2025-2026 ENSO

[LibertyBell]

1 hour ago, 40/70 Benchmark said:

We must be turning into a tropical rain forest this decade.

Yes, way too much rain in the summer.  Fall was very dry, but usually a dry fall is a bad sign as it hints at what the winter will be like.

Some great winters after hot and dry summers 1955-56, 1966-67, 1977-78, 1993-94, 1995-96, 2002-03, 2010-11.  This is a very nice list....

[Stormchaserchuck1]

Check out this 27 year -PNA pattern we are in, in the North Pacific Ocean. This covers 324-consecutive-months to the present. 

A big reason is the frequency of La Nina during that time. 

[40/70 Benchmark]

14 hours ago, Stormchaserchuck1 said:

Check out this 27 year -PNA pattern we are in, in the North Pacific Ocean. This covers 324-consecutive-months to the present. 

A big reason is the frequency of La Nina during that time. 

1998 is when the multidecadal PDO cycle flipped negative, so makes sense...probably augmented by CC (west Pac warm pool), too.

[GaWx]

Please pin this thread and unpin the El Niño 2023-4 thread. 2024-5 La Niña thread remaining pinned is ok since it’s still active. TIA

@stormtracker

@jburns

@ORH_wxman

[FPizz]

6 minutes ago, GaWx said:

Please pin this thread and unpin the El Niño 2023-4 thread. 2024-5 La Niña thread remaining pinned is ok since it’s still active. TIA

@stormtracker

@jburns

@ORH_wxman

and maybe get rid of the spam bots

[Stormchaserchuck1]

9 hours ago, 40/70 Benchmark said:

1998 is when the multidecadal PDO cycle flipped negative, so makes sense...probably augmented by CC (west Pac warm pool), too.

I think it was a flip to more of a La Nina decadal state, because the PDO is water circulation in the North Pacific Ocean, and the Southern Hemisphere doesn't have the same water circulation... but there were High pressures on both sides of the ENSO Hadley Cell in the Northern and Southern Hemisphere's

[snowman19]

I think it was a flip to more of a La Nina decadal state, because the PDO is water circulation in the North Pacific Ocean, and the Southern Hemisphere doesn't have the same water circulation... but there were High pressures on both sides of the ENSO Hadley Cell in the Northern and Southern Hemisphere's

While we certainly appear to have already reached the “peak” of this -PDO cycle, it looks like we are still in it, probably for at least another year…..

[chubbs]

On 5/12/2025 at 4:21 PM, Stormchaserchuck1 said:

Check out this 27 year -PNA pattern we are in, in the North Pacific Ocean. This covers 324-consecutive-months to the present. 

A big reason is the frequency of La Nina during that time. 

A better pattern for cool weather in US if you restrict to  the winter months. It could have been worse.

[bluewave]

On 5/12/2025 at 4:21 PM, Stormchaserchuck1 said:

Check out this 27 year -PNA pattern we are in, in the North Pacific Ocean. This covers 324-consecutive-months to the present. 

A big reason is the frequency of La Nina during that time. 

The Aleutian Ridge prior to 2019 was much weaker on an annual basis than it was compared to 1999-2018. I separated the 1999 to 2024 years into smaller periods in order to show the progression. So this is a new pattern coinciding with the rapid expansion of marine heatwaves in recent years. Also notice how the brief relaxation of this pattern over the winter had no staying power. Now we are back to the much stronger ridging SW of the Aleutians. 
 

 

[40/70 Benchmark]

20 minutes ago, bluewave said:

The Aleutian Ridge prior to 2019 was much weaker on an annual basis than it was compared to 1999-2018. I separated the 1999 to 2024 years into smaller periods in order to show the progression. So this is a new pattern coinciding with the rapid expansion of marine heatwaves in recent years. Also notice how the brief relaxation of this pattern over the winter had no staying power. Now we are back to the much stronger ridging SW of the Aleutians. 
 

 

Heights are rising everywhere due to CC....not sure what that proves, as it isn't specific to the Aleutian ridge.

[bluewave]

1 minute ago, 40/70 Benchmark said:

Heights are rising everywhere due to CC....not sure what that proves, as it isn't specific to the Aleutian ridge.

That’s why this goes beyond the PDO and ENSO.  We didn’t used to get these mega Aleutian Ridges and Southeast Ridges during  -PDO and La Niña intervals of the past.

Plus we are getting new patterns coinciding with the marine heatwaves from the Western to Central Pacific leading to historic 2nd EOFs of the PDO. This is why the ENSO and PDO events of recent years are behaving diffferently and creating different sensible weather patterns for us. 

The much stronger Northern Stream of the Pacific Jet has shifted the winter storm track through the Great Lakes. So this has created the record low snowfall pattern for us since 2019. 

 

[40/70 Benchmark]

24 minutes ago, bluewave said:

That’s why this goes beyond the PDO and ENSO.  We didn’t used to get these mega Aleutian Ridges and Southeast Ridges during  -PDO and La Niña intervals of the past.

Plus we are getting new patterns coinciding with the marine heatwaves from the Western to Central Pacific leading to historic 2nd EOFs of the PDO. This is why the ENSO and PDO events of recent years are behaving diffferently and creating different sensible weather patterns for us. 

The much stronger Northern Stream of the Pacific Jet has shifted the winter storm track through the Great Lakes. So this has created the record low snowfall pattern for us since 2019. 

 

Okay, I agree CC is enhancing this..I thought you were implying that the Aleutian ridge has increased more than ambient heights. My only conention regarding the last part is I still think the +NAO and +WPO are playng a significant role in the low snowfall, but I don't argue that the stronger jet is having some influence as well. But it is has been a shitty pattern, regardless....+NAO/+WPO has never ended well for the east coast snow enthusiast.

[bluewave]

6 minutes ago, 40/70 Benchmark said:

Okay, I agree CC is enhancing this..I thought you were implying that the Aleutian ridge has increased more than ambient heights. My only conention regarding the last part is I still think the +NAO and +WPO are playng a significant role in the low snowfall, but I don't argue that the stronger jet is having some influence as well. But it is has been a shitty pattern, regardless....+NAO/+WPO has never ended well for the east coast snow enthusiast.

Ambient 500 mb heights have been increasing unevenly with some areas like the Aleutian Ridge seeing more increases than other areas. 

Boston’s best winter for snowfall was the record +NAO December to March in 2015. So it was less about the NAO than the deep trough over the Northeast. 

The main reason that the -NAO patterns have been underperforming for us in the 2020s is the trough that used to be present near the Northeast has been getting crowded out by the expansion of the Southeast Ridge or WAR. So even during extreme blocking events like this last winter, the storms still cut through the Great Lakes with a -5 -AO.

The -5 AO back on 2-15-25 also extended eastward over to Iceland. So it should have also registered a strong -NAO also. But maybe the higher heights further south closer to Europe affected the calculation. 

So the lack of a KU blizzard around 2-15-25 was more about the storm track through the Great Lakes and Southeast Ridge link up than it was about the blocking near Greenland and Iceland. 

 

[40/70 Benchmark]

14 minutes ago, bluewave said:

Ambient 500 mb heights have been increasing unevenly with some areas like the Aleutian Ridge seeing more increases than other areas. 

Boston’s best winter for snowfall was the record +NAO December to March in 2015. So it was less about the NAO than the deep trough over the Northeast. 

The main reason that the -NAO patterns have been underperforming for us in the 2020s is the trough that used to be present near the Northeast has been getting crowded out by the expansion of the Southeast Ridge or WAR. So even during extreme blocking events like this last winter, the storms still cut through the Great Lakes with a -5 -AO.

The -5 AO back on 2-15-25 also extended eastward over to Iceland. So it should have also registered a strong -NAO also. But maybe the higher heights further south closer to Europe affected the calculation. 

So the lack of a KU blizzard around 2-15-25 was more about the storm track through the Great Lakes and Southeast Ridge link up than it was about the blocking near Greenland and Iceland. 

 

I didn't say, nor imply that it was all about the NAO.....2015 was a more favorable pattern and featured a deeply negative WPO, which you omitted from my "+NAO and +WPO" reference. Again, the pattern is simply more hostile....I have asked you before to find me a strongly +NAO AND +WPO season that featured well above normal snowfall along the east coast. A positive +WPO is every bit as conducive to inland storm tracks as a storngly +NAO. Now, maybe this pattern is worse than it would have been 70 years ago...I don't doubt that, but this pattern still would have sucked 70 years ago.

 

+WPO & +NAO Correlate to Warmth for Most of the NE and Inland Storm Tracks

[40/70 Benchmark]

February 2015, which is when the vast majority of the record snows fell that season, featured a -1.37 WPO. (-33 DM value). This past season had a +.45 DM WPO value. The state of the west Pacific will certainly render -NAO less effective. 

[bluewave]

7 minutes ago, 40/70 Benchmark said:

I didn't say, nor imply that it was all about the NAO.....2015 was a more favorable pattern and featured a deeply negative WPO, which you omitted from my "+NAO and +WPO" reference. Again, the pattern is simply more hostile....I have asked you before to find me a strongly +NAO AND +WPO season that featured well above normal snowfall along the east coast. A positive +WPO is every bit as conducive to inland storm tracks as a storngly +NAO. Now, maybe this pattern is worse than it would have been 70 years ago...I don't doubt that, but this pattern still would have sucked 70 years ago.

 

+WPO & +NAO Correlate to Warmth for Most of the NE and Inland Storm Tracks

The high latitude blocking pattern this February was in no way hostile to snowfall in the Northeast. It was right up there with past Februaries which produced historic KU blizzards. The issue was the northward displaced storm track and record Northern Stream of the Pacific Jet. This is conjunction with the strong Southeast Ridge and warmth when the bock peaked lead to the record snows getting displaced closer to Toronto and Montreal. While it rained with 50s along the coast around NYC Metro. 

[40/70 Benchmark]

32 minutes ago, bluewave said:

The high latitude blocking pattern this February was in no way hostile to snowfall in the Northeast. It was right up there with past Februaries which produced historic KU blizzards. The issue was the northward displaced storm track and record Northern Stream of the Pacific Jet. This is conjunction with the strong Southeast Ridge and warmth when the bock peaked lead to the record snows getting displaced closer to Toronto and Montreal. While it rained with 50s along the coast around NYC Metro. 

The NAO was extrmeley positive throughout February (WPO neutralized a bit at .32), which is not hostile to the interior NE, but it is for the coast....lo and behold, this is precisely what materlized.

Go figure-

The predominantly positive NAO during the month resulted in a southwest flow event character to the vast majority of storm systems. As a consequence of the +NAO initially forcing the lobe of the PV post split to drift westward, not only was the bulk of the cold relegated to the high plains, but the signature storm of the month tracked to the west of the area. This limited the extent to which snowfall could exceed normal relative to if the NAO had been negative. 

[40/70 Benchmark]

I actually think the best example of a the PAC jet screwing the pooch was in January.

This is especially true given the presence of stronger than average Pacific jet, which combined with +NAO in the seasonal mean made it extremely difficult to sustain a +PNA ridge in the proper location long enough to facilitate the development of a major east coast snow storm. 

 

 

Here is a prime example from last winter of the Pacific jet undercutting a +PNA ridge and this tilting it positively, leading to a failed phase attempt on the east coast.

 

This was a theme of the season.

[40/70 Benchmark]

Chris, I am not arguing that your claim has no basis or validity, but I think there is some overattribution going on there.

[bluewave]

9 minutes ago, 40/70 Benchmark said:

The NAO was extrmeley positive throughout February (WPO neutralized a bit at .32), which is not hostile to the interior NE, but it is for the coast....lo and behold, this is precisely what materlized.

Go figure-

The predominantly positive NAO during the month resulted in a southwest flow event character to the vast majority of storm systems. As a consequence of the +NAO initially forcing the lobe of the PV post split to drift westward, not only was the bulk of the cold relegated to the high plains, but the signature storm of the month tracked to the west of the area. This limited the extent to which snowfall could exceed normal relative to if the NAO had been negative. 

The mid-February period was nothing resembling a +NAO Arctic blocking pattern. There was a -5SD block over the pole which extended all the way to Iceland which is textbook -AO and -NAO. This is why the long range guidance was so snowy. The raw NAO index has been skewed by the much stronger EA patterns in recent years. So the pressures to the south haven’t been as low. 

The blocking to the north hasn’t been the issue.  It’s been the expansion of the subtropical ridges both in the Eastern US and Europe. So the lack of a trough especially near Europe caused the NAO to register as a weaker negative than the -5 AO was able to register. So a function of the way the indices are calculated and not a lack of blocking to the north. 

The current batch of computer models aren’t able to handle these new weather regimes especially the further out the forecast gets. The long range very snowy model forecasts in February reflected the old patterns which did indeed produce heavy snows down to the I-95 corridor. They would have been correct in the past keying on the heavy snowfall potential with the strong blocking to our north. But as the forecast period approached the models corrected much stronger with the Pacific Jet and Southeast Ridge.

This has been a repeating theme with the models not being able to see the Southeast Ridge and Pacific Jet intensity very well beyond 5 days or so.  The model forecasts missed the further north Southeast Ridge and stronger Pacific Jet which pushed the heaviest snows down axis up into Canada with the record snows from Toronto to Montreal. 
 

 

 

[40/70 Benchmark]

6 minutes ago, bluewave said:

The mid-February period was nothing resembling a +NAO Arctic blocking pattern. There was a -5SD block over the pole which extended all the way to Iceland which is textbook -AO and -NAO. This is why the long range guidance was so snowy. The raw NAO index has been skewed by the much stronger EA patterns in recent years. So the pressures to the south haven’t been as low. 

The blocking to the north hasn’t been the issue.  It’s been the expansion of the subtropical ridges both in the Eastern US and Europe. So the lack of a trough especially near Europe caused the NAO to register as a weaker negative than the -5 AO was able to register. So a function of the way the indices are calculated and not a lack of blocking to the north. 

The current batch of computer models aren’t able to handle these new weather regimes especially the further out the forecast gets. The long range very snowy model forecasts in February reflected the old patterns which did indeed produce heavy snows down to the I-95 corridor. They would have been correct in the past keying on the heavy snowfall potential with the strong blocking to our north. But as the forecast period approached the models corrected much stronger with the Pacific Jet and Southeast Ridge.

This has been a repeating theme with the models not being able to see the Southeast Ridge and Pacific Jet intensity very well beyond 5 days or so.  The model forecasts missed the further north Southeast Ridge and stronger Pacific Jet which pushed the heaviest snows down axis up into Canada with the record snows from Toronto to Montreal. 
 

 

 

There was a brief period -NAO mid month...I didn't say the entire month was negative. 

There have always been a favorable several day windows that failed to produce...I'm not sure that warrants disregarding the NAO index. Maybe you are right and we shouldn't bother factoring in the traditional NAO value when forecasting storms, but I'm not ready to make that leap. 

[40/70 Benchmark]

I guess I should have said "averaged very positive throughout February"....that is what I meant.

My bad on that.

[bluewave]

7 minutes ago, 40/70 Benchmark said:

There was a brief period -NAO mid month...I didn't say the entire month was negative. 

There have always been a favorable several day windows that failed to produce...I'm not sure that warrants disregarding the NAO index. Maybe you are right and we shouldn't bother factoring in the traditional NAO value when forecasting storms, but I'm not ready to make that leap. 

Most of the February -5 AO daily events since the late 1960s produced KU events and not cutters within about 10 days of the event. So this is a recent phenomenon. I am saying to look at totality of the pattern for forecasting storms. Since the 500mb and Jet Stream nuances aren’t being reflected in the raw NAO values. 

[40/70 Benchmark]

9 minutes ago, bluewave said:

Most of the February -5 AO daily events since the late 1960s produced KU events and not cutters. So this is a recent phenomenon. I am saying to look at totality of the pattern for forecasting storms. Since the 500mb and Jet Stream nuances aren’t being reflected in the raw NAO values. 

"Most"....right...not all.

I actually did a very good job of doing so in relation to that particular forecast, as I never "took the cheese", so to speak. The PNA ridge was displaced too far west and off of the coast, as it was for most of the season.

https://easternmassweather.blogspot.com/2025/02/major-storm-threat-next-week-likely-to.html

[LibertyBell]

2 hours ago, 40/70 Benchmark said:

February 2015, which is when the vast majority of the record snows fell that season, featured a -1.37 WPO. (-33 DM value). This past season had a +.45 DM WPO value. The state of the west Pacific will certainly render -NAO less effective. 

February 2015 was my absolute favorite winter month on record and it even extended into March!!  We had lots of cold, lots of snow and long duration snow cover too!!

 

[brooklynwx99]

I think part of it is that back in the 2000s and 2010s, most KU setups delivered (March 2018 is a great example), and now we're seeing some flies in the ointment. sure, some of those failure modes are popping up more and more because of CC, but I think we got a bit spoiled, so now a block pops up and everyone expects a KU (I am personally guilty of this and am trying to remove this bias)

mid-Feb easily could have occurred, the ULL just became a bit sloppy and the system became more disorganized... it still delivered historic snow to VA beach, and there was also a once in a lifetime Gulf Coast storm

[40/70 Benchmark]

4 minutes ago, LibertyBell said:

February 2015 was my absolute favorite winter month on record and it even extended into March!!  We had lots of cold, lots of snow and long duration snow cover too!!

 

March 2015 $hit the bed for my area...everything supressed into the southern half of the region...was cold and dry as the epic pack slowly fossilized and eorded. Cost me a seasonal snowfall record that I was sure I was going to get.

[LibertyBell]

1 hour ago, 40/70 Benchmark said:

There was a brief period -NAO mid month...I didn't say the entire month was negative. 

There have always been a favorable several day windows that failed to produce...I'm not sure that warrants disregarding the NAO index. Maybe you are right and we shouldn't bother factoring in the traditional NAO value when forecasting storms, but I'm not ready to make that leap. 

I think the way the NAO is calculated needs to be changed.  What is traditionally considered a -NAO doesn't behave like it and isn't really a -NAO.  For example we have to divide them into -- west based vs east based vs south based vs north based.

 

[LibertyBell]

1 minute ago, 40/70 Benchmark said:

March 2015 $hit the bed for my area...everything supressed into the southern half of the region...was cold and dry as the epic pack slowly fossilized and eorded. Cost me a seasonal snowfall record that I was sure I was going to get.

wow that reminds me of what 2013-14 was here March 2014 was suppressed to the south if it weren't for that, it would have been a snowfall record here, we went from a forecast for 2 feet of snow in the first few days of March to 2 inches in about 48 hours lol.

 

[40/70 Benchmark]

3 minutes ago, brooklynwx99 said:

I think part of it is that back in the 2000s and 2010s, most KU setups delivered (March 2018 is a great example), and now we're seeing some flies in the ointment. sure, some of those failure modes are popping up more and more because of CC, but I think we got a bit spoiled, so now a block pops up and everyone expects a KU (I am personally guilty of this and am trying to remove this bias)

mid-Feb easily could have occurred, the ULL just became a bit sloppy and the system became more disorganized... it still delivered historic snow to VA beach, and there was also a once in a lifetime Gulf Coast storm

I think the system lacking cohesiveness was do at least in part of the crap PNA ridge. I agree with you, though....CC definitely isn't making it any easier, but its not the only reason.