2024-2025 La Nina

[40/70 Benchmark]

2 hours ago, PhiEaglesfan712 said:

Yeah, the PDO still in deep negative. I think this means we can also rule out an el nino forming in 2025-26. If one was going to form, wouldn't the PDO be heading back towards positive?

We're likely to get a 2nd year la nina, although there is a chance for an ENSO neutral.

No it doesn't...we just had a strong el nino with a deeply negative PDO last year.

[GaWx]

2 hours ago, bluewave said:

Remember that the NAO and AO have been out of sync in recent winters. Yes, most winters have had a +NAO in recent years. So it would not be a surprise if the trend continues. Most of our blocking intervals have been AO dominant with a vortex east of Greenland and a +NAO.

The main takeaway with these blocking patterns has been the propensity of the Greenland blocks to link up with the Southeast Ridge. This coming event will be no different as it’s even linking up with the Southeast Ridge during a +PNA. 
 

Forecast 
 

 

Dominant winter pattern since 15-16 favors +NAO with vortex near Iceland. But variable AO due to blocks shifting west and linking up with the Southeast Ridge. Very large AO swings have become evident between month and season.
 

AO and NAO blocking more in sync during the 2010-2013 era with more uniform 500mb blocking from Iceland to Greenland and no Southeast Ridge linkage.

Dominant winter +NAO since 15-16 

 

Variable AO with big swings 

 

 

Chris, the winter NAO bar graph that you posted is off. I reposted it below. Did you produce this or did you copy it from somewhere? Every year on the graph is -0.25 to -0.5 more negative than the actual CPC monthly tabular values, which are here:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

 

Example: your graph shows DJF 2009-10 at -2.1. But the table’s DJF averaged -1.7. So, the graph is 0.4 too negative.

Another example: your graph shows 2014-5 to be ~+1.41. But the table calculates to +1.66. So, the graph is ~0.25 too negative.

Another: your graph shows 1962-3 to be ~-1.95. But the table’s value is -1.47. So, the graph is ~0.48 too negative.
 

 Every winter is similar. I couldn’t even find one exception. Why is there this -0.25 to -0.5 discrepancy on the graph vs the table?

[bluewave]

46 minutes ago, GaWx said:

Chris, the winter NAO bar graph that you posted is off. I reposted it below. Did you produce this or did you copy it from somewhere? Every year on the graph is -0.25 to -0.5 more negative than the actual CPC monthly tabular values, which are here:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

 

Example: your graph shows DJF 2009-10 at -2.1. But the table’s DJF averaged -1.7. So, the graph is 0.4 too negative.

Another example: your graph shows 2014-5 to be ~+1.41. But the table calculates to +1.66. So, the graph is ~0.25 too negative.

Another: your graph shows 1962-3 to be ~-1.95. But the table’s value is -1.47. So, the graph is ~0.48 too negative.
 

 Every winter is similar. I couldn’t even find one exception. Why is there this -0.25 to -0.5 discrepancy on the graph vs the table?

Yes, I am aware of that. Unfortunately the charts on the NOAA site calculate a little differently from the CPC. But the theme is the same though the magnitudes are a little different. Even using the CPC we noticed a shift to stronger winter +NAOs since around 2015. But the AO has been very variable with record swings from positive to negative over this period. 
 

This link calculates a little differently from CPC. 

https://psl.noaa.gov/data/climateindices/

It would be nice if the CPC provided a way to print out the graphs. This is also why I use the 500 mb height anomaly charts to illustrate the point. Lower winter heights near Iceland since 2015 and variable heights near Greenland averaging slightly positive though as an average of big swings. The strongest blocking has actually been over the KB regions shifted toward the Russian Arctic. The vortex near Iceland has been responsible for that cold pool which shows up due to the stronger winds. 

[40/70 Benchmark]

The temp and precip anomaly plotting tool should be updated to include September 2024 soon...they are having some technical issues.

Cc:[email protected]

 

Fri, Sep 20 at 9:25 AM

 

 

Hi

Thanks for emailing. We are having unusual technical issues updating the dataset this month. We hope to have it updated soon.

Cathy Smith

answering for PSL data

Show original message

[GaWx]

35 minutes ago, bluewave said:

Yes, I am aware of that. Unfortunately the charts on the NOAA site calculate a little differently from the CPC. But the theme is the same though the magnitudes are a little different. Even using the CPC we noticed a shift to stronger winter +NAOs since around 2015. But the AO has been very variable with record swings from positive to negative over this period. 
 

This link calculates a little differently from CPC. 

https://psl.noaa.gov/data/climateindices/

It would be nice if the CPC provided a way to print out the graphs. This is also why I use the 500 mb height anomaly charts to illustrate the point. Lower winter heights near Iceland since 2015 and variable heights near Greenland averaging slightly positive though as an average of big swings. The strongest blocking has actually been over the KB regions shifted toward the Russian Arctic. The vortex near Iceland has been responsible for that cold pool which shows up due to the stronger winds. 

I just sent NOAA an email at the address provided at the graphing site about this graph vs tabular NAO value discrepancy.

[GaWx]

21 minutes ago, GaWx said:

I just sent NOAA an email at the address provided at the graphing site about this graph vs tabular NAO value discrepancy.

Wow, I got an initial response within 10 minutes! Impressive!

 

“Hi

The data used for the NAO on this page is from the cpc file

 tele_index.nh

https://ftp.cpc.ncep.noaa.gov/wd52dg/data/indices/tele_index.nh

and not the link you list. 

It appears the 2 time series differ somewhat. I am not sure what the difference is in this case. The climo could be different (most likely) or definition could be slightly different. I'll try to look into it. But we don't create either of the 2.

I hope this helps.

Cathy Smith”

——————
 The climo being different would make sense because they all missed the tabular based values about the same to the negative side.

 

[roardog]

Good job Cathy Smith for answering Americanwx questions this morning. lol

[snowman19]

[George001]

14 hours ago, 40/70 Benchmark said:

"Pretty good"? -PDO is an absolute lock.

Agree, the probability of a +PDO this winter is equivalent to the probability of the Patriots winning the superbowl this year.

[PhiEaglesfan712]

8 hours ago, 40/70 Benchmark said:

No it doesn't...we just had a strong el nino with a deeply negative PDO last year.

The difference is the subsurface was warm in the 2 summers leading up to it. We still have a cold subsurface and the PDO is even deeper negative. I just cannot see how an el nino will form under those conditions. An el nino in 2025-26 would truly be an outlier. In the previous 75 years, no year with a deep negative PDO and cold subsurface produced an el nino the following year.

[Stormchaserchuck1]

45 minutes ago, PhiEaglesfan712 said:

The difference is the subsurface was warm in the 2 summers leading up to it. We still have a cold subsurface and the PDO is even deeper negative. I just cannot see how an el nino will form under those conditions. An el nino in 2025-26 would truly be an outlier. In the previous 75 years, no year with a deep negative PDO and cold subsurface produced an el nino the following year.

There actually is a near neutral correlation, believe it or not. This is +1 year from a September PDO event:

Winter PNA for 2025-26 is also actually near 0 to the following years Fall PDO (+14-18 months).

It could also just be that the data is limited. 

I do think the ENSO subsurface cold pool orienting back west recently is a damper on El Nino chances for 25-26. 

[40/70 Benchmark]

5 hours ago, Stormchaserchuck1 said:

There actually is a near neutral correlation, believe it or not. This is +1 year from a September PDO event:

Winter PNA for 2025-26 is also actually near 0 to the following years Fall PDO (+14-18 months).

It could also just be that the data is limited. 

I do think the ENSO subsurface cold pool orienting back west recently is a damper on El Nino chances for 25-26. 

Classic case of exaggerating the importance of a new tool or morcel of info...guy has been basing his entire analog composite on subsurface. 

Frankly, I'm not really concerned with 2025-2026 ENSO at this point, but I will add that La Nina remaining modest decreases the likelihood of El Nino next year (delayed oscillation theory), which is probably related to the subsurface issue. It has utility, but I just think he is overreliant on it.

[bluewave]

This a new type of -PDO which is associated with record mid-latitude SST warming east of Japan to south of the Aleutians along with to the east of New England and Maritime Canada. This most recent phase began in 2017 following the shorter 2014 to 2016 +PDO which was also associated with a record marine heatwave known as the blob off the West Coast. So these record mid-latitude marine heatwaves are becoming associated the patterns which in the past didn’t have this type of extreme oceanic heat content. 

 

 

[PhiEaglesfan712]

20 hours ago, George001 said:

Agree, the probability of a +PDO this winter is equivalent to the probability of the Patriots winning the superbowl this year.

I will always find it amazing how the Tuck Rule game happened during the only day it snowed on an otherwise record warm winter of 2001-02.

This storm and the January 2016 blizzard are classic examples of one storm making an otherwise very warm winter season memorable.

[snowman19]

Real curious to see what the MEI does this month….with the 30 day SOI near +5, the increasingly negative PDO, developing -PMM, cooling/increased trades in region 3.4, falling IOD (at -0.07), Niña forcing reflected in the global OLR…a very well coupled system is in place. Let’s see if the new MEI reflects this….

[donsutherland1]

4 hours ago, bluewave said:

This a new type of -PDO which is associated with record mid-latitude SST warming east of Japan to south of the Aleutians along with to the east of New England and Maritime Canada. This most recent phase began in 2017 following the shorter 2014 to 2016 +PDO which was also associated with a record marine heatwave known as the blob off the West Coast. So these record mid-latitude marine heatwaves are becoming associated the patterns which in the past didn’t have this type of extreme oceanic heat content. 

 

 

Climate change is influencing patterns, particularly from large-scale marine heatwaves. The current PDO- is one example. The increased frequency of the MJO's residing in the Marine Continent phases is another. That's why some seasonal forecasting methodologies based largely on analogs (even when the variables closely fit) now consistently perform poorly.

[qg_omega]

2 hours ago, donsutherland1 said:

Climate change is influencing patterns, particularly from large-scale marine heatwaves. The current PDO- is one example. The increased frequency of the MJO's residing in the Marine Continent phases is another. That's why some seasonal forecasting methodologies based largely on analogs (even when the variables closely fit) now consistently perform poorly.

Correct, marine heatwaves have taken over the pattern

[michsnowfreak]

Throwing out an early guess for my area I'd go with a DJF mean of 0° to +2° and snowfall 100-125% of avg. Expecting lots of variability. 

[PhiEaglesfan712]

3 hours ago, snowman19 said:

Real curious to see what the MEI does this month….with the 30 day SOI near +5, the increasingly negative PDO, developing -PMM, cooling/increased trades in region 3.4, falling IOD (at -0.07), Niña forcing reflected in the global OLR…a very well coupled system is in place. Let’s see if the new MEI reflects this….

Considering the MEI is already at -0.7 (it's already achieved weak la nina status for 2024-25), I think the AS reading should be deep into moderate la nina territory, possibly even reach the strong la nina threshold.

[CurlyHeadBarrett]

19 hours ago, 40/70 Benchmark said:

Classic case of exaggerating the importance of a new tool or morcel of info...guy has been basing his entire analog composite on subsurface. 

Frankly, I'm not really concerned with 2025-2026 ENSO at this point, but I will add that La Nina remaining modest decreases the likelihood of El Nino next year (delayed oscillation theory), which is probably related to the subsurface issue. It has utility, but I just think he is overreliant on it.

So when could be El Nino, 2026-27?

[PhiEaglesfan712]

25 minutes ago, CurlyHeadBarrett said:

So when could be El Nino, 2026-27?

That's certainly possible. The thing with el ninos is that you can see them coming, but they can take years to develop. In the mid-2010s el nino, a lot of people were calling for it to happen in 2012-13, but didn't start to develop until 2014-15 and the super el nino happened in 2015-16.

The next el nino could happen in 2026-27, or it could happen in 2027-28. Whenever it happens, I think the PDO will have flipped to positive. Ideally, the subsurface will turn warm either by next summer or the summer of 2026.

[CurlyHeadBarrett]

2 minutes ago, PhiEaglesfan712 said:

That's certainly possible. The thing with el ninos is that you can see them coming, but they can take years to develop. In the mid-2010s el nino, a lot of people were calling for it to happen in 2012-13, but didn't start to develop until 2014-15 and the super el nino happened in 2015-16.

The next el nino could happen in 2026-27, or it could happen in 2027-28. Whenever it happens, I think the PDO will have flipped to positive. Ideally, the subsurface will turn warm either by next summer or the summer of 2026.

 

And what do you predict for 2025-26?

[PhiEaglesfan712]

1 hour ago, CurlyHeadBarrett said:

And what do you predict for 2025-26?

If we're going to be stuck in deep negative PDO, I really can't see anything else but a continued la nina.

[CurlyHeadBarrett]

5 minutes ago, PhiEaglesfan712 said:

If we're going to be stuck in deep negative PDO, I really can't see anything else but a continued la nina.

 

What could that imply for hurricane season?

[PhiEaglesfan712]

1 hour ago, CurlyHeadBarrett said:

What could that imply for hurricane season?

2nd year la ninas tend to have above average hurricane seasons in the Atlantic. 2008, 2011, and 2021 are especially very good examples.

[CurlyHeadBarrett]

Just now, PhiEaglesfan712 said:

2nd year la ninas tend to have above average hurricane seasons in the Atlantic. 2008, 2011, and 2021 are especially very good examples.

 

And what about 1st and 3rd year ninas?

I can see next year being a mogger season TBH, but what about hyperactive?

[PhiEaglesfan712]

1 minute ago, CurlyHeadBarrett said:

And what about 1st and 3rd year ninas?

I can see next year being a mogger season TBH, but what about hyperactive?

1st year tend to be hit and miss. However, the ones that are a hit tend to be hyperactive (1995, 2005, and 2020). 3rd year la ninas (there are only 4: 1956, 1976, 2000, and 2022) have all been underwhelming. Sometimes, a neutral season after 2 la nina years can be more active (think 2012, which was the third straight above average season).

[CurlyHeadBarrett]

5 minutes ago, PhiEaglesfan712 said:

1st year tend to be hit and miss. However, the ones that are a hit tend to be hyperactive (1995, 2005, and 2020). 3rd year la ninas (there are only 4: 1956, 1976, 2000, and 2022) have all been underwhelming. Sometimes, a neutral season after 2 la nina years can be more active (think 2012, which was the third straight above average season).

 

Which ones are misses, and the best chance of an active season generally tends to be a 2nd year la nina?

[PhiEaglesfan712]

1 hour ago, CurlyHeadBarrett said:

Which ones are misses, and the best chance of an active season generally tends to be a 2nd year la nina?

First year la ninas that were misses

1970 (2nd year la nina 1971 was near average)

1973 (2nd year la nina 1974 was below average)

1983 (2nd year la nina 1984 was near average)

2007 (2nd year la nina 2008 was active)

 

[raindancewx]

He's just using the SST matching tool from Tropical Tidbits but this is similar overall to my thoughts on the winter. Haven't written my forecast yet though. I do think the Atlantic ridging will setup somewhat west of where he shows it though.

https://www.tropicaltidbits.com/analysis/hsanalog/

I don't like 2017 as an analog - it's the most active September hurricane season since 1850, with low solar and weakly positive PDO conditions. The other years are high solar, and less active hurricane seasons with more -PDO conditions. ACE has to be 50% above normal for the rest of the season to catch up to normal. My rule is ~95%+ of seasons will finish between June-Sept and June-Sept + 60 ACE. To me it's about 50/50 that we'll hit 90 ACE.