2024-2025 La Nina

[Stormchaserchuck1]

Finally the June map on Climate Divison data updated

Dec-Jun 2023-4

This might be the warmest Dec-Jun on record for the CONUS. 

July is very above average month. Besides the heat that is ongoing now in the East and West, here is the forecast for the end of the month:

But it hasn't been an organic warm period, we've had a +EPO/+NAO in the upper latitudes, which matches analogs of the past, and that is usually the best way we get country-wide heat. 

Here are 30 analogs that I came up with for Dec-July:

The following Winter season (Dec-Feb): (scale is the same lol.. one is hand picked, the other is +6-14 months)

[snowman19]

6 hours ago, Terpeast said:

Climate change.

And no, I'm not being flippant. It's easy to see that if the jet stream runs further north, then everywhere underneath and south of it will be above normal

It’s scary to think how warm the upcoming winter for the CONUS and even parts of Canada would be with a well poleward displaced jet (in combination with AGW) like the Euro is suggesting

[40/70 Benchmark]

6 hours ago, Stormchaserchuck1 said:

Finally the June map on Climate Divison data updated

Dec-Jun 2023-4

This might be the warmest Dec-Jun on record for the CONUS. 

July is very above average month. Besides the heat that is ongoing now in the East and West, here is the forecast for the end of the month:

But it hasn't been an organic warm period, we've had a +EPO/+NAO in the upper latitudes, which matches analogs of the past, and that is usually the best way we get country-wide heat. 

Here are 30 analogs that I came up with for Dec-July:

The following Winter season (Dec-Feb): (scale is the same lol.. one is hand picked, the other is +6-14 months)

I don't think the warmth will be centered in the N plains again next season. I can buy the warmth, but don't necessari;ly agree with the orientation of it.

[40/70 Benchmark]

8 hours ago, Terpeast said:

Yeah those clippers have been replaced by GL lows that always seem to interfere with the genesis of cold highs at the most inopportune times. 

It’s almost as if we need a strong PV to squeeze as far south as Ontario just to get those lows far enough south for DC to snow (like it did twice this January)

Exactly the scenario that could save the northeast in an otherwise awful seasonal pattern...pretty much what happened on 2007-2008.

[40/70 Benchmark]

13 hours ago, George001 said:

I disagree, the 2022-2023 temp profile is not conducive to snow outside of NNE and elevations. The reason I am more optimistic about this winter is the shift in guidance to a later developing Nina. While later developing Nina doesn’t inherently mean better winter for the east, the way this specific event is developing right now (from east to west), the earlier the Nina develops, I would think the earlier in the winter it would shift west. This gives me hope that the Nina will be east based or at least east tilted throughout the first half of winter. 

I think December would be decent for once...

[40/70 Benchmark]

Fell free to beat me senseless with a pillow full of s, but here is a composite of the updated CSU ACE forecast analog seasons...minus 2020, which isn't included on the older data set.

Here is 2020:

 

 

 

 

 

I think a 2020 like season is a reasonable hope for this season.

[snowman19]

37 minutes ago, 40/70 Benchmark said:

Fell free to beat me senseless with a pillow full of s, but here is a composite of the updated CSU ACE forecast analog seasons...minus 2020, which isn't included on the older data set.

Here is 2020:

 

 

 

 

 

I think a 2020 like season is a reasonable hope for this season.

The CSU high ACE forecast is pretty much the only thing that looks good right now, unless there are very drastic changes in the next 4 months

[40/70 Benchmark]

28 minutes ago, snowman19 said:

The CSU high ACE forecast is pretty much the only thing that looks good right now, unless there are very drastic changes in the next 4 months

Yep.......2020 looks like a @bluewaveCC adjusted version of the older high ACE analog seasons. I think a year like that is doable, as 2020 was already high on my list.

[snowman19]

9 minutes ago, 40/70 Benchmark said:

Yep.......2020 looks like a @bluewaveCC adjusted version of the older high ACE analog seasons. I think a year like that is doable, as 2020 was already high on my list.

Pretty much agree. Pray that high ACE forecast works out, because if that’s a fail, I don’t know we avoid an all out disaster outside of interior northern New England 

[bluewave]

1 hour ago, 40/70 Benchmark said:

Yep.......2020 looks like a @bluewaveCC adjusted version of the older high ACE analog seasons. I think a year like that is doable, as 2020 was already high on my list.

We would need a mismatch similar to DJF 20-21 and Jan 22 to see some improvement over the last 2 winters.

https://www.climate.gov/news-features/blogs/enso/did-northern-hemisphere-get-memo-years-la-niña

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JD035546

 

Was the mismatch that we saw in December-January really that unusual?  We know from previous blog posts (like this one) that the atmosphere varies quite a bit from one La Niña to the next, and the atmosphere never fully resembles the average of all events. To address this question, I evaluated the similarity between the individual December-January 500 hPa maps and the average La Niña pattern (for the 13 moderate-to-strong La Niña episodes). For this calculation, I use the pattern correlation, a metric that summarizes the similarity in a single number: a value of 1 means perfect match, 0 means complete mismatch, and -1 means mirror opposites (3).

Pattern correlations between the individual La Niña and average La Niña December – January 500 hPa geopotential height anomalies north of 15°N for the 13 strongest La Niña episodes since 1950. Positive values indicate at least some degree of pattern matching, with 1 indicating a perfect match, and negative values indicate a mismatch between the two patterns. NOAA Climate.gov figure with NCEP/NCAR Reanalysis data obtained from the NOAA Physical Sciences Laboratory.

The pattern correlations are usually substantially positive for moderate-to-strong La Niñas, which indicates that most events share some basic similarity with the average La Niña pattern. This confirms that La Niña is a reliable source of predictability outside of the tropics (and a big reason that we have an ENSO Blog!). However, the pattern correlation for the December 2020 – January of 2021 is the lowest of the 13 events and is actually slightly negative. That means you can argue that the Northern Hemisphere atmosphere looked a little more like El Niño than La Niña!

 

[40/70 Benchmark]

34 minutes ago, bluewave said:

We would need a mismatch similar to DJF 20-21 and Jan 22 to see some improvement over the last 2 winters.

https://www.climate.gov/news-features/blogs/enso/did-northern-hemisphere-get-memo-years-la-niña

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JD035546

 

Was the mismatch that we saw in December-January really that unusual?  We know from previous blog posts (like this one) that the atmosphere varies quite a bit from one La Niña to the next, and the atmosphere never fully resembles the average of all events. To address this question, I evaluated the similarity between the individual December-January 500 hPa maps and the average La Niña pattern (for the 13 moderate-to-strong La Niña episodes). For this calculation, I use the pattern correlation, a metric that summarizes the similarity in a single number: a value of 1 means perfect match, 0 means complete mismatch, and -1 means mirror opposites (3).

Pattern correlations between the individual La Niña and average La Niña December – January 500 hPa geopotential height anomalies north of 15°N for the 13 strongest La Niña episodes since 1950. Positive values indicate at least some degree of pattern matching, with 1 indicating a perfect match, and negative values indicate a mismatch between the two patterns. NOAA Climate.gov figure with NCEP/NCAR Reanalysis data obtained from the NOAA Physical Sciences Laboratory.

The pattern correlations are usually substantially positive for moderate-to-strong La Niñas, which indicates that most events share some basic similarity with the average La Niña pattern. This confirms that La Niña is a reliable source of predictability outside of the tropics (and a big reason that we have an ENSO Blog!). However, the pattern correlation for the December 2020 – January of 2021 is the lowest of the 13 events and is actually slightly negative. That means you can argue that the Northern Hemisphere atmosphere looked a little more like El Niño than La Niña!

 

Well, perhaps injecting an exceedingly anamalous level of tropical energy into the mid and higher latitudes wll help facilitate such a mismatch, since it very well may have in the past.

[bluewave]

58 minutes ago, 40/70 Benchmark said:

Well, perhaps injecting an exceedingly anamalous level of tropical energy into the mid and higher latitudes wll help facilitate such a mismatch, since it very well may have in the past.

The 20-21 mismatch was as if the RONI was so strong in the fall that the MJO 5 peaked  in October and it was weak enough in December for other factors to mute the La Niña background state. We saw this during the stronger La Ninas in 10-11 and 17-18. The weaker La Nina’s like 11-12, 16-17, and 22-23 had weaker MJO 5 activity in October which got stronger during the winter. So an inverse MJO relationship during La Ninas between the fall and winter. 
 

RONI….OND 2020  -1.52 

 

[GaWx]

5 hours ago, 40/70 Benchmark said:

Fell free to beat me senseless with a pillow full of s, but here is a composite of the updated CSU ACE forecast analog seasons...minus 2020, which isn't included on the older data set.

Here is 2020:

 

 

 

 

 

I think a 2020 like season is a reasonable hope for this season.

 La Niña after ACE 200+: 5 winters E US

-1893-4: Dec and Jan NN; Feb BN NE, NN SE

-1933-4: Dec BN NE, AN SE; Jan NN; Feb BN 

-1995-6: Dec, Jan, Feb BN

-2005-6: Dec BN; Jan AN; Feb NN NE, BN SE

-2017-8: Dec BN NE, NN SE; Jan BN; Feb AN

 

By region:

1) NE:

Dec BN 4 of 5; NN 1 of 5; AN 0 of 5

Jan BN 2 of 5; NN 2 of 5; AN 1 of 5

Feb BN 3 of 5; NN 1 of 5; AN 1 of 5

 

2) SE: 

Dec BN 2 of 5; NN 2 of 5; AN 1 of 5

Jan BN 2 of 5; NN 2 of 5; AN 1 of 5

Feb BN 3 of 5; NN 1 of 5; AN 1 of 5

 

Summary of results for these 5 winters

NE: BN strongly prevailed in Dec and moderately prevailed in Feb; Jan all over map

SE: BN moderately prevailed in Feb; DJ all over map

 

*Caution advised due to small sample size as there’s possibility this was due to randomness. This is not at all a forecast for 2024-5 or any other Nina winter following 200+ ACE.*

 

[snowman19]

3 minutes ago, GaWx said:

 La Niña after ACE 200+: 5 winters E US

-1893-4: Dec and Jan NN; Feb BN NE, NN SE

-1933-4: Dec BN NE, AN SE; Jan NN; Feb BN 

-1995-6: Dec, Jan, Feb BN

-2005-6: Dec BN; Jan AN; Feb NN NE, BN SE

-2017-8: Dec BN NE, NN SE; Jan BN; Feb AN

 

By region:

1) NE:

Dec BN 4 of 5; NN 1 of 5; AN 0 of 5

Jan BN 2 of 5; NN 2 of 5; AN 1 of 5

Feb BN 3 of 5; NN 1 of 5; AN 1 of 5

 

2) SE: 

Dec BN 2 of 5; NN 2 of 5; AN 1 of 5

Jan BN 2 of 5; NN 2 of 5; AN 1 of 5

Feb BN 3 of 5; NN 1 of 5; AN 1 of 5

 

Summary

NE: BN strongly favored in Dec and moderately favored in Feb; Jan a tossup

SE: BN moderately favored in Feb; DJ tossups

 

*Caution advised due to small sample size*

 

Just using 95-96 as an example, yes, it had the record high Atlantic ACE, but did that directly lead to the massive -NAO/-AO blocking that winter or was it the low solar/geo mag, -QBO, +PDO, weak east-based Niña that would have lead to it regardless, even if it wasn’t high ACE? 

[GaWx]

2 minutes ago, snowman19 said:

Just using 95-96 as an example, yes, it had the record high Atlantic ACE, but did that directly lead to the massive -NAO/-AO blocking that winter or was it the low solar/geo mag, -QBO, +PDO, weak east-based Niña that would have lead to it regardless, even if it wasn’t high ACE? 

That’s why I said this:

*Caution advised due to small sample size as there’s possibility this was due to randomness*

[brooklynwx99]

5 hours ago, 40/70 Benchmark said:

Fell free to beat me senseless with a pillow full of s, but here is a composite of the updated CSU ACE forecast analog seasons...minus 2020, which isn't included on the older data set.

Here is 2020:

 

 

 

 

 

I think a 2020 like season is a reasonable hope for this season.

this has 19-20, not 20-21... summer of 2020 was one of those high ACE years

[Stormchaserchuck1]

I don't see why Beryl ACE 36 is going to effect the Winter.. It tracked very far south in July. The correlation is turning up N. Atlantic waters late Summer/early Fall, but even that is a very, very small thing. Usually it's the larger pattern producing X effects (cyclones) that has the weight/correlation, but +AMO/-PDO/La Nina, which is why it's likely going to be a high ACE year, is not really a cold Winter composite.  Humans can be a variable too though, I guess. I noticed changes in the weather pattern when Beryl was hitting..

[snowman19]

17 minutes ago, Stormchaserchuck1 said:

I don't see why Beryl ACE 36 is going to effect the Winter.. It tracked very far south in July. The correlation is turning up N. Atlantic waters late Summer/early Fall, but even that is a very, very small thing. Usually it's the larger pattern producing X effects (cyclones) that has the weight/correlation, but +AMO/-PDO/La Nina, which is why it's likely going to be a high ACE year, is not really a cold Winter composite.  Humans can be a variable too though, I guess. I noticed changes in the weather pattern when Beryl was hitting..

That’s what I meant to ask Ray before but it slipped my mind. I vaguely remember the correlation being high ACE with recurves releasing latent and sensible heat energy into the tropopause of the North Atlantic. Not sure if it applied to East-West tracking tropical systems too, I honestly didn’t read into the research I had seen on it years ago, but I do remember that recurves were mentioned

[Stormchaserchuck1]

3 minutes ago, snowman19 said:

That’s what I meant to ask Ray before but it slipped my mind. I vaguely remember the correlation being high ACE with recurves releasing latent and sensible heat energy into the tropopause of the North Atlantic. Not sure if it applied to East-West tracking tropical systems too, I honestly didn’t read into the research I had seen on it years ago, but I do remember that recurves were mentioned

I remember reading something about recurves being the biggest variable, they were connecting it with the NAO. I think you need a really neutral climate for such a thing to occur. 

[mitchnick]

I was looking at the numbers behind the attached pic representing equatorial temp anomalies surface to 300 meters down. I found the actual numbers used to generate that chart at the link below. It only goes back to 1979, so it's without the 72/73 Super Niño.  But if you look at all the springs/early summers after strong and super Niños since 79', in years when a Niña followed, temps from the surface down became much cooler than this year. In fact, this year bottomed in April, held steady in May, and started warming again in June. No other post Niño  spring/early summer did that. I know we don't have too many years to consider (I looked at 82/83, 91/92, 97/98, 15/16, & 23/24.) My point is, this year is unlike any other post strong/super Niño spring since 1979. So it just makes me think that for Enso to reach anything colder than a weak Niña will be tough, if at all. And even assuming a moderate to strong background Niña state of the atmosphere, what would the warmer waters mean to an eastern conus winter? Dunno and I'm too lazy to look!!!

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

P.s. Moderate Niños of 86/87, 94/95, 02/03, & 09/10 that were followed by a Niña also had larger temp drops by the following June than this year.

[michsnowfreak]

8 hours ago, 40/70 Benchmark said:

Fell free to beat me senseless with a pillow full of s, but here is a composite of the updated CSU ACE forecast analog seasons...minus 2020, which isn't included on the older data set.

Here is 2020:

 

 

 

 

 

I think a 2020 like season is a reasonable hope for this season.

So to clarify, that would be winters: 1885-86, 1925-26, 1932-33. 1994-95, 2004-05, 2009-10, & 2019-20?

[PhiEaglesfan712]

1 hour ago, mitchnick said:

I was looking at the numbers behind the attached pic representing equatorial temp anomalies surface to 300 meters down. I found the actual numbers used to generate that chart at the link below. It only goes back to 1979, so it's without the 72/73 Super Niño.  But if you look at all the springs/early summers after strong and super Niños since 79', in years when a Niña followed, temps from the surface down became much cooler than this year. In fact, this year bottomed in April, held steady in May, and started warming again in June. No other post Niño  spring/early summer did that. I know we don't have too many years to consider (I looked at 82/83, 91/92, 97/98, 15/16, & 23/24.) My point is, this year is unlike any other post strong/super Niño spring since 1979. So it just makes me think that for Enso to reach anything colder than a weak Niña will be tough, if at all. And even assuming a moderate to strong background Niña state of the atmosphere, what would the warmer waters mean to an eastern conus winter? Dunno and I'm too lazy to look!!!

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

P.s. Moderate Niños of 86/87, 94/95, 02/03, & 09/10 that were followed by a Niña also had larger temp drops by the following June than this year.

I wouldn't put 86-87 on that list, unless you mean that 88 was the transition year. There was no cooling in June 87, as the el nino continued into 87-88, before dissipating in early 88 and producing a historically strong la nina in 88-89. That said, I'd consider the 86-88 event to be strong, since we reached over +1.5 on both the ONI and RONI. Same with 09-10, which also produced a strong la nina the following year.

02-03 didn't produce a la nina the following year. 03-04 was ENSO neutral.

91-92 didn't really cool. We didn't even get a la nina in 92-93 or 93-94. I wonder if the eruption of Mount Pinatubo affected this one. That's the only strong el nino event that wasn't followed by a la nina since 72-73.

[GaWx]

1 hour ago, michsnowfreak said:

So to clarify, that would be winters: 1885-86, 1925-26, 1932-33. 1994-95, 2004-05, 2009-10, & 2019-20?

 No, it is one winter after each of these since it is the winter following a high ACE season.

[bluewave]

5 hours ago, snowman19 said:

Just using 95-96 as an example, yes, it had the record high Atlantic ACE, but did that directly lead to the massive -NAO/-AO blocking that winter or was it the low solar/geo mag, -QBO, +PDO, weak east-based Niña that would have lead to it regardless, even if it wasn’t high ACE? 

The 95-96 record winter snowfall in NYC may have been related to the AMO warming which occurred that year. Boston had their snowiest winter in 15 with the brief shift to the +PDO. But the shift only lasted a few years before we entered the record -PDO regime of recent years. The famous 76-77 winter occurred as the PDO was changing from negative to positive. So we seem to get interesting winters around these change points. 

[raindancewx]

The composite above for the ACE seasons is completely wrong. Some of the ESRL sites have winters tied to the final year of the monthly period, others have the winter tied to the start. This is the actual composite of the recent highest ACE years. The idea is much higher than normal pressure over the SW and West. Cold drains into the East.

[Terpeast]

18 minutes ago, raindancewx said:

The composite above for the ACE seasons is completely wrong. Some of the ESRL sites have winters tied to the final year of the monthly period, others have the winter tied to the start. This is the actual composite of the recent highest ACE years. The idea is much higher than normal pressure over the SW and West. Cold drains into the East.

Thanks for posting this. It's worth noting the ridge over the aleutian islands. That major ridge over far northern europe and NW eurasia is also remarkable, and makes sense in the context of ACE.

[michsnowfreak]

4 hours ago, GaWx said:

 No, it is one winter after each of these since it is the winter following a high ACE season.

Thanks for clearing that up. 1886-87, 1926-27, 1933-34, 1995-96, 2005-06, 2010-11, & 2020-21. Not a bad dataset at all!

[PhiEaglesfan712]

4 hours ago, bluewave said:

The 95-96 record winter snowfall in NYC may have been related to the AMO warming which occurred that year. Boston had their snowiest winter in 15 with the brief shift to the +PDO. But the shift only lasted a few years before we entered the record -PDO regime of recent years. The famous 76-77 winter occurred as the PDO was changing from negative to positive. So we seem to get interesting winters around these change points. 

I'd argue that the +PDO in 95-96 was part of the secular +PDO period that started in mid-76 (when the multi-year la nina ended) and ended in mid-98 (when the 97-98 super el nino dissipated). I'd consider 98-99 as a change point winter, when we went from +PDO to -PDO, rather than 95-96. The historically strong la nina of 88-89 was really the only time between 76 and 98 when we had a sustained -PDO (kind of like how the 14-16 el nino is the only time we've seen sustained +PDO since 98). That time was predominated by el ninos, especially the strong events of 82-83, 86-88, 91-92, and 97-98.

[raindancewx]

Dead on match for the high ACE years so far in June (not). I'm sure the season will have active periods but I'm still pretty skeptical of 200+ ACE.

[so_whats_happening]

I would imagine if we even start to see a semblance of an average typhoon season we could start to show a nice cool tongue across the pacific as we get toward fall but there is a lot of work to be done. I do still find it weird we have this dual basin cold equator look that is not typical in El Nino or La Nina years (last year we also had a warm tongue through the Atlantic with a strong/super Nino). I would be curious if there is an ongoing study about this phenomena.