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El Nino 2023-2024


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2 hours ago, 40/70 Benchmark said:

You know, I am honestly toying with the notion of using that relative ONI that Larry referenced last week....essentially ONI -.4....ie 1.5 ONI will equate to a 1.1 adjusted ONI and hence that level of forcing on the atmosphere. On the flip end of the spectrum...this past season illustrated how utterly useless the ONI can be with respect to diagnosing winter, as the RONI had to have been much lower than 1.0.

To me, it is a better pathway using the relative approach.  Not to bloviate my own horn, but I've been trying to explain that for a number of years - as ( at minimum ) a partial explanation in why some of these ENSO impact climates, over the past 20 years, have been increasingly less well correlated. 

Question to answer which might help:  

- when the total ENSO state is deduced, is that compared to history, or is it compared to the surrounding ambient planetary state at the time of the computations?

If it is the latter, than the "relativity" is already baked in. If it is former, 'comparing history,' then lets ask the following question:   Does the +1.5 anomaly mean the same thing if the whole planetary system around it is also +1.5?  

Mmm   if that doesn't shutter the assumption at least a little ...folks need to consider a new hobby.  Even if the ENSO is on a 'sliding scale' - it still needs to be studied as to whether it's forcing is the same.

Also, a separate gripe:  part of the problem I have with these charts and graphs that are abundant on the free web ... is that they appear to refer to every metric in context that deviates from a given norm as though it is a statistical anomaly.  But in reality, what is conveyed really just refers to a departure from the norm in question. A real statistical anomaly is based upon the standard deviation derivative.  And that matters for this question above... because it logically leads to an important methodology issue which whether folks want to admit this or not ... climate change is changing the "standard model" for heat source vs sink ... and that's like taking Ferrari engine out and replacing it with a F150.  They both run, but they rev and power distribution at different frequencies.

 

 

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3 minutes ago, Typhoon Tip said:

To me, it is a better pathway using the relative approach.  Not to bloviate my own horn, but I've been trying to explain that for a number of years - as ( at minimum ) a partial explanation in why some of these ENSO impact climates, over the past 20 years, have been increasingly less well correlated. 

ENSO has been competing with marine heatwaves in other regions. So the combination of multiple forcing areas yields new patterns. This is especially true with the El Niños due to the record WPAC warm pool imparting more of a MJO 4-6 La Niña influence. Just look at all the incorrect El Niño seasonal forecasts since 12-13. Several La Ninas over this period have featured Nino-like precipitation totals in California in years like 16-17 and 22-23. So we need to take a more comprehensive approach to seasonal forecasting. Pre-2010 analogs haven’t been working out in this newer climate era.

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25 minutes ago, bluewave said:

ENSO has been competing with marine heatwaves in other regions. So the combination of multiple forcing areas yields new patterns. This is especially true with the El Niños due to the record WPAC warm pool imparting more of a MJO 4-6 La Niña influence. Just look at all the incorrect El Niño seasonal forecasts since 12-13. Several La Ninas over this period have featured Nino-like precipitation totals in California in years like 16-17 and 22-23. So we need to take a more comprehensive approach to seasonal forecasting. Pre-2010 analogs haven’t been working out in this newer climate era.

Bingo.

Also, Ray mentions this point and it is a good one.   People likely already know ... but the NP-Lakes-NE mid latitude continent is hugely subjected to the peregrinations of the polar ward index/idiosyncrasies, which are at best ...vaguely correlated ( certainly not directly and if at all, lots of temporal lag) to ENSOs.  The circuitry is perhaps through the QBO ... which almost immediately argues temporal lags ...  what a rabbit hole.  

CPC seasonal long lead outlooks issued Aug - Oct began mentioning this facet above, about the shaky reliance with the ENSO in these boreal latitudes described above... directly citing AO(NAO) some years ago - not sure if they still have that disclaimer recently, but it's always applicable.  

It's like ENSO really seems to on shaky ground in general as the primary background assumption. So the 'more comprehensive' aspect you mentioned... yar, that's agreed -

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I don't think anyone is actually dumb enough to forecast seasonally just based on ENSO. 

I have a seven factor method for seasonal stuff nationally. Then once the general idea is determined, I try to narrow it on the monthly patterns. But that's much harder.

The atmospheric river thing in La Nina is not really new though either. The Great Flood of 1862 in the West was not an El Nino as an example. These are not new patterns.

https://en.wikipedia.org/wiki/Great_Flood_of_1862

Any of this sound familiar?

The Great Flood of 1862 was the largest flood in the recorded history of California, Oregon, and Nevada, inundating the western United States and portions of British Columbia and Mexico. It was preceded by weeks of continuous rains and snows that began in Oregon in November 1861 and continued into January 1862. This was followed by a record amount of rain from January 9–12, and contributed to a flood that extended from the Columbia River southward in western Oregon, and through California to San Diego, and extended as far inland as Idaho in the Washington Territory, Nevada and Utah in the Utah Territory, and Arizona in the western New Mexico Territory. The event dumped an equivalent of 10 feet (3.0 m) of water in California, in the form of rain and snow, over a period of 43 days.[3][4] Immense snowfalls in the mountains of far western North America caused more flooding in Idaho, Arizona, New Mexico, as well as in Baja California and Sonora, Mexico the following spring and summer, as the snow melted.

 

...The weather pattern that caused this flood was not from an El Niño-type event, and from the existing Army and private weather records, it has been determined that the polar jet stream was to the north, as the Pacific Northwest experienced a mild rainy pattern for the first half of December 1861. In 2012, hydrologists and meteorologists concluded that the precipitation was likely caused by a series of atmospheric rivers that hit the Western United States along the entire West Coast, from Oregon to Southern California.[6]

An atmospheric river is a wind-borne, deep layer of water vapor with origins in the tropics, extending from the surface to high altitudes, often above 10,000 feet, and concentrated into a relatively narrow band, typically about 400 to 600 kilometres (250 to 370 mi) wide, usually running ahead of a frontal boundary, or merging into it.[7][8] With the right dynamics in place to provide lift, an atmospheric river can produce astonishing amounts of precipitation, especially if it stalls over an area for any length of time.

...The floods followed a 20-year-long drought.[9] During November, prior to the flooding, Oregon had steady but heavier-than-normal rainfall, with heavier snow in the mountains.[10]: 76–83  Researchers believe the jet stream had slipped south, accompanied by freezing conditions reported at Oregon stations by December 25. Heavy rainfall began falling in California as the longwave trough moved south over the state, remaining there until the end of January 1862, causing precipitation to fall everywhere in the state for nearly 40 days. Eventually, the trough moved even further south, causing snow to fall in the Central Valley and surrounding mountain ranges (15 feet of snow in the Sierra Nevada).[11][12]

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26 minutes ago, raindancewx said:

I don't think anyone is actually dumb enough to forecast seasonally just based on ENSO. 

I have a seven factor method for seasonal stuff nationally. Then once the general idea is determined, I try to narrow it on the monthly patterns. But that's much harder.

The atmospheric river thing in La Nina is not really new though either. The Great Flood of 1862 in the West was not an El Nino as an example. These are not new patterns.

https://en.wikipedia.org/wiki/Great_Flood_of_1862

Any of this sound familiar?

The Great Flood of 1862 was the largest flood in the recorded history of California, Oregon, and Nevada, inundating the western United States and portions of British Columbia and Mexico. It was preceded by weeks of continuous rains and snows that began in Oregon in November 1861 and continued into January 1862. This was followed by a record amount of rain from January 9–12, and contributed to a flood that extended from the Columbia River southward in western Oregon, and through California to San Diego, and extended as far inland as Idaho in the Washington Territory, Nevada and Utah in the Utah Territory, and Arizona in the western New Mexico Territory. The event dumped an equivalent of 10 feet (3.0 m) of water in California, in the form of rain and snow, over a period of 43 days.[3][4] Immense snowfalls in the mountains of far western North America caused more flooding in Idaho, Arizona, New Mexico, as well as in Baja California and Sonora, Mexico the following spring and summer, as the snow melted.

 

...The weather pattern that caused this flood was not from an El Niño-type event, and from the existing Army and private weather records, it has been determined that the polar jet stream was to the north, as the Pacific Northwest experienced a mild rainy pattern for the first half of December 1861. In 2012, hydrologists and meteorologists concluded that the precipitation was likely caused by a series of atmospheric rivers that hit the Western United States along the entire West Coast, from Oregon to Southern California.[6]

An atmospheric river is a wind-borne, deep layer of water vapor with origins in the tropics, extending from the surface to high altitudes, often above 10,000 feet, and concentrated into a relatively narrow band, typically about 400 to 600 kilometres (250 to 370 mi) wide, usually running ahead of a frontal boundary, or merging into it.[7][8] With the right dynamics in place to provide lift, an atmospheric river can produce astonishing amounts of precipitation, especially if it stalls over an area for any length of time.

...The floods followed a 20-year-long drought.[9] During November, prior to the flooding, Oregon had steady but heavier-than-normal rainfall, with heavier snow in the mountains.[10]: 76–83  Researchers believe the jet stream had slipped south, accompanied by freezing conditions reported at Oregon stations by December 25. Heavy rainfall began falling in California as the longwave trough moved south over the state, remaining there until the end of January 1862, causing precipitation to fall everywhere in the state for nearly 40 days. Eventually, the trough moved even further south, causing snow to fall in the Central Valley and surrounding mountain ranges (15 feet of snow in the Sierra Nevada).[11][12]

Thank you for posting this.

We don't pay enough attention to these historical extremes of weather, so we get caught out when they happen again.

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Yes, they were basin-wide with an eastward lean....kind of like what is modeled for this season's el nino.

Agree. Maybe it goes basin-wide? That said, I very highly doubt a Modoki this year, if you look back at all the years that started off this extremely east-based, none of them went to a true Modoki configuration. My guess is that it either stays east-based (most likely) or it goes basin-wide
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21 hours ago, bluewave said:

ENSO has been competing with marine heatwaves in other regions. So the combination of multiple forcing areas yields new patterns. This is especially true with the El Niños due to the record WPAC warm pool imparting more of a MJO 4-6 La Niña influence. Just look at all the incorrect El Niño seasonal forecasts since 12-13. Several La Ninas over this period have featured Nino-like precipitation totals in California in years like 16-17 and 22-23. So we need to take a more comprehensive approach to seasonal forecasting. Pre-2010 analogs haven’t been working out in this newer climate era.

The 2018-2019 to 2019-2020 warm ENSO handed me my as$....those were my worst seasonals....especially the latter.

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19 minutes ago, snowman19 said:


Agree. Maybe it goes basin-wide? That said, I very highly doubt a Modoki this year, if you look back at all the years that started off this extremely east-based, none of them went to a true Modoki configuration. My guess is that it either stays east-based (most likely) or it goes basin-wide

I think basin-wide is the most likely outcome for winter.

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57 minutes ago, 40/70 Benchmark said:

The 2018-2019 to 2019-2020 warm ENSO handed me my as$....those were my worst seasonals....especially the latter.

Yeah, we were getting clues in the fall of 18 that the El Niño wasn’t coupling. Then record IOD in the fall of 19 seems to have drove the record polar vortex and +NAO that winter. So the WPAC warm pool won out in 18-19 and the Indian Ocean in 19-20. 
 


https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

 
First published: 30 July 2020
 
Citations: 26

Funding information: Met Office Hadley Centre Climate Programme funded by BEIS and Defra

 

Abstract

Northern Europe and the UK experienced an exceptionally warm and wet winter in 2019/20, driven by an anomalously positive North Atlantic Oscillation (NAO). This positive NAO was well forecast by several seasonal forecast systems, suggesting that this winter the NAO was highly predictable at seasonal lead times. A very strong positive Indian Ocean dipole (IOD) event was also observed at the start of winter. Here we use composite analysis and model experiments, to show that the IOD was a key driver of the observed positive NAO. Using model experiments that perturb the Indian Ocean initial conditions, two teleconnection pathways of the IOD to the north Atlantic emerge: a tropospheric teleconnection pathway via a Rossby wave train travelling from the Indian Ocean over the Pacific and Atlantic, and a stratospheric teleconnection pathway via the Aleutian region and the stratospheric polar vortex. These pathways are similar to those for the El Niño Southern Oscillation link to the north Atlantic which are already well documented. The anomalies in the north Atlantic jet stream location and strength, and the associated precipitation anomalies over the UK and northern Europe, as simulated by the model IOD experiments, show remarkable agreement with those forecast and observed.

In winter 2019/20, the observed sea surface temperatures in the west/east parts of the Indian Ocean basin were anomalously warm/cold, leading to a positive Indian Ocean Dipole (IOD; Saji et al., 1999; Webster et al., 1999) that was the second strongest recorded since 1972 (Doi et al., 2020).

A knowledge of the teleconnection pathways between the IOD and the North Atlantic gives greater confidence in the seasonal forecast skill they offer. The frequency of positive IOD events has doubled in the 20th century, and their intensity has also increased, with this trend projected to continue (Abram et al., 2020). It is likely, therefore, that such connections will become increasingly important for seasonal forecasting of European winters during the rest of the 21st century.

 

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12 hours ago, raindancewx said:

I don't think anyone is actually dumb enough to forecast seasonally just based on ENSO. 

I have a seven factor method for seasonal stuff nationally. Then once the general idea is determined, I try to narrow it on the monthly patterns. But that's much harder.

The atmospheric river thing in La Nina is not really new though either. The Great Flood of 1862 in the West was not an El Nino as an example. These are not new patterns.

https://en.wikipedia.org/wiki/Great_Flood_of_1862

Any of this sound familiar?

The Great Flood of 1862 was the largest flood in the recorded history of California, Oregon, and Nevada, inundating the western United States and portions of British Columbia and Mexico. It was preceded by weeks of continuous rains and snows that began in Oregon in November 1861 and continued into January 1862. This was followed by a record amount of rain from January 9–12, and contributed to a flood that extended from the Columbia River southward in western Oregon, and through California to San Diego, and extended as far inland as Idaho in the Washington Territory, Nevada and Utah in the Utah Territory, and Arizona in the western New Mexico Territory. The event dumped an equivalent of 10 feet (3.0 m) of water in California, in the form of rain and snow, over a period of 43 days.[3][4] Immense snowfalls in the mountains of far western North America caused more flooding in Idaho, Arizona, New Mexico, as well as in Baja California and Sonora, Mexico the following spring and summer, as the snow melted.

 

...The weather pattern that caused this flood was not from an El Niño-type event, and from the existing Army and private weather records, it has been determined that the polar jet stream was to the north, as the Pacific Northwest experienced a mild rainy pattern for the first half of December 1861. In 2012, hydrologists and meteorologists concluded that the precipitation was likely caused by a series of atmospheric rivers that hit the Western United States along the entire West Coast, from Oregon to Southern California.[6]

An atmospheric river is a wind-borne, deep layer of water vapor with origins in the tropics, extending from the surface to high altitudes, often above 10,000 feet, and concentrated into a relatively narrow band, typically about 400 to 600 kilometres (250 to 370 mi) wide, usually running ahead of a frontal boundary, or merging into it.[7][8] With the right dynamics in place to provide lift, an atmospheric river can produce astonishing amounts of precipitation, especially if it stalls over an area for any length of time.

...The floods followed a 20-year-long drought.[9] During November, prior to the flooding, Oregon had steady but heavier-than-normal rainfall, with heavier snow in the mountains.[10]: 76–83  Researchers believe the jet stream had slipped south, accompanied by freezing conditions reported at Oregon stations by December 25. Heavy rainfall began falling in California as the longwave trough moved south over the state, remaining there until the end of January 1862, causing precipitation to fall everywhere in the state for nearly 40 days. Eventually, the trough moved even further south, causing snow to fall in the Central Valley and surrounding mountain ranges (15 feet of snow in the Sierra Nevada).[11][12]

I'm not sure of everyone's particular contribution in this social media, but for me this speculation was/is not a matter of "...forecast seasonally just based on ENSO

-altho, there are many seasonal outlooks where the methodology conveyed does not signal the author did rely much upon anything else ... That's not uncommon either.

It's a matter of sciencing (asking the question) over the amounts of weighted contribution. 

And also, agreed - there are no 1::1 correlations in atmospheric mode to mode relationships, nor in the events that take place over time during dominate modes of either that affect a region. Obviously river phenomenon can happen in La Nina. But when the entire manifold of different climate pathways, in general, in which ENSO is correlated begin demonstrating increased frequency of occurrences in which the correlations are less represented, that is a suggestion that the system is changing - that's just analytic/academic. That's what is paramount ( at least ) in my recent contribution to this thread.

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Yeah, we were getting clues in the fall of 18 that the El Niño wasn’t coupling. Then record IOD in the fall of 19 seems to have drove the record polar vortex and +NAO that winter. So the WPAC warm pool won out in 18-19 and the Indian Ocean in 19-20. 
 

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

  Steven C. HardimanNick J. DunstoneAdam A. ScaifeDoug M. SmithJeff R. KnightPaul DaviesMartin ClausRichard J. Greatbatch First published: 30 July 2020   https://doi.org/10.1002/asl.1005 Citations: 26 Funding information: Met Office Hadley Centre Climate Programme funded by BEIS and Defra
SECTIONS pdf-icon-169a2eb30e52100e76dfa5f4b66998e6.pngPDF TOOLS  SHARE  

Abstract

Northern Europe and the UK experienced an exceptionally warm and wet winter in 2019/20, driven by an anomalously positive North Atlantic Oscillation (NAO). This positive NAO was well forecast by several seasonal forecast systems, suggesting that this winter the NAO was highly predictable at seasonal lead times. A very strong positive Indian Ocean dipole (IOD) event was also observed at the start of winter. Here we use composite analysis and model experiments, to show that the IOD was a key driver of the observed positive NAO. Using model experiments that perturb the Indian Ocean initial conditions, two teleconnection pathways of the IOD to the north Atlantic emerge: a tropospheric teleconnection pathway via a Rossby wave train travelling from the Indian Ocean over the Pacific and Atlantic, and a stratospheric teleconnection pathway via the Aleutian region and the stratospheric polar vortex. These pathways are similar to those for the El Niño Southern Oscillation link to the north Atlantic which are already well documented. The anomalies in the north Atlantic jet stream location and strength, and the associated precipitation anomalies over the UK and northern Europe, as simulated by the model IOD experiments, show remarkable agreement with those forecast and observed.
In winter 2019/20, the observed sea surface temperatures in the west/east parts of the Indian Ocean basin were anomalously warm/cold, leading to a positive Indian Ocean Dipole (IOD; Saji et al., 1999; Webster et al., 1999) that was the second strongest recorded since 1972 (Doi et al., 2020).
A knowledge of the teleconnection pathways between the IOD and the North Atlantic gives greater confidence in the seasonal forecast skill they offer. The frequency of positive IOD events has doubled in the 20th century, and their intensity has also increased, with this trend projected to continue (Abram et al., 2020). It is likely, therefore, that such connections will become increasingly important for seasonal forecasting of European winters during the rest of the 21st century.
 

The impact of the record +IOD of 19-20 was grossly underestimated. SSTs north of Australia were 90+ at the end of that summer. It totally altered the global heat budget and helped lead to the ridiculously positive NAM and NAO and SPV that winter
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20 minutes ago, snowman19 said:


The impact of the record +IOD of 19-20 was grossly underestimated. SSTs north of Australia were 90+ at the end of that summer. It totally altered the global heat budget and helped lead to the ridiculously positive NAM and NAO and SPV that winter

The winter extremes since the 09-10 have been off the charts. Numerous individual season firsts including changes from year to year. So not an easy period for long range winter forecasts. Record SE Ridge or WAR patterns since December 2015 leading to first run of 8 warmer than average winters in Northeast.

 

09-10….Strongest -NAO -AO winter and all-time seasonal snowfall totals in Midatlantic. One of the strongest purely Modoki El Niño’s on record.

10-11 strongest -AO -NAO for such a strong La Niña and record 33 day snowfall totals around NYC metro.

11-12 very impressive +EPO and winter warmth leading to summer in March pattern.

12-13……Record snowfall rates and totals with Nemo.

13-14……Record NE PAC blocking and warm blob leading to cold and snowy in the East.

14-15 record NE PAC blocking continues combined with record +NAO and record Boston snowfall. Trades staying up result in weak Modoki signature. Several models forecast very strong El Niño early on.

15-16 furthest west based super El Niño. First MJO 4-6 so strong in December super El Niño leading to +13 December. All-time heaviest snowstorm in NYC during January. First below 0° in February since Jan 94.

16-17 unusually snowy on parts of Long Island for such a warm and weak  La Niña. 60° warmth a day before blizzard in February. Have seen this warm to snowy or snowy to warm repeating more frequently.

17-18 great post Christmas to early January winter pattern with the record 950mb benchmark blizzard. Record La Niña shift to warm in February with first winter 80° around NYC in February. Highest 500 mb height on record for cold season in February in Northeast. Record 30” snows on Long Island in March.

18-19 very rare uncoupled El Niño due to record WPAC warm pool.

19-20 near record warmth and +NAO with 2nd strongest IOD

20-21 back to La Niña with unusually strong December +PNA for a -PDO. Also one of our more recent south based -AO blocks makes appearance in December with snowy outcome. Great finish to season in February especially for a La Niña which is usually more front-loaded.

21-22….Strongest January +PNA blocking following  such a record October -PDO dipping below -3.

22-23….First December -AO so south based which was the 2nd overall most negative for month. Lowest December snowfall outcome for such strong -AO. Warmest rest of winter following such strong December blocking.

 

 

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Solid!

1654894132_MidApr-E.O.M23Uwindanom.thumb.gif.4dc5d0f6bc92932189254a525793365b.gif

Models are catching onto the tropical activity around 150E from my post the other day. Gotta say GFS sniffed that out pretty well seems to have a solid handle on some aspects as of right now so it will be interesting to watch the results of this. Nice MJO spike with activity abound in the SW Pacific. 

So it seems as though we can't seem to get a passage of a WWB event past this region, trades are just holding on tight and what seems to be a continuation is 1+2 will warm again via Kelvin wave activity and slowly spread the warmth across the region. Honestly would really like to see the trades relax more and allow a WWB through doesn't have to be that strong throughout just needs to be enough to allow a solid overall weakening and maybe even reversal?

Could see some interesting forecasts if we can see that in June until then we wait. PDO is taking a solid beating, unfortunately NW Canada is on fire big time been getting smoke well aloft for the last week and a half. Starting to see the changes needed to resemble a +PDO look trying to switch things up 7 day change doing its thing.

ct5km_sst-trend-7d_v3.1_global_current Mid MAy 23.png

ssta_animation_30day_large Mid APR- Mid May 23.gif

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19 minutes ago, so_whats_happening said:

Solid!

1654894132_MidApr-E.O.M23Uwindanom.thumb.gif.4dc5d0f6bc92932189254a525793365b.gif

Models are catching onto the tropical activity around 150E from my post the other day. Gotta say GFS sniffed that out pretty well seems to have a solid handle on some aspects as of right now so it will be interesting to watch the results of this. Nice MJO spike with activity abound in the SW Pacific. 

So it seems as though we can't seem to get a passage of a WWB event past this region, trades are just holding on tight and what seems to be a continuation is 1+2 will warm again via Kelvin wave activity and slowly spread the warmth across the region. Honestly would really like to see the trades relax more and allow a WWB through doesn't have to be that strong throughout just needs to be enough to allow a solid overall weakening and maybe even reversal?

Could see some interesting forecasts if we can see that in June until then we wait. PDO is taking a solid beating, unfortunately NW Canada is on fire big time been getting smoke well aloft for the last week and a half. Starting to see the changes needed to resemble a +PDO look trying to switch things up 7 day change doing its thing.

ct5km_sst-trend-7d_v3.1_global_current Mid MAy 23.png

ssta_animation_30day_large Mid APR- Mid May 23.gif

I was going to point out a pdo reversal after cpc’s monday enso report. But you summed it up. 

Selfishly, we want a positive pdo, but it could be disastrous for NW canada.

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39 minutes ago, Terpeast said:

I was going to point out a pdo reversal after cpc’s monday enso report. But you summed it up. 

Selfishly, we want a positive pdo, but it could be disastrous for NW canada.

Yea it is a shame to see but for sure it would at least throw a potential our way come winter, if it holds.

Definitely would be nice to shake this up but this also has potential issues for the sea ice and the arctic across the CAA with rapid decline of snow across Canada from this. Just east of there had record warmth last year during mid to late summer.

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On 5/16/2023 at 9:29 PM, GaWx said:

 The MTD SOI continues to drop and is now down to -7 after eight days in a row of sub -10. That's the first time for that long of a sub -10 streak since Sept of 2019. The next seven days' SLPs at Darwin are forecasted to remain well above normal with a short term peak ~5/22. Also, Tahiti is starting from ~5/21 forecasted to have BN SLP for most of the rest of the month with some days MB.

 So, bottom line is that May will end up with a solid -SOI with sub -10 becoming increasingly likely, a strong leading indicator for El Niño.

 Followup: Today's SOI of -9.86 is the 10th -SOI in a row and brings down the MTD to -8. The SOI will rise tomorrow and it will be a close call as to whether or not we get the 11th -SOI in this streak. If we end up with -SOIs the next two days, the streak would very likely go a good number of days longer thanks to low Tahiti SLP with a small chance it could even go through the end of the month.

 The chance for a sub -10 for May, overall, continues to increase. Since 1950, there have been 11 sub -10 May SOIs. Only one of those 11 Mays didn't precede a new El Niño that autumn/winter. That was 2005. The reason May of 2005 was sub -10 was that the preceding Nino of 2004-5 was still lingering into April and May in the atmosphere, which sometimes happens.

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19 hours ago, GaWx said:

 Followup: Today's SOI of -9.86 is the 10th -SOI in a row and brings down the MTD to -8. The SOI will rise tomorrow and it will be a close call as to whether or not we get the 11th -SOI in this streak. If we end up with -SOIs the next two days, the streak would very likely go a good number of days longer thanks to low Tahiti SLP with a small chance it could even go through the end of the month.

 The chance for a sub -10 for May, overall, continues to increase. Since 1950, there have been 11 sub -10 May SOIs. Only one of those 11 Mays didn't precede a new El Niño that autumn/winter. That was 2005. The reason May of 2005 was sub -10 was that the preceding Nino of 2004-5 was still lingering into April and May in the atmosphere, which sometimes happens.

Followup: Today's SOI did rise but only barely/much less than I thought with it still down at -9.48. That now tells me that the -SOI streak is safe to continue for a good number more days with it now at 11 days. It should end up at 17+ days as it looks now.

 Due to the combo of way above normal Darwin and significantly below normal Tahiti SLP, the GFS and Euro are suggesting a sub -50 SOI is quite possible on May 23rd. That would mean the lowest daily SOI since at least the -52 of 2/17/2017 and possibly the lowest since the -58 of 2/6/2010! It would also mean the lowest daily May SOI since 1997.

 May MTD is now at -8.3. With this very strong -SOI period coming next week, a sub -10 May of 2023 is now just about a certainty. That is a very strong indicator of an upcoming El Niño of an unknown magnitude.

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Followup: Today's SOI did rise but only barely/much less than I thought with it still down at -9.48. That now tells me that the -SOI streak is safe to continue for a good number more days with it now at 11 days. It should end up at 17+ days as it looks now.
 Due to the combo of way above normal Darwin and significantly below normal Tahiti SLP, the GFS and Euro are suggesting a sub -50 SOI is quite possible on May 23rd. That would mean the lowest daily SOI since at least the -52 of 2/17/2017 and possibly the lowest since the -58 of 2/6/2010! It would also mean the lowest daily May SOI since 1997.
 May MTD is now at -8.3. With this very strong -SOI period coming next week, a sub -10 May of 2023 is now just about a certainty. 

The +IOD development is also looking more impressive. That will constructively interfere with the Nino. IMO a high-end strong Nino is looking more and more likely. We’ll see about super but if the Nino is in strong territory by the end of August, I would say that possibility goes up substantially. The 20C isotherm is just below the surface in regions 3 and 1+2….once that surfaces, it’s going to enhance Bjerknes feedback in those regions. Given that fact, I think it stays east-based and if it goes basin-wide it will have an east lean
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1 hour ago, snowman19 said:


The +IOD development is also looking more impressive. That will constructively interfere with the Nino. IMO a high-end strong Nino is looking more and more likely. We’ll see about super but if the Nino is in strong territory by the end of August, I would say that possibility goes up substantially. The 20C isotherm is just below the surface in regions 3 and 1+2….once that surfaces, it’s going to enhance Bjerknes feedback in those regions. Given that fact, I think it stays east-based and if it goes basin-wide it will have an east lean

Thanks. Per ONI I still favor a strong fall/winter peak but with high end moderate (+1.3 to +1.4) on the low side and super (+2.0+) on the high side. That puts me +1.6 to +1.9 for most likely.

 But per RONI assuming a -0.4 adjustment due to very warm overall tropical SSTAs, anywhere from a high end weak (+0.9) to low end super (near +2.0) is reasonably possible for the fall/winter peak with +1.2 to +1.5 for most likely.

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 Redifining Nino indices in a warming climate (relates to RONI):

https://iopscience.iop.org/article/10.1088/1748-9326/abe9ed/pdf

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Thanks. Per ONI I still favor a strong fall/winter peak but with high end moderate (+1.3 to +1.4) on the low side and super (+2.0+) on the high side. That puts me +1.6 to +1.9 for most likely.
 But per RONI assuming a -0.4 adjustment due to very warm overall tropical SSTAs, anywhere from a high end weak (+0.9) to low end super (near +2.0) is reasonably possible for the fall/winter peak with +1.2 to +1.5 for most likely.
------------
 Redifining Nino indices in a warming climate (relates to RONI):
https://iopscience.iop.org/article/10.1088/1748-9326/abe9ed/pdf

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16 minutes ago, snowman19 said:

This is very impressive agreement

It is, but it doesn’t mean that the mean forecast is more likely to be correct. 

Did these models predict that the trades would stay this strong all throughout May? Or did they underforecast those trades? 

@bluewave might know because he’s been tracking this closely. 

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