Let's talk ENSO

[weatherwiz]

Well this sucks.

The site I use to make composites and custom climo periods 

https://psl.noaa.gov/data/atmoswrit/map/

doesn't have precipitation within the list of options

I know there is this site

https://psl.noaa.gov/data/usclimdivs/

but you can't create custom climatologies ughhhhhhhhhhhhh

[40/70 Benchmark]

I should complete my wrap-up and grading of last season, this week, so I should probably tackle this near the end of May or during June at the latest.

[weatherwiz]

Well I have all composites (temperature anomalies, 500mb height anomalies, OLR anomalies, SLP anomalies) completed!!! I have this done for weak, moderate, and strong events focusing on winter as a whole (DJFM) and then looking at DJ and FM. I have a GIF composed of each individual year (and I've posted examples throughout this thread. 

But what I also did was create a composite grouping years together which I'll show below. The breakdowns are as follows

1) Weak EL Nino 

2) Moderate EL Nino

3) Strong EL Nino

4) Super-strong EL Nino

5) Modoki EL Nino

6) EL Nino Forcing (this means that tropical forcing/Walker Cell was displaced farther east then usual, which is the tendency for EL Nino events).

7) Neutral Forcing (while the tropical forcing/Walker Cell has the tendency to be displaced farther east, that is not always the case).

Note: Seasons in which the ONI or Ensemble ONI were borderline on the strength definition, I included the years within both sets.

[40/70 Benchmark]

2 minutes ago, 40/70 Benchmark said:

I have completed my El Nino composites by both intensity and orientation....those will be out in a blog post within the week.

I have determined intensity by mainly ONI, but not 100%....there is some consideration given to both time of peak and MEI....for instance, I consider 1987-1988 to be moderate for winter, even though it peaked as strong late in the summer. I also consider 2009-2010 as moderate, despite a 1.6 ONI peak narrowly qualifying it as strong. due to the weaker MEI (moderate)...I think this better reflects the forcing, as well.....because as you will see, weak of largely synonymous with modiko and east based strong. This makes sense, intuitively, since the stronger WWB needed to achieve a high ONI are not likely to allow the eastern regions to cool much.

 

[40/70 Benchmark]

Hello El Nino My Old Friend: El Nino Watch In Effect After Protracted La Nina

El Nino Comes in Many Shapes and Flavors

Finally, on the heels of three consecutive la nina events, an el nino watch has been issued for the first time in half a decade as of May 11. While there are no certainties with respect to anything pertaining to the atmosphere, the Climate Prediction Center (CPC) is more than 90% certain that el nino conditions will in fact develop and persist throughout the ensuing 2023-2024 boreal winter season. This level of confidence appears justified at this early juncture.

Here is an illustration of the latest guidance from May:

 

 

Statistical guidance is often very helpful in revealing the most climatologically favored outcome at longer lead times, however, caution is advised when said guidance is in great conflict with dynamical guidance. The latter of which is designed to incorporate what is actually going on in the atmosphere. In this instance, given that the current MAM ONI value is 0.1 and there are several examples of a large enough recovery between now and next fall to achieve to a powerful peak of el nino, the current dynamical mean of a 1.67 peak ONI during the OND tri monthly period seems like a reasonable first approximation. And thus the statistical guidance can be summarily dismissed until further notice. This is in accordance with latest CPC
estimation, which places the odds of a strong ONI peak of equal to or greater than 1.5 at 55%, which is exceptionally strong for such a long lead time. Although it is far too early to offer any definitive forecasting insight with respect to how the developing el nino will mold the coming winter season, there are some general inferences that can be made about how it could potentially impact the weather patterns.

Sorting El Nino by Intensity

A weak el nino is defined by CPC as a tri-monthly ONI peak of equal to or greater than .5 up through .9. Moderate is equal or greater to 1.0 up through 1.4. Strong, which is where guidance currently favors the developing events to peak, is anything equal or greater to 1.5 through 1.9. And an intense event, which remains a distinct possibility, is anything equal to or exceeding 2.0. There are only three el nino events since 1950 that the CPC definition of an intense el nino. They are the 1972-1973 (2.1 peak) event, the 1997-1998 (2.4) peak event and the el nino of 2015-2016 (2.6 peak). While the Eastern Mass Weather el nino intensity designations heavily incorporate ONI, there are other considerations, such as MEI and time of peak. Thus while the 1972-1973 event meets the CPC standard of an intense event per ONI, the MEI value during the winter was hardly considered strong, thus it is debatable how well coupled it remained with the atmosphere throughout the winter season. It is with this in mind that this particular season is considered as a "strong" event, rather than intense. Likewise, the 1987-1988 peaked as a strong 1.7 ONI value during the summer, but had weakened considerably by winter, this it is considered to be moderate, despite peaking as a strong ONI designation.

 

Here are the intense el nino composites, which are comprised of the 1982-1983, 1997-1997 and 2015-2016 seasons. The meteorological differences between the composites will be discussed in great this fall, and over course in the winter outlook.

 

Intense El Nino

 

Intense El Nino SST Anomaly Composite:

 

Intense El Nino H5 Composite:

 

 

                                                           

 

Intense El Nino Forcing Via Velocity Potential:

 

 

Intense El Nino Temperature Anomaly Composite:

 

                                       

Intense El Nino Precipitation Composite:

 

Very strong positive precipitation anomaly (near coast and se) and negative precipitation anomaly (Ohio River Valley) couplet due to presence of very powerful subtropical jet (STJ)

 

Strong El Nino

Strong El Nino SST Anomaly Composite:

 

Strong El Nino H5 Composite:

 

 

 

 

Strong El Nino Forcing Via Velocity Potential:

 

 

 

Strong El Nino Temperature Anomaly Composite:

 

 

Strong El Nino Precipitation Composite:

 

 

 

 

Moderate El Nino

Moderate El Nino SST Anomaly Composite:

 

 

Moderate El Nino H5 Composite:

 

 

 

Moderate El Nino Forcing Via Velocity Potential:

 

 

Moderate El Nino Temperature Anomaly Composite:

 

 

 

 

Moderate El Nino Precipitation Composite:

 

 

 

Weak El Nino

Weak El Nino SST Anomaly Composite:

 

Weak El Nino H5 Composite:

 

 

 

Weak El Nino Forcing Via Velocity Potential:

 

 

Weak El Nino Temperature Anomaly Composite:

 

 

 

Weak El Nino Precipitation Composite:

 

Drier due to a less pronounced STJ.

 

 

 

It is important to note that the weaker el nino events, which are also colder across the forecast area and feature more high latitude blocking, have the forcing more diffuse and focused further to the west. While the more intense events that feature milder winters for the forecast area and a notable dearth of high latitude blocking, are focused further to the east. Hence it is the stronger events that end up being more evenly distributed that present the greatest forecasting quandaries and it appears as though that may be precisely what is on tap this season.

 

El Nino Distinguished by Orientation

Generally speaking, stronger el nino events rate lower on the El Nino Modoki Index (EMI), and weaker events higher. Thus stronger events are generally biased to the east and stronger to the west. Currently, the developing el nino event it strongly biased to the east.

 

This is reflected by the negative EMI reading at this time.

 

However, there is a definitive consensus amongst the various Japanese Meteorological Association (JMA) ensemble members that the event will translate eastward throughout the summer, fall and into the winter. This is often the case with many el nino events, but the degree to which it occurs is dictated by many nuanced relationships between tropical wind and pressure patterns. This implies that a truly challenging seasonal forecasting effort may lie ahead.

There is plenty of time to dissect this further over the next several months as el nino continues to evolve, but for now, lets simply present the various composites.

 

East-Based El Nino

Given that the most intense el nino events are generally heavily eastern biased, there exists a negative correlation between the ONI and EMI. This is reflected well in the eastern-based SST composite.

 

East Based El Nino SST Anomaly Composite:

 

Note the similarities to the intense, and to a lesser, extent, the strong composites.

 

 

East-Based El Nino H5 Composite:

 

 

 

East-Based El Nino Forcing Via Velocity Potential:

 

 

 

East-Based El Nino Temperature Anomaly Composite:

 

 

 

East-Based El Nino Precipitation Anomaly Composite:

 

Wetter in general near the east coast due to the active STJ, but the positive precipitation anaomalies and adjacent negative precipitation anomalies are not as extreme as the intense composite.

 

 

 

Basin-Wide El Nino

Half (12) of the 24 el nino events since 1950 have been designated as basin-wide events.

 

Basin-Wide El Nino SST Anomaly Composite:

 

Similar to moderate composite.

 

Basin-Wide El Nino H5 Composite:

 

Element of high latitude blocking, as in moderate composite.

 

 

Basin-Wide El Nino Forcing Via Velocity Potential:

 

Forcing placement on par with moderate composite, but stronger and more focused.

 

Basin-Wide El Nino Temperature Anomaly Composite:

 

Cooler like moderate.

 

 

 

Basin-Wide El Nino Precipitation Anomaly Composite:

 

 

Modoki (West-Based) El Nino

Modoki el nino is often, not always, synonymous with weaker events.

 

Modoki El Nino SST Anomaly Composite:

 

Same placement as weak composite, but slightly greater anomaly.

 

 

Modoki El Nino H5 Composite:

 

Great deal of high latitude blocking, as in weaker events.

 

 

 

Modoki El Nino Forcing Via Velocity Potential:

 

Same placement as weaker events just east of the dateline, but stronger and more focused.

 

Modoki El Nino Temperature Anomaly Composite:

 

Interestingly enough, although the composite is comprised of stronger el nino events than the "weak" composite, the negative temperature anomalies are actually greater. This makes sense because the forcing is in the same place, just stronger and less diffuse relative to the weak composite.

 

 

 

Modoki El Nino Precipitation Anomaly Composite:

 

Drier than the east based composite, but not as dry as the weak composite.

 

 

 

Please stay tuned throughout the summer and autumn as these differences are further dissected within the context of the fledgling el nino in order to provide greater insight into the coming winter weather pattern.

 

[weatherwiz]

Question for @CoastalWx @ORH_wxman @40/70 Benchmark or really anyone who is much more knowledgeable than I am in this respect. 

I am doing some work with the PDO and ENSO phase. In assessing positive (warm) phase versus negative (cool) phase I am using this guideline from Stepen Hare and Nathan Mantua:

 

Now we know that the PDO tends to be in the warm phase during EL Nino episodes and the cool phase during La Nina episodes, however, that is not always the case. 

Below are ASON SST's during EL Nino events. Utilizing the graphic from above, I am focusing on SSTA patterns within the equatorial Pacific, west coasts of the United States, Canada, and Alaska, and the northern Pacific. 

I am cross referencing with the raw numbers from this site https://www.ncei.noaa.gov/access/monitoring/pdo/

 

One thing I'm noticing is I think the very warm waters associated with EL Nino across the equatorial Pacific are heavily skewing the raw PDO data. 

For example, here is 1913 PDO data for ASON (clearly the numbers are positive)

However, the SST configuration is not very reflective of a +PDO pattern 

So I guess two questions are:

1. When assessing PDO state what metrics should be considered to balance out how ENSO may skew the PDO (SSTs within the equatorial PAC)? 

2. If the SSTA configuration say from the west coast of the U.S. north across Alaska and north Pacific are more reflective of a negative (cool) phase but you have the warm SST's within the equatorial PAC due to EL Nino, what's the distinguisher to classify PDO state?

[40/70 Benchmark]

11 minutes ago, weatherwiz said:

Question for @CoastalWx @ORH_wxman @40/70 Benchmark or really anyone who is much more knowledgeable than I am in this respect. 

I am doing some work with the PDO and ENSO phase. In assessing positive (warm) phase versus negative (cool) phase I am using this guideline from Stepen Hare and Nathan Mantua:

 

Now we know that the PDO tends to be in the warm phase during EL Nino episodes and the cool phase during La Nina episodes, however, that is not always the case. 

Below are ASON SST's during EL Nino events. Utilizing the graphic from above, I am focusing on SSTA patterns within the equatorial Pacific, west coasts of the United States, Canada, and Alaska, and the northern Pacific. 

I am cross referencing with the raw numbers from this site https://www.ncei.noaa.gov/access/monitoring/pdo/

 

One thing I'm noticing is I think the very warm waters associated with EL Nino across the equatorial Pacific are heavily skewing the raw PDO data. 

For example, here is 1913 PDO data for ASON (clearly the numbers are positive)

However, the SST configuration is not very reflective of a +PDO pattern 

So I guess two questions are:

1. When assessing PDO state what metrics should be considered to balance out how ENSO may skew the PDO (SSTs within the equatorial PAC)? 

2. If the SSTA configuration say from the west coast of the U.S. north across Alaska and north Pacific are more reflective of a negative (cool) phase but you have the warm SST's within the equatorial PAC due to EL Nino, what's the distinguisher to classify PDO state?

I think you have touched upon part of the reason why PDO and PNA are not necessarily always matched on a seasonal level.

[CoastalWx]

23 minutes ago, weatherwiz said:

Question for @CoastalWx @ORH_wxman @40/70 Benchmark or really anyone who is much more knowledgeable than I am in this respect. 

I am doing some work with the PDO and ENSO phase. In assessing positive (warm) phase versus negative (cool) phase I am using this guideline from Stepen Hare and Nathan Mantua:

 

Now we know that the PDO tends to be in the warm phase during EL Nino episodes and the cool phase during La Nina episodes, however, that is not always the case. 

Below are ASON SST's during EL Nino events. Utilizing the graphic from above, I am focusing on SSTA patterns within the equatorial Pacific, west coasts of the United States, Canada, and Alaska, and the northern Pacific. 

I am cross referencing with the raw numbers from this site https://www.ncei.noaa.gov/access/monitoring/pdo/

 

One thing I'm noticing is I think the very warm waters associated with EL Nino across the equatorial Pacific are heavily skewing the raw PDO data. 

For example, here is 1913 PDO data for ASON (clearly the numbers are positive)

However, the SST configuration is not very reflective of a +PDO pattern 

So I guess two questions are:

1. When assessing PDO state what metrics should be considered to balance out how ENSO may skew the PDO (SSTs within the equatorial PAC)? 

2. If the SSTA configuration say from the west coast of the U.S. north across Alaska and north Pacific are more reflective of a negative (cool) phase but you have the warm SST's within the equatorial PAC due to EL Nino, what's the distinguisher to classify PDO state?

I think you should dive deeper into what each month looked like. Also, the PDO domain is large. In that mean image above, the cold pool typically seen does match closer to what we would see with a +PDO domain. I think also PDO includes sea level pressure anomalies which may help weed out any ENSO signal?

[weatherwiz]

17 minutes ago, CoastalWx said:

I think you should dive deeper into what each month looked like. Also, the PDO domain is large. In that mean image above, the cold pool typically seen does match closer to what we would see with a +PDO domain. I think also PDO includes sea level pressure anomalies which may help weed out any ENSO signal?

Yes, I believe PDO also incorporates SLP and surface wind stress. Incorporating SLP anomalies probably is a good idea when classifying PDO state during EL Nino (and La Nina regimes). 

I am very curious to see how the PDO progresses through the remainder of the fall. Based on raw PDO data, we're in a solid -PDO state and that massive warm pool in the north Pacific is reflective of that as well (only think really lacking is cooler waters off the western coasts). 

There have been very few winters where we had a strong EL Nino episode and a solidly -PDO state.  

[weatherwiz]

On 9/27/2023 at 12:11 PM, CoastalWx said:

I think you should dive deeper into what each month looked like. Also, the PDO domain is large. In that mean image above, the cold pool typically seen does match closer to what we would see with a +PDO domain. I think also PDO includes sea level pressure anomalies which may help weed out any ENSO signal?

so I've been working quite a bit on this the past week. Essentially, and this goes to an earlier post I made (either in this thread or the winter ENSO thread) but I'm an idiot. 

Issue is I make these composites and put into MS Paint and print them out and they're super small. When I was assessing the northern PAC SST structure I was focusing on the wrong area. I came to this conclusion when I was looking at ASON SSTA's for 1906. The raw number was fairly positive but my interpretation was a -PDO. My focus on SST structure in the north Pacific had been too far south  

[weatherwiz]

I'm wondering if I made a terrible mistake comparing variables to their respective climatology periods, especially with sea-surface temperatures. Per PDO dataset, the PDO phase was negative during ASON of 1921 (averaged value = -1.48). However, here are the SSTA's for that period using a climo period of 1891-1920.

Clearly, the PDO signal is very weak. 

Well I was doing some reading and I believe the current version of the PDO still uses a base climatology of 1971-2000. So here is the SSTA's compared to 1971-2000

Clearly this exhibits a negative PDO look. 

Now when dealing with these older years reliability of the data needs to be considered and the data set you use (HADISST, COBE, NOAA ERSST, etc). 

But the discrepancies above yield a significant question; How do you go about conducting analysis on these earlier years? I mean I suppose there is no right away. I mean if comparing to it's respective climo period, the PDO signal is very weak, but if comparing to a different period, maybe that yields a stronger signal. But the truth of the matter is you can't (I don't think compare a year to a set of years which hasn't happened yet. 

But it is very possible too that the data from that period is very scarce so would it be better to compare to a more recent period? Reading through literature there are questions regarding the reliability of the data from the 1800's to even like 1940. 

AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH 

[40/70 Benchmark]

22 hours ago, weatherwiz said:

I'm wondering if I made a terrible mistake comparing variables to their respective climatology periods, especially with sea-surface temperatures. Per PDO dataset, the PDO phase was negative during ASON of 1921 (averaged value = -1.48). However, here are the SSTA's for that period using a climo period of 1891-1920.

Clearly, the PDO signal is very weak. 

Well I was doing some reading and I believe the current version of the PDO still uses a base climatology of 1971-2000. So here is the SSTA's compared to 1971-2000

Clearly this exhibits a negative PDO look. 

Now when dealing with these older years reliability of the data needs to be considered and the data set you use (HADISST, COBE, NOAA ERSST, etc). 

But the discrepancies above yield a significant question; How do you go about conducting analysis on these earlier years? I mean I suppose there is no right away. I mean if comparing to it's respective climo period, the PDO signal is very weak, but if comparing to a different period, maybe that yields a stronger signal. But the truth of the matter is you can't (I don't think compare a year to a set of years which hasn't happened yet. 

But it is very possible too that the data from that period is very scarce so would it be better to compare to a more recent period? Reading through literature there are questions regarding the reliability of the data from the 1800's to even like 1940. 

AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH 

+3SD anomaly on the self-induced ice cream headache index.

[weatherwiz]

15 minutes ago, 40/70 Benchmark said:

+3SD anomaly on the self-induced ice cream headache index.

I've been reading through some papers and doing some additional research. What I'm going to mention below is something I already knew but it always helps to just verify what you're thinking. 

When dealing with these early years there needs to be extreme caution given the uncertainties which exist with the viability of the data. There also needs to be an understanding of the strengthens and weaknesses of the dataset being used. For example, with my SST stuff, my source is the HADISST dataset. There appears to be some question marks with this dataset after the 1980's due to a cold bias. Also, the earlier years there is big question marks within the northern latitude oceans (which I think is reflected very well using an 1881-1910 / 1891-1920 climo period). 

I'm just further trying to understand all the biases, strengthens, and weaknesses because at some point when I start blogging about this more or making a website I want to be sure I am properly communicating this and explaining any results I am presenting are just based on my choosing of the dataset and periods and results could differ slightly if using other methods. 

[40/70 Benchmark]

36 minutes ago, weatherwiz said:

I've been reading through some papers and doing some additional research. What I'm going to mention below is something I already knew but it always helps to just verify what you're thinking. 

When dealing with these early years there needs to be extreme caution given the uncertainties which exist with the viability of the data. There also needs to be an understanding of the strengthens and weaknesses of the dataset being used. For example, with my SST stuff, my source is the HADISST dataset. There appears to be some question marks with this dataset after the 1980's due to a cold bias. Also, the earlier years there is big question marks within the northern latitude oceans (which I think is reflected very well using an 1881-1910 / 1891-1920 climo period). 

I'm just further trying to understand all the biases, strengthens, and weaknesses because at some point when I start blogging about this more or making a website I want to be sure I am properly communicating this and explaining any results I am presenting are just based on my choosing of the dataset and periods and results could differ slightly if using other methods. 

I only go back to 1950.

[weatherwiz]

30 minutes ago, 40/70 Benchmark said:

I only go back to 1950.

I've been debating on just focusing on 1950 onwards as well, however, we do have enough reliable data to incorporate years prior to 1950, it's just there has to be an understanding that the data be used with caution. The issue with just going from 1950 onwards is you're really limiting your dataset and eliminating potential outcomes or probabilities. 

 

[weatherwiz]

Going back through composites and I think I need to re-think my scale and interval levels, particularly with OLR. How I came up with my scales I used was just looking through several periods and finding values that were in the middle. For OLR I used -30 to +30 with an interval of 10. I think using this scale is generating a bias when assessing the maps. Where tropical forcing is located is important, but I have to wager that the strength of the tropical forcing is just as important. With my scale, I think it is making some years look "intense" when the tropical forcing weak probably weak. 

I see on the NOAA daily CPC page the scale they have is -80 to +80 with an interval of 15...that might be a bit much though for composites. Since the goal with the composites is to easily compare periods, it's important the scale remain constant. 

[CoastalWx]

@40/70 Benchmark  You see this link before?  https://psl.noaa.gov/enso/difference/

 

 

 

[40/70 Benchmark]

3 minutes ago, CoastalWx said:

@40/70 Benchmark  You see this link before?  https://psl.noaa.gov/enso/difference/

 

 

 

No...bookmarked.

Evident that 1997 probably would have been decent if it weren't so overwhelmingly powerful.

[weatherwiz]

1 hour ago, CoastalWx said:

@40/70 Benchmark  You see this link before?  https://psl.noaa.gov/enso/difference/

 

 

 

Woah that is awesome 

[yoda]

1 hour ago, CoastalWx said:

@40/70 Benchmark  You see this link before?  https://psl.noaa.gov/enso/difference/

 

 

 

Thanks... hadn't seen that before either

[CoastalWx]

1 hour ago, 40/70 Benchmark said:

No...bookmarked.

Evident that 1997 probably would have been decent if it weren't so overwhelmingly powerful.

 

6 minutes ago, weatherwiz said:

Woah that is awesome 

Saw it in an email thread. Pretty cool.

[Typhoon Tip]

I've seen that site before. It's a nice quick expose' without a bunch of busy data entry that's not very well described ..making the user feel a popsicle headache coming on.

I wish they'd do some other index spaces.