2024-2025 La Nina

[so_whats_happening]

30 minutes ago, bluewave said:

This was a new type of global temperature response during an El Niño. It was the first time the global temperatures rose before the El Niño fully developed like we saw last spring. Now the warming is lingering past the Nino peak which was during the winter. May be related to the ongoing marine heatwaves outside the traditional ONI SST regions.

 

 

Im not so sure because we have had this strong -PDO/ marine heatwave for some years now all it did to temps was hold serve so temps were not cooling as much as they should have the heatwaves have not effectively added more heat to the system.

I would agree though that the heatwaves probably help maintain temps though and don't allow nearly as much cooling as what should have occurred. This massive spike though was definitely the makings of something else.

Just look back at 1998, we saw an almost .6C spike similar to this one but we weren't dealing with the marine heatwaves like we are now.

[so_whats_happening]

9 minutes ago, snowman19 said:

I think this current record spike in the upper tropospheric temps is the result of a few things….Hunga Tonga, last year’s very strong El Niño and the high solar flux/high UV that’s occurring right now 

@so_whats_happening

Yea forgot to add in the solar aspect. It would be something to see very little in the way of cooling if any at all with this mini Nina (so far) event. In fact if we somehow manage to keep adding more to temps there is definitely something to worry about.

[mitchnick]

2 hours ago, snowman19 said:

This is troubling, this is the same effect we saw back in 2001 from that high solar onslaught. The high incoming UV from this major solar flux/record number of sunspots is heating the upper atmosphere. This mid-latitude upper atmospheric heating from UV is what caused the SPV to shrink and strengthen and in turn lead to ++AO back in ‘01. Then we saw the raging westerly zonal flow take over for months
 

Looks pretty consistent to me when you go back further in history. We're in a warming period. Nbd.

[bluewave]

57 minutes ago, so_whats_happening said:

Im not so sure because we have had this strong -PDO/ marine heatwave for some years now all it did to temps was hold serve so temps were not cooling as much as they should have the heatwaves have not effectively added more heat to the system.

I would agree though that the heatwaves probably help maintain temps though and don't allow nearly as much cooling as what should have occurred. This massive spike though was definitely the makings of something else.

Just look back at 1998, we saw an almost .6C spike similar to this one but we weren't dealing with the marine heatwaves like we are now.

My guess is that it’s an additive process. When El Niño and subtropical marine heatwaves combine it has greater warming potential for the global temperatures. Then as we head into La Niña the cooling is less impressive since the marine heatwaves in other areas are ongoing. So El Niño and La Niña are having to compete with marine heatwaves in other areas. Notice how this was the first borderline super El Niño with so much SST warmth from 20°to 60°N. It’s much more pronounced than it was after the 15-16 super El Niño. One theory is that it’s a reduction in shipping aerosols but there are many competing papers on the topic. May take a while for some type of consensus to form on the exact cause of the accelerated warming. 
 

 

[FPizz]

1 hour ago, mitchnick said:

Looks pretty consistent to me when you go back further in history. We're in a warming period. Nbd.

You're going to get yelled at for this graph.    

[snowman19]

[PhiEaglesfan712]

On 8/2/2024 at 1:15 PM, bluewave said:

My guess is that it’s an additive process. When El Niño and subtropical marine heatwaves combine it has greater warming potential for the global temperatures. Then as we head into La Niña the cooling is less impressive since the marine heatwaves in other areas are ongoing. So El Niño and La Niña are having to compete with marine heatwaves in other areas. Notice how this was the first borderline super El Niño with so much SST warmth from 20°to 60°N. It’s much more pronounced than it was after the 15-16 super El Niño. One theory is that it’s a reduction in shipping aerosols but there are many competing papers on the topic. May take a while for some type of consensus to form on the exact cause of the accelerated warming. 
 

 

I hate that the graph cuts off at 2010, so we don't get to see the entire picture of that first strong el nino in full. I wish they had started in 2009. But the fact that the 2019-20 (a year with barely an el nino) had more red than the start of 2010 (at the peak of a strong el nino) should tell you all you need to know about global warming in the 2010s decade.

[snowman19]

On 8/1/2024 at 1:39 PM, brooklynwx99 said:

if we are indeed using RONI over ONI, wouldn't a cold neutral ONI reading act like a weak La Nina? for example, if we bottom out at -0.3, the RONI could very well be around -0.7. the RONI was -0.25 at the lowest in DJF 2002, so I'm not sure that this logic works if the cold neutral ONI forecasts indeed verify
if we really want to use cold neutral analogs like 2001-02, we would probably actually have a warm neutral ONI around +0.2 that "acts" like a -0.3 winter given RONI cooling things down
not to say that 2001-02 is a bad analog by the way, it's not

Was looking at it more today, if there is a Niña, I’m starting to think ONI stays weak, which wouldn’t make 07-08 (I know Ray likes that one) and 16-17 bad. The big problem with 16-17 is the PDO and PMM don’t match (both were positive back then), the +QBO does match however as does the -IOD, +AMO and the MJO 4-6 Niña forcing. The best solar match is still 01-02, very good solar match actually and if it stays cold-neutral would definitely be a good ENSO match and would also match all the other background states we have now

 

 

 

 

[bluewave]

13 hours ago, PhiEaglesfan712 said:

I hate that the graph cuts off at 2010, so we don't get to see the entire picture of that first strong el nino in full. I wish they had started in 2009. But the fact that the 2019-20 (a year with barely an el nino) had more red than the start of 2010 (at the peak of a strong el nino) should tell you all you need to know about global warming in the 2010s decade.

This chart goes back much further and shows how the recent warming of the WPAC is unprecedented.

 

 

Remarkable Changes in the Dominant Modes of North Pacific Sea Surface Temperature

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078

The second PC is mostly positive from 1990 to 2021 and strongly positive from 2014 to 2021 (Figure 6b), reflecting the positive SSTa across much of the North Pacific that EOF 1 alone does not capture. The weak negative lobe in the second EOF lessens the warming near the coast of North America. As EOF 2 describes less of the variance than EOF 1, it might be expected that its shape is more variable when calculated over different time periods, interestingly, the positive lobe in EOF 2 has grown steadily when calculated over successively longer time periods (Figure 6b, x-ticks). The positive lobe of EOF 2 filled up 98% of the North Pacific when calculated over the period 1950–2018 and similarly for HadISST data at 93% (Figure S1.6 in Supporting Information S1). While EOF 2 has not been invoked as often as the PDO as a measure of SST variability, the robust evolution since 2014 is still worthy of note.

Figure 6

Open in figure viewerPowerPoint

(a) The second EOF of SST over the PDO region for the entire time series (1950–2021). (b) The principal component for the second EOF is shown on the left y-axis using colored bars. The right y-axis (x symbols) shows the percentage of data points greater than zero in the second EOF from 1970 to 2021.

5 Conclusions

The fundamental result of this study is that the first EOF of SST in the North Pacific has changed starting in 2014. For more than 20 years, the PDO has been used to describe the state of the North Pacific. However, since the marine heatwave of 2014, there have been remarkable changes to the dominant mode of SST in the North Pacific. The spatial pattern of the first EOF of SST from 1950 to 2021 is notably different from the PDO, suggesting that though the PDO served as a useful metric of SST variations until 2014 (Johnstone & Mantua, 2014), it may no longer be as effective a climate index for the North Pacific. From 1950 until the 2014 MHW, the first EOF remained consistent in its proportion of positive and negative regions with both taking up roughly half the area of the North Pacific (and with the positive region taken to be the eastern Pacific). When EOFs are calculated from 1950 to endpoints after 2014, the first EOF has a maximum positive region covering 77% of the North Pacific, with a PC indicating the largest anomalies on record. These changes to the first EOF/PC of North Pacific SST are nothing short of remarkable.

In concert with these changes, the second EOF/PC of SST has also undergone profound evolution since 2014. This second EOF now accounts for approximately 18% of the variability, growing from 13% during the 1950–2013 period. The spatial structure of the second EOF now is positive over almost the entire basin, with a PC that has grown strongly positive in the last several years. Thus, the second EOF/PC describes warming over much of the Pacific not in the positive lobe of the first EOF.

A relevant aspect of our analysis is that we did not remove a trend from the data before calculating the EOFs and PCs. This is consistent with the original calculations of EOFs in the North Pacific (Davis, 1976) and more recent analysis by Johnstone and Mantua (2014), but inconsistent with the definition of the PDO which did have a global mean trend removed (Mantua et al., 1997; Zhang et al., 1997). Whether or not a trend was removed had little effect on the first EOF, and thus the PDO, until 2014. Two of our results lead to this conclusion: first, our first PC calculated between 1950 and 1993 agreed with the PDO with a correlation coefficient of 0.97; and second, our first EOF calculated with successively longer time series did not change in shape until 2014. There are many approaches to removing a trend from time series (Deser & Phillips, 2021; Frankignoul et al., 2017; Solomon & Newman, 2012). We investigated two of these approaches: first we removed a least-squares fit of a line to the global average temperature as in the original definition of the PDO (Figure S2 in Supporting Information S1), and second, we removed a least-squares fit of a line from each grid point in the North Pacific (Figure S3 in Supporing Information S1). In each case the EOF analysis reproduced the PDO spatial pattern and index, suggesting that the PDO remains a good measure for the variability relative to the trend. In general, removal of a trend (as by least-squares fitting of a line, e.g.,) tends to deemphasize the ends of a record. In our analysis, the inclusion of the trend highlights the fact that the warming in the eastern Pacific has increased notably in recent years, a fact that would be obscured if a linear trend had been removed.

The PDO is recognized to be a result of many processes that may cause temperature variability (Newman et al., 2016) rather than any singular phenomenon. The many processes that affect SST have apparently combined to create both this era of frequent marine heatwaves beginning in 2014 and a fundamental change to the first mode of SST. The persistence of the marine heatwaves was studied by Di Lorenzo and Mantua (2016) who also invoked a number of interacting processes, suggesting that the variance described by the PDO would increase in a warmer climate. Di Lorenzo and Mantua (2016) explicitly removed a trend before calculating the EOFs of SST, so that their EOFs described variance relative to the trend. The PDO is based on a constant spatial pattern defined by the EOF that described the most variance of SST through the mid 1990's. However, there is no guarantee that the EOFs of SST will remain constant as climate change continues. This concern about indices based on EOFs applies also to the North Pacific Gyre Oscillation (Di Lorenzo et al., 2008), which describes variance in sea surface height.

The PDO is widely used as a measure of temperature in the eastern boundary upwelling system along the west coast of North America (e.g., Weber et al., 2021). The period of persistent marine heatwaves since 2014 has made the PDO less useful as an index of temperature in this region because it does not reflect the recent increase. In general, using PCs from a basin-wide analysis as indices of temperature for specific regions may be problematic because the influences from distant parts of the basin affect the PCs. Options moving forward may include: (a) updating the definition of the first mode of temperature variability, as we have done here, (b) explicitly accounting for the trend in addition to the PDO for a measure of temperature, or (c) defining a new temperature metric in a specified area in the region as is done for the various measures of El Niño (Trenberth, 1997) or more recently as in the NEP index (Johnstone & Mantua, 2014). Interestingly, the NEP was first published just before the recent period of MHWs, and the value of the approach championed in Johnstone and Mantua (2014) has only increased. The wide-ranging effects of the recent period of MHWs are likely to be seen in continuing studies of the eastern North Pacific.

• thunderbolt
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[snowman19]

On 8/1/2024 at 12:08 AM, Stormchaserchuck1 said:

It's interesting that the roll-forwards for warm CONUS Dec - June, and Dec - July, had August as a break month along with December.. This beats even CPC, who was very bullish on much above average temperatures a short time ago. Something to consider.. the roll forwards were very warm every month through March 2025, with Dec and August being only neutral. August looks like it will fit that pattern with a -EPO developing for some of the time. Doesn't mean Sept-Oct will be cool. 

Looking at the ensembles for the next couple of weeks, as of now, your find is pretty uncanny. Aug appears that it will be a break month from the heat. If this continues to follow the script, we see the break this month, then Sept-Nov go way above average, Dec is “neutral”, then Jan-Mar go way above average again….

[mitchnick]

5 hours ago, snowman19 said:

Looking at the ensembles for the next couple of weeks, as of now, your find is pretty uncanny. Aug appears that it will be a break month from the heat. If this continues to follow the script, we see the break this month, then Sept-Nov go way above average, Dec is “neutral”, then Jan-Mar go way above average again….

D@mn you Chuck...d@mn you!

 

 

 

 

 

[PhiEaglesfan712]

7 hours ago, snowman19 said:

Looking at the ensembles for the next couple of weeks, as of now, your find is pretty uncanny. Aug appears that it will be a break month from the heat. If this continues to follow the script, we see the break this month, then Sept-Nov go way above average, Dec is “neutral”, then Jan-Mar go way above average again….

At PHL, 1998-99 stayed warm throughout all of August-February, and didn't have a below average temperature month until March. April and May were near normal.

2007-08 had a very warm August-October, then went below average in November. December was near normal, and we didn't have another below average month until May.

My prediction:

August-October: Well above average

November-December: Near average

January-February: Above average

March-May: Near average

[Stormchaserchuck1]

11 hours ago, snowman19 said:

Looking at the ensembles for the next couple of weeks, as of now, your find is pretty uncanny. Aug appears that it will be a break month from the heat. If this continues to follow the script, we see the break this month, then Sept-Nov go way above average, Dec is “neutral”, then Jan-Mar go way above average again….

Yeah it's pretty high up there on the probability of happening. Here is the final Dec - July map:

So the analogs fit.. I think it was 25 of the 30 that continued the same direction very consistently through the following March (out of 75).  

The central-ENSO subsurface is still posting -6c readings, meaning that water temps there are 12c vs what we saw this time a year ago of 21-22c! There is a -PNA effect in the N. Pacific pattern with those cold subsurface waters..

30mb QBO came in +12.53 for August.. so that is heading toward another strong phase in the Fall and Winter... that is my hesitation on a cold Dec, I think -QBO and La Nina favors cold Decembers but not +qbo. The stronger/faster Polar Vortex at 10mb, has a pretty direct effect to the surface around the Winter solstice. Also, we set some precedents in Dec 2021 when the -PNA hit 600dm. That longer term -PNA phase that is still progressing during that month. 

Because of above normal precip probability, I still like the Great Lakes and interior NE for snow, but now way down here.. -PNA/+NAO is the worst pattern probably besides +EPO. If those storms cut up through the Ohio Valley like I think, we could see a lot of days in the 60s. Of course, there is still the wild card/potential variable that the EPO flips to negative.. I'd give the chance of that happening for the Winter at 15% (13-14 analog) and 20% of a less extreme version of 13-14, which is actually high considering the alternative. I don't think that we'll have another +WPO Winter (5 of the last 6 Winters have been +WPO).  

[Typhoon Tip]

24 minutes ago, Stormchaserchuck1 said:

Yeah it's pretty high up there on the probability of happening. Here is the final Dec - July map:

So the analogs fit.. I think it was 25 of the 30 that continued the same direction very consistently through the following March. 

The central-ENSO subsurface is still posting -6c readings, meaning that water temps there are 12c vs what we saw this time a year ago of 21-22c! There is a -PNA effect in the N. Pacific pattern with those cold subsurface waters. 

30mb QBO came in +12.53 for August.. so that is heading toward another strong phase in the Fall and Winter... that is my hesitation on a cold Dec, I think -QBO and La Nina favors cold Decembers but not +qbo. The stronger/faster Polar Vortex at 10mb, has a pretty direct effect to the surface around the Winter solstice. Also, we set some precedents in Dec 2021 when the -PNA hit 600dm. That is a longer term -PNA phase that is still progressing during that month. 

Because of above normal precip probability, I still like the Great Lakes and interior NE for snow, but now way down here.. -PNA/+NAO is the worst pattern probably besides +EPO. If those storms cut up through the Ohio Valley like I think, we could see a lot of days in the 60s. Of course, there is still the wild card/potential variable that the EPO flips to negative.. I'd give the chance of that happening for the Winter at 15-20% (13-14 analog), with a better chance that it's a less extreme version, but I don't think that we'll have another +WPO Winter. 

I know what's your getting at and don't disagree at a granular level but there are ways in which -PNA/+NAO becomes a problem from the Great Lakes to the upper mid Atlantic and New E regions.   

The simplest way to describe that model is an episodic retrograde of a NW-SE Canadian deep layer conveyor, one that sets up around a big eastern Canadian SPV, which becomes a positive NAO derivative.   But importantly, that sets stage with presage cold loading, prior to RNA sending impulses E ... Storms are flat wave over-runners.  

+EPO ... yeah, that's a tougher sell.

[Stormchaserchuck1]

6 minutes ago, Typhoon Tip said:

I know what's your getting at and don't disagree at a granular level but there are ways in which -PNA/+NAO becomes a problem from the Great Lakes to the upper mid Atlantic and New E regions.   

The simplest way to describe that model is an episodic retrograde of a NW-SE Canadian deep layer conveyor, one that sets up around a big eastern Canadian SPV, which becomes a positive NAO derivative.   But importantly, that sets stage with presage cold loading, prior to RNA sending impulses E ... Storms are flat wave over-runners.  

+EPO ... yeah, that's a tough sell

My thing with a +NAO is, it has been connecting with a N. Pacific ridge in the northern latitudes, more since 2013 and even more since 2019. If that RNA ridge expands over Alaska, you can get some good precip combos in the interior NE as storms run inland (+nao) and hit some pretty strong temp gradients (-epo). 21-22 is one example of the N. Pacific ridge extending north. 

[raindancewx]

May-July looks a bit like a blend of 1999, 2020, 2022 globally at 500 mb.

[snowman19]

2 hours ago, Typhoon Tip said:

I know what's your getting at and don't disagree at a granular level but there are ways in which -PNA/+NAO becomes a problem from the Great Lakes to the upper mid Atlantic and New E regions.   

The simplest way to describe that model is an episodic retrograde of a NW-SE Canadian deep layer conveyor, one that sets up around a big eastern Canadian SPV, which becomes a positive NAO derivative.   But importantly, that sets stage with presage cold loading, prior to RNA sending impulses E ... Storms are flat wave over-runners.  

+EPO ... yeah, that's a tougher sell.

Another thing we’ve been seeing a lot of is the SE ridge/WAR verifying much stronger as we get closer in time thanks to the ++AMO. It has been a common theme for several years now and looks to continue

[snowman19]

4 hours ago, Stormchaserchuck1 said:

Yeah it's pretty high up there on the probability of happening. Here is the final Dec - July map:

So the analogs fit.. I think it was 25 of the 30 that continued the same direction very consistently through the following March (out of 75).  

The central-ENSO subsurface is still posting -6c readings, meaning that water temps there are 12c vs what we saw this time a year ago of 21-22c! There is a -PNA effect in the N. Pacific pattern with those cold subsurface waters..

30mb QBO came in +12.53 for August.. so that is heading toward another strong phase in the Fall and Winter... that is my hesitation on a cold Dec, I think -QBO and La Nina favors cold Decembers but not +qbo. The stronger/faster Polar Vortex at 10mb, has a pretty direct effect to the surface around the Winter solstice. Also, we set some precedents in Dec 2021 when the -PNA hit 600dm. That longer term -PNA phase that is still progressing during that month. 

Because of above normal precip probability, I still like the Great Lakes and interior NE for snow, but now way down here.. -PNA/+NAO is the worst pattern probably besides +EPO. If those storms cut up through the Ohio Valley like I think, we could see a lot of days in the 60s. Of course, there is still the wild card/potential variable that the EPO flips to negative.. I'd give the chance of that happening for the Winter at 15% (13-14 analog) and 20% of a less extreme version of 13-14, which is actually high considering the alternative. I don't think that we'll have another +WPO Winter (5 of the last 6 Winters have been +WPO).  

I didn’t look at the new updated QBO data, I know it just went positive in June, I think you mean July’s number is already up to +12.53, that’s indicative that we are going to have a strong +QBO come December and beyond, so you’re right, that would not be a good sign for a cold December 

[Stormchaserchuck1]

14 minutes ago, snowman19 said:

I didn’t look at the new updated QBO data, I know it just went positive in June, I think you mean July’s number is already up to +12.53, that’s indicative that we are going to have a strong +QBO come December and beyond, so you’re right, that would not be a good sign for a cold December 

Yeah the July number.. I think that means it peaks at >+20 in the next few months. QBO phases aren't always as strong as that.. This makes the ENSO state more sensitive, as a Stronger La Nina will connect in the stratosphere with -10mb conditions in the cold season, likely leading to a +AO. Having a La Nina/+QBO or El Nino/-QBO is about 75% for 10mb anomaly Nov-Mar, which is a pretty high correlation. Having a stronger QBO tightens that up a bit. but a weak La Nina or the subsurface moderating could weaken the signal

[michsnowfreak]

5 hours ago, Stormchaserchuck1 said:

Yeah it's pretty high up there on the probability of happening. Here is the final Dec - July map:

So the analogs fit.. I think it was 25 of the 30 that continued the same direction very consistently through the following March (out of 75).  

The central-ENSO subsurface is still posting -6c readings, meaning that water temps there are 12c vs what we saw this time a year ago of 21-22c! There is a -PNA effect in the N. Pacific pattern with those cold subsurface waters..

30mb QBO came in +12.53 for August.. so that is heading toward another strong phase in the Fall and Winter... that is my hesitation on a cold Dec, I think -QBO and La Nina favors cold Decembers but not +qbo. The stronger/faster Polar Vortex at 10mb, has a pretty direct effect to the surface around the Winter solstice. Also, we set some precedents in Dec 2021 when the -PNA hit 600dm. That longer term -PNA phase that is still progressing during that month. 

Because of above normal precip probability, I still like the Great Lakes and interior NE for snow, but now way down here.. -PNA/+NAO is the worst pattern probably besides +EPO. If those storms cut up through the Ohio Valley like I think, we could see a lot of days in the 60s. Of course, there is still the wild card/potential variable that the EPO flips to negative.. I'd give the chance of that happening for the Winter at 15% (13-14 analog) and 20% of a less extreme version of 13-14, which is actually high considering the alternative. I don't think that we'll have another +WPO Winter (5 of the last 6 Winters have been +WPO).  

Another thing I'm liking in the Great Lakes is that unlike last winter, there looks to be a lot of cold in Canada.

[Stormchaserchuck1]

2 hours ago, michsnowfreak said:

Another thing I'm liking in the Great Lakes is that unlike last winter, there looks to be a lot of cold in Canada.

Wonder if you've seen the CPC's DJF forecast. Looks pretty good for you. 

[bluewave]

July 2024 has just set the new July all-time monthly +PNA record at +2.60. Very strong +PNA patterns began to become a feature with La Ninas in July starting in 1988. So nearly all the top 10 strongest +PNA patterns in July have been during La Ninas. It only took 2 years to beat the previous record set in. 2022. So we can use it as a marker of how strong the La Niña 500 mb pattern has already become after the very strong El Niño last winter.

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

https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

La Nina July +PNA and JJA…..RONI

2024….+2.60…?…………….1st place July +PNA

2022…..+2.54….-0.82…….2nd place July +PNA

2020…..+1.73…..-0.73

2017……+1.86…..-0.16

2007……+2.21….-0.54

1998……+2.24…..-1.07

1988……+2.16…..-1.49

[mitchnick]

5 hours ago, Stormchaserchuck1 said:

Wonder if you've seen the CPC's DJF forecast. Looks pretty good for you. 

Very CFS-ish, especially the wet GL/Ohio Valley. 

[40/70 Benchmark]

Def. grain of salt after reading this site last season and then seeing how the winter evolved....but does lend creedence to my idea that the winter shouldn't be wall-to-wall ++AO/NAO....

https://www.severe-weather.eu/long-range-2/south-pole-stratospheric-warming-winter-2024-2025-influence-forecast-united-states-canada-europe-fa/

Main points:

1. A strong stratospheric warming event is ongoing over the South Pole. It will disrupt the southern polar vortex and help to create and sustain high-pressure anomalies on the surface.
2. The south pole pressure forecast for August-October shows a prolonged period of high-pressure anomalies, creating a negative circulation pattern.
3. Past data and studies show that prolonged high-pressure anomalies over the South Pole in the August-Oct period can influence the weather over the Northern Hemisphere in the following weeks/months.
4. The most likely cause of the weather impacts is the stratospheric connection between the northern and southern polar vortex that helps to transfer the atmospheric dynamics.
5. The prevalent signal in the data shows that strong high-pressure anomalies over the South Pole in the August-Oct period correspond to lower pressure anomalies over the United States and Canada in the Winter season. The data also shows colder-than-normal temperatures over much of the central and eastern parts of the United States.
6. Over Europe, the prevailing signal is a high-pressure anomaly and warmer temperatures during the Winter season.
7. The main final point: These signals and connections are not a fixed rule, as the signal is weak enough to indicate it is not a main (large) driving force of the Winter weather patterns. But it is still visible and does show some form of a role in the overall large-scale atmospheric circulation.

[40/70 Benchmark]

1 hour ago, bluewave said:

July 2024 has just set the new July all-time monthly +PNA record at +2.60. Very strong +PNA patterns began to become a feature with La Ninas in July starting in 1988. So nearly all the top 10 strongest +PNA patterns in July have been during La Ninas. It only took 2 years to beat the previous record set in. 2022. So we can use it as a marker of how strong the La Niña 500 mb pattern has already become after the very strong El Niño last winter.

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

https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

La Nina July +PNA and JJA…..RONI

2024….+2.60…?…………….1st place July +PNA

2022…..+2.54….-0.82…….2nd place July +PNA

2020…..+1.73…..-0.73

2017……+1.86…..-0.16

2007……+2.21….-0.54

1998……+2.24…..-1.07

1988……+2.16…..-1.49

Makes sense to me....ONI is often rubbish in this new world.

[40/70 Benchmark]

10 hours ago, snowman19 said:

I didn’t look at the new updated QBO data, I know it just went positive in June, I think you mean July’s number is already up to +12.53, that’s indicative that we are going to have a strong +QBO come December and beyond, so you’re right, that would not be a good sign for a cold December 

I haven't seen anyone suggest a cold December.....what I have seen is the suggestion that it will be the one month featuring temps relatively close to normal during a very mild winter.

[40/70 Benchmark]

12 hours ago, raindancewx said:

May-July looks a bit like a blend of 1999, 2020, 2022 globally at 500 mb.

I like all of those analog years.

[snowman19]

1 hour ago, 40/70 Benchmark said:

Def. grain of salt after reading this site last season and then seeing how the winter evolved....but does lend creedence to my idea that the winter shouldn't be wall-to-wall ++AO/NAO....
https://www.severe-weather.eu/long-range-2/south-pole-stratospheric-warming-winter-2024-2025-influence-forecast-united-states-canada-europe-fa/
Main points:

1. A strong stratospheric warming event is ongoing over the South Pole. It will disrupt the southern polar vortex and help to create and sustain high-pressure anomalies on the surface.
2. The south pole pressure forecast for August-October shows a prolonged period of high-pressure anomalies, creating a negative circulation pattern.
3. Past data and studies show that prolonged high-pressure anomalies over the South Pole in the August-Oct period can influence the weather over the Northern Hemisphere in the following weeks/months.
4. The most likely cause of the weather impacts is the stratospheric connection between the northern and southern polar vortex that helps to transfer the atmospheric dynamics.
5. The prevalent signal in the data shows that strong high-pressure anomalies over the South Pole in the August-Oct period correspond to lower pressure anomalies over the United States and Canada in the Winter season. The data also shows colder-than-normal temperatures over much of the central and eastern parts of the United States.
6. Over Europe, the prevailing signal is a high-pressure anomaly and warmer temperatures during the Winter season.
7. The main final point: These signals and connections are not a fixed rule, as the signal is weak enough to indicate it is not a main (large) driving force of the Winter weather patterns. But it is still visible and does show some form of a role in the overall large-scale atmospheric circulation.

Was looking at that last week. We saw the same thing in July of 2011, 2007, 2001, 1995, 1992, 1991 and 1980. Not sure about 1980 but I think the others did have some AO disruption. 95 obviously did

 

 

 

 

[40/70 Benchmark]

41 minutes ago, snowman19 said:

Was looking at that last week. We saw the same thing in July of 2011, 2007, 2001, 1995, 1992, 1991 and 1980. Not sure about 1980 but I think the others did have some AO disruption 

 

 

 

 

1991, 1992 and 2011 didn't, although the former two were directly following Pinatubo, so bit of an asterisk there.

Obviously the winter is very likely to average a +NAO and probably AO, but I think what this means is we may see at least one month with decent blocking, which jives with my early inclination from looking at analogs.

[snowman19]

2 hours ago, 40/70 Benchmark said:

I haven't seen anyone suggest a cold December.....what I have seen is the suggestion that it will be the one month featuring temps relatively close to normal during a very mild winter.

I never said anyone was, just responding to Chuck’s point about the QBO rise from June to July and December, nothing more. I suspect we see a strong +QBO in the next several months given that July is already up to over +12 and it just turned positive in June. Whether it’s a big factor in the grand scheme of things, I don’t know