2025-2026 ENSO

[bluewave]

6 minutes ago, 40/70 Benchmark said:

I would agree with the boded even independent of GW. I don't expect 100" in a month again anytime soon.

As far as your transition period statement...I agree RE the increased moisture impact, but I still think we need more time to definitively say that the ceiling is lower...especially north of metro NYC.

I would agree with you that we need time to see what the exact ceiling is in this much warmer climate absent an historic volcanic cooling event.

My guess that I have stated is that the ceiling for NYC Central Park station is under 50”.

The ceiling at Boston is probably lower than what occurred in 14-15, 95-96, and 14-15 in the 96” to 110” range.

But I believe the Boston ceiling is higher than the last 7 years. So I wouldn’t be surprised if Boston beat their snowiest season out of the last 7 when they had 54.0” in 21-22. 
 

[anthonymm]

13 minutes ago, 40/70 Benchmark said:

Well, that settles that-

We're too southernly. CT shoreline is the dividing line now. If you look at the last 7 years the snow departures from normal are drastically worse in NYC than Boston say. As I think bluewave mentioned nyc is basically past the point of no return in the temperature department. I expect the same to happen to Boston eventually, maybe in 30ish years.

[jm1220]

On 10/5/2025 at 10:28 AM, anthonymm said:

This winter is looking more and more like a worst case scenario for mid atlantic up to nyc (not sure about sne that feels borderline right now). Could be another 2022-2023 for these regions.

If we see a crazy Pacific jet slam into the west coast and knock down any sustained +PNA and destroy any phasing opportunities to bring a good storm up here, I know exactly what to expect. Hopefully in that case it’s a mild winter since the wasted useless cold last winter was ridiculous. If whatever storm we get will be rain anyway, might as well be enjoyable outside. 

[GaWx]

 The Sept QBO dropped a little further as expected and was at -24.26:

https://psl.noaa.gov/data/correlation/qbo.data

[anthonymm]

16 minutes ago, jm1220 said:

If we see a crazy Pacific jet slam into the west coast and knock down any sustained +PNA and destroy any phasing opportunities to bring a good storm up here, I know exactly what to expect. Hopefully in that case it’s a mild winter since the wasted useless cold last winter was ridiculous. If whatever storm we get will be rain anyway, might as well be enjoyable outside. 

You described verbatim what will happen. I do like a cold winter but it is frustrating to have a january 25 type scenario where you know it's cold enough to snow but you just keep getting unlucky. At least if its a january 23 type thing you know there's no chance anyway.

[jm1220]

12 minutes ago, anthonymm said:

You described verbatim what will happen. I do like a cold winter but it is frustrating to have a january 25 type scenario where you know it's cold enough to snow but you just keep getting unlucky. At least if its a january 23 type thing you know there's no chance anyway.

Last winter was torture here-nothing worse than freezing with some cirrus while watching the Deep South get slammed, then when a storm can finally make it here it turns into a SWFE (we had one decent 4-6” SWFE in Feb but that’s the exception around NYC) or cutter. I’d rather have the 22-23 scenario where like you said it was clear way out in time our window is slammed shut.

[40/70 Benchmark]

1 hour ago, bluewave said:

I would agree with you that we need time to see what the exact ceiling is in this much warmer climate absent an historic volcanic cooling event.

My guess that I have stated is that the ceiling for NYC Central Park station is under 50”.

The ceiling at Boston is probably lower than what occurred in 14-15, 95-96, and 14-15 in the 96” to 110” range.

But I believe the Boston ceiling is higher than the last 7 years. So I wouldn’t be surprised if Boston beat their snowiest season out of the last 7 when they had 54.0” in 21-22. 
 

We agree on that...ceiling is still higher than that for Boston.

[bluewave]

1 hour ago, anthonymm said:

We're too southernly. CT shoreline is the dividing line now. If you look at the last 7 years the snow departures from normal are drastically worse in NYC than Boston say. As I think bluewave mentioned nyc is basically past the point of no return in the temperature department. I expect the same to happen to Boston eventually, maybe in 30ish years.

The snowfall departures have actually been similar from DC to Boston last 7 years. 

I never mentioned any point of no return. Just that a warmer storm track and winter background temperatures will mean less snow than we used to get. 

Even in this much warmer climate we have still managed in NYC to avoid a shutout season. But places like Philly and DC have come close in recent years.

[snowman19]

@bluewave How is your MJO signal shaping up so far this month? It looks like the MJO is finally going to propagate eastward out of the IO to the Maritime Continent (phases 5-6) at the end of this month, not very strong amplitude however….

[GaWx]

33 minutes ago, snowman19 said:

@bluewave How is your MJO signal shaping up so far this month? It looks like the MJO is finally going to propagate eastward out of the IO to the Maritime Continent (phases 5-6) at the end of this month, not very strong amplitude however….

 Related to this, it does look like that starting ~10/8 that the unprecedented during 2nd half of year (back to 1974 ) ~5 1/2 week long clockwise domination of the track will finally end.

[michsnowfreak]

5 hours ago, bluewave said:

I would agree with you that we need time to see what the exact ceiling is in this much warmer climate absent an historic volcanic cooling event.

My guess that I have stated is that the ceiling for NYC Central Park station is under 50”.

The ceiling at Boston is probably lower than what occurred in 14-15, 95-96, and 14-15 in the 96” to 110” range.

But I believe the Boston ceiling is higher than the last 7 years. So I wouldn’t be surprised if Boston beat their snowiest season out of the last 7 when they had 54.0” in 21-22. 
 

This logic makes zero sense to me, as if there is some linear correlation to "if it warms this much it will snow this much less". You harp so much on the 7 years or since 2016 or whatever, as if 2015 was generations ago. Weather goes in cycles, always have and always will, and to just assume things is really kind of wild imo. Especially since in a warmer climate there is more moisture in the air. Its not some formula of "avg temp goes from this to this so snowfall goes from this to this" and as Ive said many times. I could easily argue that for areas north of 41N or so a bit warmer temps would be a boon to heavier snowfall. If you want to be technical, the Great Lakes snow has certainly increased and even outside the belts, we see snowfall in Detroit, following the record regime of 2007-2015, just barely below the longterm avg the past decade despite several warm winters. Id argue that warmer winters are snowier than the used to be.

[snowman19]

@Stormchaserchuck1 Some NAO and AO musings

[Stormchaserchuck1]

12 minutes ago, snowman19 said:

@Stormchaserchuck1 Some NAO and AO musings

 

 

September 2025 came in as the 7th consecutive +AO month. The odds of having 7-consecutive months of either direction are 1/64.. so once in 5 years. It shows that we are in a decadal +AO phase, which I believe really took a step up after the Solar Flares in May 2024. However, since 2012, the Summer AO sign as been flipping for the Winter in most cases, favoring a ridge at 90N. I wouldn't be surprised to see this 90N ridge again this Winter, but the Polar/Mid-latitude Cell puts a corresponding trough at 45N (not 40N), which may be further north than you might expect for -AO. 

[GaWx]

 In today’s version of JB’s “I want to keep my subscribers”, JB said this:

Southern Hemisphere Sept Cold Strat link to winter

“Here are the 4 warmest eastern winters since the start of the century:”

 He then shows a very warm map comprised of DJF anomalies for 2001-2, 2011-2, 2016-7, and 2022-3.

 Next, he says this: “Here is the Sept Stratosphere over the S pole at 10 mb”

 

“This is an amazing antilog to what the cold winters have looked like”

So, he’s trying to say that 2013-4, 2014-5, 2017-8, 2019-20, and 2024-5 are better analogs.

Although @snowman19wont like this, I’ll be fair and ask if JB may be onto something noteworthy. Putting it another way, is the Euro going to end up much too warm this DJF like it was in 2024-5 and 2020-1?

 Opinions?

 

[Stormchaserchuck1]

^You can do actual AAO correlations over the whole dataset, of 73 years, both signs included. https://psl.noaa.gov/data/correlation/

Lead time (months): Let the index lead, Lag time (months): Let the pattern precede an AAO phase. 

Just going with January following a Sept AAO, this looks pretty "random"

[GaWx]

13 minutes ago, Stormchaserchuck1 said:

^You can do actual AAO correlations over the whole dataset, of 73 years, both signs included. https://psl.noaa.gov/data/correlation/

Lead time (months): Let the index lead, Lag time (months): Let the pattern precede an AAO phase. 

Just going with January following a Sept AAO, this looks pretty "random"

Thanks, Chuck. Do you have the S Hemispheric map of how Sept of 2025 looked at 10 mb anomalywise? JB didn’t post it.

[Stormchaserchuck1]

4 minutes ago, GaWx said:

Thanks, Chuck. Do you have the S Hemispheric map of how Sept of 2025 looked at 10 mb anomalywise? JB didn’t post it.

[GaWx]

2 minutes ago, Stormchaserchuck1 said:

Thanks Chuck! Wow, that looks just like the 13, 14, 17, 19, and 24 composite!

[Stormchaserchuck1]

10 minutes ago, GaWx said:

Thanks Chuck! Wow, that looks just like the 13, 14, 17, 19, and 24 composite!

10mb events are usually uniform.. you'll usually get a smooth + or - mean. That's a pretty good one though, I know in the N. Hemisphere the monthly mean never really exceeds +1800m (and that one's +1100)

I will have to go through and manually make 10mb analogs.. I was incorrect in saying it's AAO. AAO is actually a 500mb anomaly, not 10mb. There isn't a known index that calculates S. Hemisphere monthly 10mb anomaly... so the roll forwards indicating "random" is not really a correct response to anomalous 10mb September. 

[snowman19]

[Stormchaserchuck1]

^Pretty strong on us getting to Weak El Nino by April-May next year. 

If you count last year as Weak Nina, this is going to be 5/6 consecutive La Nina years, and 7/10 consecutive La Nina years! Data going back to 1948 shows that such a strong streak is likely the reverse in the next 2-3 years. 

[Daniel Boone]

22 hours ago, GaWx said:

Not always though. See 2023-4, for example, which was way too cold along with most other models. They all forecasted a classic Nino Aleutian low and you probably remember that it strangely enough verified closer to a La Ninaish Aleutian high!
 
 I did and posted an analysis here of all of them back to 2017-8. I’ll recheck it asap.

Yeah true. Forgot about that oddity.

[BlizzardWx]

7 hours ago, Stormchaserchuck1 said:

^Pretty strong on us getting to Weak El Nino by April-May next year. 

If you count last year as Weak Nina, this is going to be 5/6 consecutive La Nina years, and 7/10 consecutive La Nina years! Data going back to 1948 shows that such a strong streak is likely the reverse in the next 2-3 years. 

Hopefully time to finally kill the -PDO and MJO 4-6 warm pool with that flip. 

[bluewave]

13 hours ago, michsnowfreak said:

This logic makes zero sense to me, as if there is some linear correlation to "if it warms this much it will snow this much less". You harp so much on the 7 years or since 2016 or whatever, as if 2015 was generations ago. Weather goes in cycles, always have and always will, and to just assume things is really kind of wild imo. Especially since in a warmer climate there is more moisture in the air. Its not some formula of "avg temp goes from this to this so snowfall goes from this to this" and as Ive said many times. I could easily argue that for areas north of 41N or so a bit warmer temps would be a boon to heavier snowfall. If you want to be technical, the Great Lakes snow has certainly increased and even outside the belts, we see snowfall in Detroit, following the record regime of 2007-2015, just barely below the longterm avg the past decade despite several warm winters. Id argue that warmer winters are snowier than the used to be.

What has happened since 15-16 with the general warming and 18-19 for the warmer storm tracks is not a cycle. It’s a direct shift related to the expansion of the subtropical ridging. This has lead to vast swaths of record SSTs is the mid-latitudes. A farther north storm track than we used to get.

So it’s natural in such a pattern for areas that end up south of the dominant storm tracks to experience less snow than we used to get. We have been experiencing a series of gradual shifts since the early 1980s.

But the shift that has occurred over the last decade has been the most dramatic. People expect gradual linear shifts when it comes to weather. But the climate system produces non-linear jumps once a certain temperature threshold have been crossed.

This new study really isn’t a surprise given the rapid warming of SSTs in North Pacific. But it’s good to see this new attribution technique correct the climate model errors. Similar shift in the North Atlantic so rapidly warming the climate leads to more persistent -PDO and +AMO patterns. 
 

 

https://www.colorado.edu/today/2025/08/14/human-emissions-drove-megadrought-western-us

Greenhouse gas and aerosol emissions from human activity have been driving the prolonged drought in the western United States through a complicated connection with the Pacific Ocean, according to a new CU Boulder-led study.

For more than two decades, an extreme dry spell has drained the Colorado River, devastated local farms, and intensified wildfires across the American Southwest. The new prediction, published August 13 in Nature, could help water managers region develop better water use plans or invest in infrastructure accordingly, with relief potentially still decades away.

“Our results show that the drought and ocean patterns we’re seeing today are not just natural fluctuations—they’re largely driven by human activity,” said Jeremy Klavans, postdoctoral researcher in CU Boulder’s Department of Atmospheric and Oceanic Sciences and lead author of the study.

 

Worst drought in 12 centuries

 

The drought hitting the Colorado River Basin states and California is directly linked to a climate pattern of the north Pacific Ocean, known as the Pacific decadal oscillation (PDO).

The PDO is a natural fluctuation of the Pacific that waxes and wanes every two decades or so. In its positive phase, waters in the eastern Pacific Ocean along the U.S. West Coast tend to be warmer, whereas waters near Japan are colder. In its negative phase, the pattern flips, bringing cold water to the eastern Pacific.

Since the 1990s, the PDO has been stuck in a negative phase, an unusually long stretch for a typical cycle, Klavans said.

That has had profound impacts on the United States. The cold air and water along the U.S. West Coast hold less moisture than warm air, causing a reduction in precipitation. This extended cool phase also pushed storms that would have brought water to the region farther north.

As a result, scientists estimated that about 93% of the western United States is experiencing drought, with 70% facing severe dry conditions. Prior studies have shown that the past two decades have been the driest in the American Southwest in at least 1,200 years.

Scientists had long thought that the PDO was entirely determined by natural forces, such as the heat exchanges between the ocean and the air. Even the latest report from the Intergovernmental Panel on Climate Change (IPCC), a body of experts convened by the United Nations, said the PDO is controlled by natural forces with high confidence.

If that theory was correct, the PDO should have flipped from negative to positive in 2015 after a strong El Niño event warmed the Pacific.

Instead, the PDO shifted positive for a short time following the El Niño before reverting to the negative phase again.

New reality

To understand why the PDO has been stuck, Klavans and his team used a large collection of climate simulation programs to predict what would happen in the future.  

Using a new suite of over 570 simulations, the team found that between 1870 and 1950, changes in the PDO were almost entirely driven by internal forces. But since the mid-20^th century, greenhouse gas and aerosol emissions have accounted for more than half of the variations in the PDO.

The team discovered that existing climate models tend to overestimate the role of internal factors on the PDO while underestimating the influence of external factors, such as emissions. After correcting the imbalance, the team found that emissions, and their impacts on the PDO, have been responsible for nearly all of the precipitation decline in the western United States over the past three decades.

“People have been trying for a long time to find out why this part of the country is so dry, and we have an answer for that finally,” Klavans said.

Because the same imbalance has been shown in other regions, Klavans said the study’s implications could go far beyond the Pacific. For example, the North Atlantic Oscillation, a similar fluctuation over the Atlantic Ocean, is driving drought in places like Spain. He added that improving climate models to capture the role of external forces could help scientists predict future changes in precipitation across the globe.

As for the American Southwest, the outlook is grim. If greenhouse gas emissions continue to rise, the PDO will likely remain in its negative phase, and the drought will persist for at least the next three decades, Klavans said.

“With this information, water planners could set new expectations and make proper investments in water infrastructure now, knowing this drought is here to stay,” Klavans said.  

For example, some Californian cities are already building desalination plants to turn seawater into drinking water.  

“This study can allow us to better quantify the costs of continued greenhouse gas emissions for Americans,” Klavans said. “That can only help our region plan for a better future.” 

https://www.nature.com/articles/s41586-025-09368-2

This anthropogenic influence was previously undetected because the current generation of climate models systematically underestimate the amplitude of forced climate variability. A new attribution technique that statistically corrects for this error suggests that observed PDO impacts—including the ongoing multidecadal drought in the western United States—can be largely attributed to human activity through externally forced changes in the PDO. These results indicate that we need to rethink the attribution and projection of multidecadal climate.

 

https://www.colorado.edu/today/2025/08/14/human-emissions-drove-megadrought-western-us

Greenhouse gas and aerosol emissions from human activity have been driving the prolonged drought in the western United States through a complicated connection with the Pacific Ocean, according to a new CU Boulder-led study.

For more than two decades, an extreme dry spell has drained the Colorado River, devastated local farms, and intensified wildfires across the American Southwest. The new prediction, published August 13 in Nature, could help water managers region develop better water use plans or invest in infrastructure accordingly, with relief potentially still decades away.

“Our results show that the drought and ocean patterns we’re seeing today are not just natural fluctuations—they’re largely driven by human activity,” said Jeremy Klavans, postdoctoral researcher in CU Boulder’s Department of Atmospheric and Oceanic Sciences and lead author of the study.

 

Worst drought in 12 centuries

 

The drought hitting the Colorado River Basin states and California is directly linked to a climate pattern of the north Pacific Ocean, known as the Pacific decadal oscillation (PDO).

The PDO is a natural fluctuation of the Pacific that waxes and wanes every two decades or so. In its positive phase, waters in the eastern Pacific Ocean along the U.S. West Coast tend to be warmer, whereas waters near Japan are colder. In its negative phase, the pattern flips, bringing cold water to the eastern Pacific.

Since the 1990s, the PDO has been stuck in a negative phase, an unusually long stretch for a typical cycle, Klavans said.

That has had profound impacts on the United States. The cold air and water along the U.S. West Coast hold less moisture than warm air, causing a reduction in precipitation. This extended cool phase also pushed storms that would have brought water to the region farther north.

As a result, scientists estimated that about 93% of the western United States is experiencing drought, with 70% facing severe dry conditions. Prior studies have shown that the past two decades have been the driest in the American Southwest in at least 1,200 years.

Scientists had long thought that the PDO was entirely determined by natural forces, such as the heat exchanges between the ocean and the air. Even the latest report from the Intergovernmental Panel on Climate Change (IPCC), a body of experts convened by the United Nations, said the PDO is controlled by natural forces with high confidence.

If that theory was correct, the PDO should have flipped from negative to positive in 2015 after a strong El Niño event warmed the Pacific.

Instead, the PDO shifted positive for a short time following the El Niño before reverting to the negative phase again.

New reality

To understand why the PDO has been stuck, Klavans and his team used a large collection of climate simulation programs to predict what would happen in the future.  

Using a new suite of over 570 simulations, the team found that between 1870 and 1950, changes in the PDO were almost entirely driven by internal forces. But since the mid-20^th century, greenhouse gas and aerosol emissions have accounted for more than half of the variations in the PDO.

The team discovered that existing climate models tend to overestimate the role of internal factors on the PDO while underestimating the influence of external factors, such as emissions. After correcting the imbalance, the team found that emissions, and their impacts on the PDO, have been responsible for nearly all of the precipitation decline in the western United States over the past three decades.

“People have been trying for a long time to find out why this part of the country is so dry, and we have an answer for that finally,” Klavans said.

Because the same imbalance has been shown in other regions, Klavans said the study’s implications could go far beyond the Pacific. For example, the North Atlantic Oscillation, a similar fluctuation over the Atlantic Ocean, is driving drought in places like Spain. He added that improving climate models to capture the role of external forces could help scientists predict future changes in precipitation across the globe.

As for the American Southwest, the outlook is grim. If greenhouse gas emissions continue to rise, the PDO will likely remain in its negative phase, and the drought will persist for at least the next three decades, Klavans said.

“With this information, water planners could set new expectations and make proper investments in water infrastructure now, knowing this drought is here to stay,” Klavans said.  

For example, some Californian cities are already building desalination plants to turn seawater into drinking water.  

“This study can allow us to better quantify the costs of continued greenhouse gas emissions for Americans,” Klavans said. “That can only help our region plan for a better future.” 

https://www.nature.com/articles/s41586-025-09368-2

This anthropogenic influence was previously undetected because the current generation of climate models systematically underestimate the amplitude of forced climate variability. A new attribution technique that statistically corrects for this error suggests that observed PDO impacts—including the ongoing multidecadal drought in the western United States—can be largely attributed to human activity through externally forced changes in the PDO. These results indicate that we need to rethink the attribution and projection of multidecadal changes in regional climate.

[40/70 Benchmark]

15 hours ago, snowman19 said:

@bluewave How is your MJO signal shaping up so far this month? It looks like the MJO is finally going to propagate eastward out of the IO to the Maritime Continent (phases 5-6) at the end of this month, not very strong amplitude however….

Call me crazy, but I just assumed it wasn't off to a great start since you were asking about it.

[bluewave]

14 minutes ago, 40/70 Benchmark said:

Call me crazy, but I just assumed it wasn't off to a great start since you were asking about it.

So far we are getting the weaker October MJO 5-6 amplitude from the available forecasts. This is similar to 16-17, 21-22, and 22-23.

Last October was the stronger amplitude like 20-21 and 17-18. So we got the much stronger +PNA mismatch from those winters. So the early indicators are this winter will be warmer than last winter was with a weaker PNA than last winter.

But there could still be +PNA intervals. Snowfall is tricky since the snowfall was so low anyway last winter. So I don’t  have a clear signal yet whether the smowfall will be below, similar to or above last winter. 

I will refine the snowfall forecast once we see what happens in December. If the areas around NYC are below 4” again like last years December La Niña, then it will be another below average season. 

The lower ACE this year is also following what we experienced in 2016, 2021, and 2022. Meaning that there was a step down following the higher ACE years like we saw in 2024, 2020, and 2017.

[40/70 Benchmark]

19 minutes ago, bluewave said:

So far we are getting the weaker October MJO 5-6 amplitude from the available forecasts. This is similar to 16-17, 21-22, and 22-23.

Last October was the stronger amplitude like 20-21 and 17-18. So we got the much stronger +PNA mismatch from those winters. So the early indicators are this winter will be warmer than last winter was with a weaker PNA than last winter.

But there could still be +PNA intervals. Snowfall is tricky since the snowfall was so low anyway last winter. So I don’t  have a clear signal yet whether the smowfall will be below, similar to or above last winter. 

I will refine the snowfall forecast once we see what happens in December. If the areas around NYC are below 4” again like last years December La Niña, then it will be another below average season. 

The lower ACE this year is also following what we experienced in 2016, 2021, and 2022. Meaning that there was a step down following the higher ACE years like we saw in 2024, 2020, and 2017.

I already knew the answer once snowman asked about it...like I said. I wasn't really joking. Like the NAO data he posted....looked at the poster and knew it was data that supported a +NAO. I like the guy, but the fact of the matter is that you can't go wrong using that crude method of data analysis. Just look who is posting it and save yourself the time.

It's like my 5 year old daughter...she only asks questions when she eagerly anticipates the answer.  (After hearing how good of a girl she was all day)..."daddy, am I going to get ice cream because I was a good girl"? =Hmmm...MJO looks to enter the MC phases at a pretty low amplitude..."Chris, how does your MJO indicator look so far"?

[bluewave]

2 minutes ago, 40/70 Benchmark said:

I already knew the answer once snowman asked about it...like I said. I wasn't really joking. Like the NAO data he posted....looked at the poster and knew it wa data that supported an NAO. I like the guy, but the fact of the matter is that you can't go wrong using that crude method of data anlysis. Just look who is positing it and save yourself the time.

We usually don’t get two mismatch La Niña years in a row. So I wasn’t expecting another one this year. Plus the ACE usually declines in the following years from peak seasons like last year which went 161.

[40/70 Benchmark]

I agree, Chris...this season will probably be warmer with a more negative PNA, but we are still going to get pretty pronounced +PNA period(s) IMHO.

[40/70 Benchmark]

Just now, bluewave said:

We usually don’t get two mismatch La Niña years in a row. So I wasn’t expecting another one this year. Plus the ACE usually declines in the following years fro peak seasons like last year which went 161.

I think the ACE could still finish near normal. But ike I said, I will gladly take a repeat of 2022-2023 with a compromise PNA between that year and last year. I feel that would be pretty good for my area.