2024-2025 La Nina

[40/70 Benchmark]

https://easternmassweather.blogspot.com/2024/09/consensus-aligning-with-expectations.html

[Stormchaserchuck1]

53 minutes ago, 40/70 Benchmark said:

https://easternmassweather.blogspot.com/2024/09/consensus-aligning-with-expectations.html

Good job. Those H5 composites for the Winter looks almost exactly like mine would. 

[40/70 Benchmark]

27 minutes ago, Stormchaserchuck1 said:

Good job. Those H5 composites for the Winter looks almost exactly like mine would. 

You should do an outlook this year.

[Stormchaserchuck1]

11 minutes ago, 40/70 Benchmark said:

You should do an outlook this year.

Yeah, maybe I will. I feel like a lot of what would be discussed has been posted in this thread.. will have to go back and put it all back together

[snowman19]

This new study found a connection between low arctic sea ice and the propensity for La Niña events. Could be one of the reasons why we have seen so many Niña events since the tail end of the 1990’s….

https://www.researchgate.net/publication/382327442_Wintertime_Arctic_Sea-Ice_Decline_Related_to_Multi-Year_La_Nina_Events
 

There have also been studies that found a possible link between low arctic sea ice potentiating both the Niña/-QBO/-AO/SSWEs tendency and the Niña/+QBO/+AO/lack of SSWEs response

[Terpeast]

2 hours ago, snowman19 said:

This new study found a connection between low arctic sea ice and the propensity for La Niña events. Could be one of the reasons why we have seen so many Niña events since the tail end of the 1990’s….

https://www.researchgate.net/publication/382327442_Wintertime_Arctic_Sea-Ice_Decline_Related_to_Multi-Year_La_Nina_Events

Good link, but what you said in bolded implies that low arctic ice is causing multityear ninas. That’s not what the paper is saying at all - if anything, they’re showing evidence that points to the other way around, multiyear ninas causing lower sea ice by changing the mid-lat circulation via forcing. 

Be careful with interpreting your sources.

edit: I had it flipped in the first sentence. Now corrected

[snowman19]

8 minutes ago, Terpeast said:

Good link, but what you said in bolded implies that multiyear ninas are causing low arctic ice. That’s not what the paper is saying at all - if anything, they’re showing evidence that points to the other way around, multiyear ninas causing lower sea ice by changing the mid-lat circulation via forcing. 

Be careful with interpreting your sources.

I worded it wrong. Yes, you’re right

[donsutherland1]

23 hours ago, GaWx said:

Thanks, Don. It will likely drop further tomorrow. The bottom should be tomorrow although a Wednesday bottom can’t be ruled out.

Today's preliminary NAO value is -2.751, which is well below the existing September record. It would also be the 9th lowest all-time. An even stronger NAO block occurred during October 18-22, 2002. Winter 2002-03 was an El Niño winter.

[Met1985]

32 minutes ago, donsutherland1 said:

Today's preliminary NAO value is -2.751, which is well below the existing September record. It would also be the 9th lowest all-time. An even stronger NAO block occurred during October 18-22, 2002. Winter 2002-03 was an El Niño winter.

So if I'm reading this correct Don, this would not bode well for NAO blocking during the winter months? I can't really remember when we had just decent blocking in September at all. 

[bluewave]

46 minutes ago, donsutherland1 said:

Today's preliminary NAO value is -2.751, which is well below the existing September record. It would also be the 9th lowest all-time. An even stronger NAO block occurred during October 18-22, 2002. Winter 2002-03 was an El Niño winter.

The most interesting part of this is the volatility of both the NAO and AO indices. We saw a record low Iceland 500mb height anomaly in August. Now this month one of the highest September daily 500mb height anomalies over Greenland near +500meters. This has been a theme in recent years with some of the greatest positive and negative swings over a relatively short period we have ever seen. 

[donsutherland1]

10 minutes ago, Met1985 said:

So if I'm reading this correct Don, this would not bode well for NAO blocking during the winter months? I can't really remember when we had just decent blocking in September at all. 

During La Niña winters, this would suggest a predominantly NAO+ winter. During El Niño winters, including 2002-03, it would suggest a predominantly NAO- winter. Still, the sample sizes are small, so such tendencies should be taken with a large dose of caution.

[Terpeast]

1 minute ago, donsutherland1 said:

During La Niña winters, this would suggest a predominantly NAO+ winter. During El Niño winters, including 2002-03, it would suggest a predominantly NAO- winter. Still, the sample sizes are small, so such tendencies should be taken with a large dose of caution.

For what it's worth, all ensembles (gfs, eps, cmc) point to October 2021 as a top analog in the 6-10/11-15 day forecasts at least in yesterday's 12z run. We'll see if this holds though, as bluewave said this is a volatile pattern especially in terms of the polar domain.

[donsutherland1]

2 minutes ago, bluewave said:

The most interesting part of this is the volatility of both the NAO and AO indices. We saw a record low Iceland 500mb height anomaly in August. Now this month one of the highest September daily 500mb height anomalies over Greenland near +500meters. This has been a theme in recent years with some of the greatest positive and negative swings over a relatively short period we have ever seen. 

I suspect that the low sea ice and resulting warming of the open waters is contributing to this increased volatility.

[Met1985]

5 minutes ago, donsutherland1 said:

During La Niña winters, this would suggest a predominantly NAO+ winter. During El Niño winters, including 2002-03, it would suggest a predominantly NAO- winter. Still, the sample sizes are small, so such tendencies should be taken with a large dose of caution.

Thank you Don. Much appreciated and love to continue to learn about this. As many have mentioned we are in new territory with all this is seems.  

[mitchnick]

12 hours ago, 40/70 Benchmark said:

https://easternmassweather.blogspot.com/2024/09/consensus-aligning-with-expectations.html

Nice discussion.  Fwiw, the daily Cfs2 has been slowly morphed toward a Cansips look. The Cfs2 site, which I believe can be trusted more than Cfs2 maps from other vendors but does not provide 500mb maps, has slowly brought colder air into the northern tier and southeast resulting in normal temps for the Dec-Feb period from DCA on north.

Here's the link to the site for anyone interested:

https://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2_body.html

Direct link to today's trimonthlies temps I was referring to:

https://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/usT2me3Sea.html

Today's individual monthly temps:

https://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/usT2me3Mon.html

[bluewave]

13 minutes ago, donsutherland1 said:

I suspect that the low sea ice and resulting warming of the open waters is contributing to this increased volatility.

It’s interesting that this study came out in 2009 right before the next big step up in volatility over the last 10 to 15 years. We can also add the AO which overlaps with the NAO. It does seem like more of the volatility has been evident in the AO while the winter NAO seems to be becoming more positive. 

https://www.whoi.edu/press-room/news-release/study-links-swings-in-north-atlantic-oscillation-variability-to-climate-warming/

The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions.

“When the Industrial Revolution begins and atmospheric temperature becomes warmer, the NAO takes on a much stronger pattern in longer-term behavior,” said Goodkin. “That was suspected before in the instrumental records, but this is the first time it has been documented in records from both the ocean and the atmosphere.”

The North Atlantic Oscillation is described by the NAO index, calculated as a weighted difference between the polar low and the subtropical high during the winter season. In a positive phase, both the low-pressure zone over Iceland and high pressure over the Azores are intensified, resulting in changes in the strength, incidence, and pathway of winter storms crossing the Atlantic. In a negative phase, a weak subtropical high and a weak Icelandic low results in fewer and weaker winter storms crossing on a more west-east pathway.

The NAO index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting more than a decade. An unusually long period of positive phase between 1970-2000 led to the suggestion that global warming was affecting the behavior of the NAO.

“Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.”

“As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.”

[Met1985]

4 minutes ago, bluewave said:

It’s interesting that this study came out in 2009 right before the next big step up in volatility over the last 10 to 15 years. We can also add the AO which overlaps with the NAO. It does seem like more of the volatility has been evident in the AO while the winter NAO seems to be becoming more positive. 

https://www.whoi.edu/press-room/news-release/study-links-swings-in-north-atlantic-oscillation-variability-to-climate-warming/

 

The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions.

“When the Industrial Revolution begins and atmospheric temperature becomes warmer, the NAO takes on a much stronger pattern in longer-term behavior,” said Goodkin. “That was suspected before in the instrumental records, but this is the first time it has been documented in records from both the ocean and the atmosphere.”

The North Atlantic Oscillation is described by the NAO index, calculated as a weighted difference between the polar low and the subtropical high during the winter season. In a positive phase, both the low-pressure zone over Iceland and high pressure over the Azores are intensified, resulting in changes in the strength, incidence, and pathway of winter storms crossing the Atlantic. In a negative phase, a weak subtropical high and a weak Icelandic low results in fewer and weaker winter storms crossing on a more west-east pathway.

The NAO index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting more than a decade. An unusually long period of positive phase between 1970-2000 led to the suggestion that global warming was affecting the behavior of the NAO.

“Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.”

“As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.”

I remember this back then because we had those really cold winters back to back. I remember this circulating into more violent storms across the world and the USA. Very interesting indeed.

[michsnowfreak]

27 minutes ago, donsutherland1 said:

During La Niña winters, this would suggest a predominantly NAO+ winter. During El Niño winters, including 2002-03, it would suggest a predominantly NAO- winter. Still, the sample sizes are small, so such tendencies should be taken with a large dose of caution.

In addition to the large dose of caution (as ALL things in weather forecasting should be taken with), my understanding of the NAO has really changed over the years. For those of us north of 40N, a +NAO is just as good, if not better, than a -NAO for actual storms and such.

[GaWx]

While wintertime -NAOs became relatively few and far between 1980s-present (only 6 of the last 35 winters and all with sunspots under 35) vs the frequent occurrence of such during the prior 25 winters, summertime -NAOs became frequent over the last 18 summers (2/3 of them). So, the tendencies have been highly seasonal.

[snowman19]

33 minutes ago, donsutherland1 said:

I suspect that the low sea ice and resulting warming of the open waters is contributing to this increased volatility.

There has been musings that the Arctic sea ice state is also tied into the AMO

[donsutherland1]

1 hour ago, michsnowfreak said:

In addition to the large dose of caution (as ALL things in weather forecasting should be taken with), my understanding of the NAO has really changed over the years. For those of us north of 40N, a +NAO is just as good, if not better, than a -NAO for actual storms and such.

Yes.

Temperature correlation (2000-present):

[snowman19]

@40/70 Benchmark People can kiss the east-based dreams goodbye….

 

[PhiEaglesfan712]

If I had to bet, in 12 months we'll probably still be in la nina, but the subsurface will turn warm (like 2021 and 2022). I also think the PDO will still be negative, but not in the -2's or -3's, rather in the -1's and making its way towards 0. The signs of a future el nino will be there, with the only thing left to see is if it develops in 2026-27 or 2027-28.

[40/70 Benchmark]

3 hours ago, michsnowfreak said:

In addition to the large dose of caution (as ALL things in weather forecasting should be taken with), my understanding of the NAO has really changed over the years. For those of us north of 40N, a +NAO is just as good, if not better, than a -NAO for actual storms and such.

I have just about the same correlation as you do.

[40/70 Benchmark]

On 9/23/2024 at 4:03 PM, michsnowfreak said:

I agree. Only because Im one of those who goes into Christmas mode November 1st lol. The 2006 Tigers practiced on the offday (Oct 12, 2006) between game 2 & 3 of ALCS in heavy snow showers.

Same....All Christmas once the lights go out Halloween night.

[Stormchaserchuck1]

4 hours ago, snowman19 said:

@40/70 Benchmark People can kiss the east-based dreams goodbye….

Actually, you might be able to kiss this La Nina goodbye.. those are some weak subsurface anomalies.

[40/70 Benchmark]

14 minutes ago, Stormchaserchuck1 said:

Actually, you might be able to kiss this La Nina goodbye.. those are some weak subsurface anomalies.

I don't agree. 

[donsutherland1]

39 minutes ago, Stormchaserchuck1 said:

Actually, you might be able to kiss this La Nina goodbye.. those are some weak subsurface anomalies.

La Niña is on the cusp of developing. Region 3.4 anomalies have fallen to -0.5°C in the most recent weekly average. A weak La Niña and potentially borderline moderate one still seems on course during the latter part of the fall and during the winter.

[Stormchaserchuck1]

The subsurface has been leading the surface +3-4 months for a while now. It started weaking a little over a month ago, and it seems the current trend is for it to moderate. 

The SOI never broke +4 for the La Nina event until recently. Even now the 30-day is only +3. Gawx has posted about how this factor is correlated to the surface. It also seems to be leading. 

The Fall is typically when ENSO events deepen, but I think in the Winter it may neutralize pretty quickly.  We might not get 5 months of <-0.5 ONI for an official La Nina, but it will be close. 

Glad to see donsutherland posting more in this thread. 

[40/70 Benchmark]

1 hour ago, donsutherland1 said:

La Niña is on the cusp of developing. Region 3.4 anomalies have fallen to -0.5°C in the most recent weekly average. A weak La Niña and potentially borderline moderate one still seems on course during the latter part of the fall and during the winter.

Absolutely agree.