2024-2025 La Nina

[40/70 Benchmark]

I am seeing some signs of a pretty significant +PNA/+NAO that may drive things in January, before the Aleutian ridge retrogrades and puts an end to the party for February.

[PhiEaglesfan712]

Give me +PNA/+NAO in November, and now we're talking.

[bluewave]

The September 500mb pattern so far is most similar to 2022. The 500 mb anomaly center locations are far are fairly close. But this time the Aleutian Ridge is stronger and the North Atlantic ridge east of Canada a little weaker. But its forecast to strengthen in the coming days.

 

[snowman19]

6 minutes ago, bluewave said:

The September 500mb pattern so far is most similar to 2022. The 500 mb anomaly center locations are far are fairly close. But this time the Aleutian Ridge is stronger and the North Atlantic ridge east of Canada a little weaker. But its forecast to strengthen in the coming days.

 

With the inferno SSTs from the western Aleutians over to Japan that’s no surprise

[bluewave]

16 minutes ago, snowman19 said:

With the inferno SSTs from the western Aleutians over to Japan that’s no surprise

It was the first time that the summer 500mb ridge was this strong from east of Japan to south of the Aleutians .

 

 

 

[40/70 Benchmark]

2022 is certainly a great analog. That season with a hair less amplitude out west and a bit of luck would have been okay at my place. I will take the under on that degree of amplitude out west again. I understand how everything looks, but the odds of getting that deep of a trough out west in the seasonal mean are pretty remote IMHO. Its like having everything line up for a big east coast storm and expecting a repeat of Feb 7, 1978 because of that...or having everything look great on a seasonal level and expecting 1995-1996 up and down the east coast.

[snowman19]

22 minutes ago, 40/70 Benchmark said:

2022 is certainly a great analog. That season with a hair less amplitude out west and a bit of luck would have been okay at my place. I will take the under on that degree of amplitude out west again. I understand how everything looks, but the odds of getting that deep of a trough out west in the seasonal mean are pretty remote IMHO. Its like having everything line up for a big east coast storm and expecting a repeat of Feb 7, 1978 because of that...or having everything look great on a seasonal level and expecting 1995-1996 up and down the east coast.

I’m not thinking a 2022 level RNA, but I do think we average a solidly negative PNA DJFM

[PhiEaglesfan712]

5 minutes ago, snowman19 said:

I’m not thinking a 2022 level RNA, but I do think we average a solidly negative PNA DJFM

I prefer a blend of 2007 and 2020 as my analogs. They are the best matches on the MEI.

If I were to use 2022, I'd use it as a reverse log. Everything seems to be lining up opposite. 2022 was a dissipating la nina, a warm subsurface, and a record warm August/September. This year is a possibly strengthening la nina, a cold subsurface, and a relatively cool August/September. Who knows, maybe this time we get a cold January/February (and maybe a record warm May/June):

[40/70 Benchmark]

7 minutes ago, snowman19 said:

I’m not thinking a 2022 level RNA, but I do think we average a solidly negative PNA DJFM

I agree with that...probably similarly to the NAO in that while the DM mean will be decidedly positibve (not extremely so), there will be a month that counters the mean.

[40/70 Benchmark]

6 minutes ago, PhiEaglesfan712 said:

I prefer a blend of 2007 and 2020 as my analogs. They are the best matches on the MEI.

If I were to use 2022, I'd use it as a reverse log. Everything seems to be lining up opposite. 2022 was a dissipating la nina, a warm subsurface, and a record warm August/September. This year is a possibly strengthening la nina, a cold subsurface, and a relatively cool August/September. Who knows, maybe this time we get a cold January/February (and maybe a record warm May/June):

Good luck with that, although I will say that I did not include it in my JJA H5 match composite. However, I think there are a multitude of other similarities. I have come to learn that its beneficial to be eclectic in your methodology.

[bluewave]

32 minutes ago, 40/70 Benchmark said:

2022 is certainly a great analog. That season with a hair less amplitude out west and a bit of luck would have been okay at my place. I will take the under on that degree of amplitude out west again. I understand how everything looks, but the odds of getting that deep of a trough out west in the seasonal mean are pretty remote IMHO. Its like having everything line up for a big east coast storm and expecting a repeat of Feb 7, 1978 because of that...or having everything look great on a seasonal level and expecting 1995-1996 up and down the east coast.

Just pointing out the early September pattern. Very tough to get any year to play out exactly as a previous one especially with the evident amplitude differences going back the last several months.  But I will say that some of the seasonal models lowest skill with La Nina’s in recent years seems to have been with the Western Trough details.It was one of the biggest surprises was with the 16-17 La Niña. It was as if the 15-16 super El Niño precipitation got delayed a year for California. So won’t try to pinpoint Western details this early in the game. 

[snowman19]

Good luck with that, although I will say that I did not include it in my JJA H5 match composite. However, I think there are a multitude of other similarities. I have come to learn that its beneficial to be eclectic in your methodology.

Solar doesn’t match 2020 at all

[40/70 Benchmark]

45 minutes ago, bluewave said:

Just pointing out the early September pattern. Very tough to get any year to play out exactly as a previous one especially with the evident amplitude differences going back the last several months.  But I will say that some of the seasonal models lowest skill with La Nina’s in recent years seems to have been with the Western Trough details.It was one of the biggest surprises was with the 16-17 La Niña. It was as if the 15-16 super El Niño precipitation got delayed a year for California. So won’t try to pinpoint Western details this early in the game. 

Totally agree.

44 minutes ago, snowman19 said:

Solar doesn’t match 2020 at all
 

Yea, this is the problem that I had with that w QBO/La Nina and -NAO connection we spoke about yesterday...most of those seasons in that Weenie-Europe guy's composite were low solar.

[GaWx]

1 hour ago, snowman19 said:

Solar doesn’t match 2020 at all
 

The SSN mean for Sept to date has been much lower than the 215 of Aug. That is especially the case the last 10 days, which have averaged only ~128. There’s no way to know but perhaps this is one of the reasons the tropical Atlantic is waking up and likely soon headed toward normal to above average activity. Perhaps Atlantic tropical instability is increasing and, if so, the solar downturn may be contributing to that:

2024 09 01 2024.668 182  14.5  27  35
2024 09 02 2024.671 195  20.7  26  33
2024 09 03 2024.673 180  21.2  20  23
2024 09 04 2024.676 174  26.1  21  26
2024 09 05 2024.679 181  13.1  15  20
2024 09 06 2024.682 189  13.3  19  24
2024 09 07 2024.684 168  17.8  24  29
2024 09 08 2024.687 171  18.7  20  26
2024 09 09 2024.690 156  19.1  23  26
2024 09 10 2024.693 149  12.8  24  30
2024 09 11 2024.695 153  15.4  29  34
2024 09 12 2024.698 144  11.6  24  28
2024 09 13 2024.701 118  13.1  26  31
2024 09 14 2024.704 117  10.6  24  31
2024 09 15 2024.706 100  14.1  22  27
2024 09 16 2024.709 142  16.2  22  27
2024 09 17 2024.712 141  13.4  28  36
2024 09 18 2024.714 109   9.9  24  28
2024 09 19 2024.717 109  11.1  25  31

[snowman19]

18 minutes ago, GaWx said:

The SSN mean for Sept to date has been much lower than the 215 of Aug. That is especially the case the last 10 days, which have averaged only ~128. There’s no way to know but perhaps this is one of the reasons the tropical Atlantic is waking up and likely soon headed toward normal to above average activity. Perhaps Atlantic tropical instability is increasing and, if so, the solar downturn may be contributing to that:

2024 09 01 2024.668 182  14.5  27  35
2024 09 02 2024.671 195  20.7  26  33
2024 09 03 2024.673 180  21.2  20  23
2024 09 04 2024.676 174  26.1  21  26
2024 09 05 2024.679 181  13.1  15  20
2024 09 06 2024.682 189  13.3  19  24
2024 09 07 2024.684 168  17.8  24  29
2024 09 08 2024.687 171  18.7  20  26
2024 09 09 2024.690 156  19.1  23  26
2024 09 10 2024.693 149  12.8  24  30
2024 09 11 2024.695 153  15.4  29  34
2024 09 12 2024.698 144  11.6  24  28
2024 09 13 2024.701 118  13.1  26  31
2024 09 14 2024.704 117  10.6  24  31
2024 09 15 2024.706 100  14.1  22  27
2024 09 16 2024.709 142  16.2  22  27
2024 09 17 2024.712 141  13.4  28  36
2024 09 18 2024.714 109   9.9  24  28
2024 09 19 2024.717 109  11.1  25  31

Part of it could be MJO propagation related too. Going to have to see what this newly emerged sunspot group does to the total number as well

[GaWx]

2 minutes ago, snowman19 said:

Part of it could be MJO propagation related too. Going to have to see what this newly emerged sunspot group does to the total number as well

Nothing is black and white. I’m just saying it may be one factor contributing to the tropics waking up. 

[mitchnick]

2 hours ago, GaWx said:

The SSN mean for Sept to date has been much lower than the 215 of Aug. That is especially the case the last 10 days, which have averaged only ~128. There’s no way to know but perhaps this is one of the reasons the tropical Atlantic is waking up and likely soon headed toward normal to above average activity. Perhaps Atlantic tropical instability is increasing and, if so, the solar downturn may be contributing to that:

2024 09 01 2024.668 182  14.5  27  35
2024 09 02 2024.671 195  20.7  26  33
2024 09 03 2024.673 180  21.2  20  23
2024 09 04 2024.676 174  26.1  21  26
2024 09 05 2024.679 181  13.1  15  20
2024 09 06 2024.682 189  13.3  19  24
2024 09 07 2024.684 168  17.8  24  29
2024 09 08 2024.687 171  18.7  20  26
2024 09 09 2024.690 156  19.1  23  26
2024 09 10 2024.693 149  12.8  24  30
2024 09 11 2024.695 153  15.4  29  34
2024 09 12 2024.698 144  11.6  24  28
2024 09 13 2024.701 118  13.1  26  31
2024 09 14 2024.704 117  10.6  24  31
2024 09 15 2024.706 100  14.1  22  27
2024 09 16 2024.709 142  16.2  22  27
2024 09 17 2024.712 141  13.4  28  36
2024 09 18 2024.714 109   9.9  24  28
2024 09 19 2024.717 109  11.1  25  31

Just another example of an X poster feeling compelled to try to be the first to hype something. 

[bluewave]

After the lowest August 500mb heights on record for Iceland, Greenland is getting ready to experience some of its strongest 500mb blocking on record for the month of September. We have been seeing these big swings in the AO and NAO since just after 2010. So this makes extended forecasting of those indices very tricky at any interval beyond the 1 or 2 week range. 
 

[snowman19]

Yea, this is the problem that I had with that w QBO/La Nina and -NAO connection we spoke about yesterday...most of those seasons in that Weenie-Europe guy's composite were low solar.

[mitchnick]

26 minutes ago, snowman19 said:

 

 

 

 

 

 

 

 

 

 

Assuming this year follows suit, several questions remain that can't be measured by those stats: 1) whether it will be a constant solid +NAO or will it be up and down that averages +NAO allowing for transient -NAO periods/opportunities; and 2) how positive if positive.

[Stormchaserchuck1]

5 hours ago, bluewave said:

After the lowest August 500mb heights on record for Iceland, Greenland is getting ready to experience some of its strongest 500mb blocking on record for the month of September. We have been seeing these big swings in the AO and NAO since just after 2010. So this makes extended forecasting of those indices very tricky at any interval beyond the 1 or 2 week range. 

I think that the progression favors a +NAO Winter.. It works better with Oct -NAO, but late Sept might be close enough

[Stormchaserchuck1]

2 hours ago, mitchnick said:

Assuming this year follows suit, several questions remain that can't be measured by those stats: 1) whether it will be a constant solid +NAO or will it be up and down that averages +NAO allowing for transient -NAO periods/opportunities; and 2) how positive if positive.

My NAO formula, based on data since 1948, says we have a 50% chance of having DJFM NAO 0.00 to +1.10 (per CPC calculations). Now lately we have had some Greenland ridging while the CPC calls it a +NAO, so the AO may have a better chance of being neutral to negative. But that's a pretty high SD for at least a moderately positive NAO this Winter. 

[Stormchaserchuck1]

12 hours ago, 40/70 Benchmark said:

I am seeing some signs of a pretty significant +PNA/+NAO that may drive things in January, before the Aleutian ridge retrogrades and puts an end to the party for February.

Some of these Summer patterns with warmth on the West coast do roll forward to a +pna/-epo chance for Dec and Jan. If we have a -PNA ridge, and I've talked to you about this before, a -PNA ridge due to the La Nina and -3 PDO, it may help the NAO go neutral to negative when that happens.. but I think if the +NAO is a strong signal, which it is, we may have some 10-day periods this Winter where the Pacific is favorable. most likely in Dec-Jan. 

[michsnowfreak]

2 hours ago, mitchnick said:

Assuming this year follows suit, several questions remain that can't be measured by those stats: 1) whether it will be a constant solid +NAO or will it be up and down that averages +NAO allowing for transient -NAO periods/opportunities; and 2) how positive if positive.

I doubt it would be solid +NAO. Probably up and down.

[Stormchaserchuck1]

18z GEFS has an Aleutian ridge extending to Japan Oct 1-5. Pretty good chance this is a solidly negative PDO Winter

(correlation is opposite, default is positive)

Poor New Mexico lol

[40/70 Benchmark]

2 hours ago, Stormchaserchuck1 said:

Some of these Summer patterns with warmth on the West coast do roll forward to a +pna/-epo chance for Dec and Jan. If we have a -PNA ridge, and I've talked to you about this before, a -PNA ridge due to the La Nina and -3 PDO, it may help the NAO go neutral to negative when that happens.. but I think if the +NAO is a strong signal, which it is, we may have some 10-day periods this Winter where the Pacific is favorable. most likely in Dec-Jan. 

Same page.

[40/70 Benchmark]

2 hours ago, Stormchaserchuck1 said:

18z GEFS has an Aleutian ridge extending to Japan Oct 1-5. Pretty good chance this is a solidly negative PDO Winter

(correlation is opposite, default is positive)

Poor New Mexico lol

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

[GaWx]

14 hours ago, 40/70 Benchmark said:

Totally agree.

Yea, this is the problem that I had with that w QBO/La Nina and -NAO connection we spoke about yesterday...most of those seasons in that Weenie-Europe guy's composite were low solar.

Indeed:

Here are the DJF NAOs for the 8 Niña/W winters since 1948-9 in SS order high to low

 

1999-0 +1.3 (all 3 +)(SS 140)

2022-3 +0.7 (no -)(SS 120)

1971-2  +0.4 (all 3 +)(SS 110)

2010-1 -0.7 (DJ -)(SS 30)

2016-7 +0.7 (all 3 +)(SS 20)

2020-1 -0.4 (DJ -)(SS 14)

1975-6 +0.2 (J -)(SS 10)

2008-9 -0.1 (D -)(SS 1)

 Analysis:

- The 3 highest SS winters of this group by far all had +NAO winters with not even one -NAO month

- 4 of the 5 lowest SS winters had either 1 or 2 -NAO months of the 3 with all in D and/or J interestingly enough

- Of these 8 winters, the only one out of sync was 2016-7 with its solid +NAO despite low SS

 

Conclusion:

- Kudos to Ray and @snowman19. Niña/W connection to -NAO or neutral NAO winters has been only during low sunspots with 80% (4 of 5) that way.

- Niña/W/high SS seems to favor +NAO
———-

**Edit: Aside: note there were no Niña/W winters 1948-9 through 1970-1 (vs 2 Nina/E). None of those 23 winters! A big reason was the much lower frequency of La Nina then. Then there were 2 of the next 5 that were Niña/W (1 of those was Niña/E). But then none of the subsequent 23 were Nina/W (vs 2 that were Niña/E). This was followed by 6 of the last 25 that were Niña/W (vs 6 being Niña/E) and 5 of the last 14 largely due to increased Niña frequency since the late 1990s.

[PhiEaglesfan712]

6 hours ago, 40/70 Benchmark said:

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

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.

[bluewave]

10 hours ago, Stormchaserchuck1 said:

I think that the progression favors a +NAO Winter.. It works better with Oct -NAO, but late Sept might be close enough

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