per the CPC:

PNA = Z*(15°N-25°N,180-140°W)-Z*(40°N-50°N,180-140°W) +Z*(45°N-60°N,125°W-105°W)-Z*(25°N-35°N,90°W-70°W)

So in the case of December, the -PNA was mostly the result of strong troughing over western Canada, which in turn torched the Southwest US. Good reminder that the number isn't the be all, end all, you have to look at the bigger picture. 

 

 

The reverse of this also exists. A nino-style pacific jet extension that blasts warm air into Canada and the E US typically correlates to a weak +PNA. 

[GaWx]

Whew. All signs are increasingly pointing to a significant, if not strong to very strong, El Niño event. I'll have more to say in coming weeks & months, but for now I'll just say that this is increasingly likely to become a major regional-to-global climate driver in 2026-2027.

https://twitter.com/Weather_West/status/2029694752199754045?

 

 

My thoughts on this newest Euro 3.4 prog:

- They’ve generally been getting stronger the last few months.

-This run implies a super Nino peak.

-Keep in mind, however, that this is a prog of ONI, not RONI. RONI currently is ~0.5C lower. So, this implies Aug RONI to be near +2.1 -0.5 = +1.6.

-Keep in mind that the Euro has a warm bias in 3.4 of several tenths. So, a bc prog of RONI would very likely be only in the low +1s range in Sept.

[Stormchaserchuck1]

^+2c by September, which the mean Euro is predicting, has only been done twice since 1950 (1997 +2.1, and 2015 +2.2). They were the two strongest El Nino's at a later peak since 1950 (ONI). 

If you adjust -0.5 for the RONI, +2c by September would be the 8th strongest El Nino on record. 

[Stormchaserchuck1]

+1.0c popping up south of Nino 1+2 (time sensitive)

[Stormchaserchuck1]

SOI is not budging yet

5 Mar 2026	1010.85	1003.90	13.59	10.96	8.17
4 Mar 2026	1011.34	1003.15	19.53	11.31	7.65
3 Mar 2026	1010.85	1002.70	19.34	11.46	6.95
2 Mar 2026	1010.44	1002.95	16.18	11.70	6.42
1 Mar 2026	1011.79	1003.40	20.49	11.80	6.11
28 Feb 2026	1011.80	1003.50	17.10	11.49	5.74
27 Feb 2026	1011.02	1003.50	13.35	11.33	5.53

 

3 of the last 5 months have been >+10 SOI, after 31 straight months under +10 (March 2023-Sept 2025). 

In the 2023 Super El Nino, the SOI was near 0 monthly March and April. Only in May 2023 did it have its first solid negative period, when El Nino was already happening. 

Almost 32 consecutive months >0 SOI July 2020 - Feb 2023. 

[so_whats_happening]

We are starting to see the Indian ocean set up with respect to wind anomalies the El Nino like response. The kicker so far has been the lack of westerlies getting too far east and the still (weak overall) enhanced easterlies across Nino 1+2.

2023 featured a fairly broad area of westerly anomalies across 1+2 and eastern 3 around this time so it makes me think this may end up being more Central Pac oriented versus East Pac but plenty of time to discuss. I do wonder how we impact the hurricane season coming up with atmospherically we seem to be taking our time transitioning out of the Nina like state.

 

[bluewave]

The recent Euro forecast increase in El Niño strength is due to the model initializing the record February upper ocean heat content for a developing El Niño. But as always we’ll have to wait until we get past the spring forecast barrier in order to know the exact strength.

If we do get another event near or over +2 only 3 years after the 2023-2024 event, then it would be a first. The unusual and record early warming in 2023 for a developing El Niño may have signaled a shift in the PCC near Nino 1+2 leading to faster warming and more frequent stronger El Niños.  

 

[GaWx]

1 hour ago, bluewave said:

The recent Euro forecast increase in El Niño strength is due to the model initializing the record February upper ocean heat content for a developing El Niño. But as always we’ll have to wait until we get past the spring forecast barrier in order to know the exact strength.

If we do get another event near or over +2 only 3 years after the 2023-2024 event, then it would be a first. The unusual and record early warming in 2023 for a developing El Niño may have signaled a shift in the PCC near Nino 1+2 leading to faster warming and more frequent stronger El Niños.  

 

Chris, 

 per NWS Public Information Statement 26-05, the Relative Oceanic Niño index (RONI) is used for official monitoring and prediction of the El Niño-Southern Oscillation (ENSO) phenomenon.

 

 The RONI based peak of 2023-4, which has replaced ONI for official NWS monitoring, was only +1.5:

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/

[bluewave]

46 minutes ago, GaWx said:

 

Chris, 

 per NWS Public Information Statement 26-05, the Relative Oceanic Niño index (RONI) is used for official monitoring and prediction of the El Niño-Southern Oscillation (ENSO) phenomenon.

 

 The RONI based peak of 2023-4, which has replaced ONI for official NWS monitoring, was only +1.5:

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/

The Nino 1+2 based RONI was much higher and is better correlated with the global temperature jump since early 2023 with the Nino 1+2 ONI peaking over +3. The global temperature rise around the 2023-2024 El Niño was of a greater magnitude than just using a Nino 3.4 based RONI.

This may be part of the reason that the winter of 2023-2024 had the atmospheric response and North American warmth greater than past even stronger El Niños .Plus the warmth extending west of the Dateline set records for those regions also. So the totality of the warmth gave a weaker RONI reading in 3.4.

It also highlights the weakness of relying on RONI for El Niños is a warmer world. As RONI seems to be more relevant when we get La Ninas due to the SST gradient between the WPAC and EPAC.

We still aren’t completely sure why the warming started so much earlier in 2023 than any event without the El Niño warming lag that we got in the past.