2014 ENSO Mega Thread

[hurricaneman]

Hi guys,

 

The latest European weeklies are now isolating another period of strong anomalous lower tropospheric westerly wind flow near the Date Line late April in through early May.  Now while this may not be a true WWB in nature (reversal of trades to westerlies at the surface), it will still likely result in weak trade flow near the date line and to the west thereafter at a later time. With the structure of SSTs in its current state, I still see signs for this Nino to be a Full Basin event and not a Modoki. Of course there is still uncertainty and time will tell, but I'm still placing bets in the full basin Nino camp.  

 

Did a quick analysis understanding the differences between Full-basin Ninos and Modoki's. With regards to tropical cyclone statistics over the Atlantic, Full-basin Nino's average 7 named storms, 3 hurricanes, 1 major hurricane. Modoki's that are expressed during the JJAS period often experience higher TC stats, with 11 named storms, 6 hurricanes, and 2 major hurricanes.

Its already showing signs that its going to be a traditional El Nino while JB is still honking the Madoki mostly because of the +SOI which is fundamentially flawed because one has to look at all factors like you have and one thing that has gotten my attention the last 2 months is that subsurface pool of +6 anomolies and  they are indeed surfacing in the eastern parts of the ENSO

[csnavywx]

WWV (warm water volume) anomalies are the highest since summer '97:

[AlaskaETC]

WWV (warm water volume) anomalies are the highest since summer '97:

 

Damn..

[The_Global_Warmer]

If the dmi ssta set is right the last two days nino may be finally coming.

 

 

[skierinvermont]

The western edge of the warm water pool has weakened over the last 2 weeks. Unless it restrengthens very soon I think super-El Nino can be ruled out. The SOI has been too slow to become negative. 

 

April '97 was solidly negative at -14.4.. this April has been around +5. The the upper ocean anomalies are still large from the warm pool that has been surfacing/moving east the last 4 months, the anomalies at 100-200m in the central pacific have been cooling. April '97 maintained warm waters here even as the original warm pool moved east.. it was continually re-building in the central pacific subsurface.

[csnavywx]

Careful using SOI verbatim at the moment. There's been a couple of decent tropical disturbances recently (and there currently is one) near Darwin, causing surface pressure there to be lower than it otherwise would be. Regardless, 30 day SOI is higher than the 97 event at this time, though it's difficult to say what effect this will ultimately have, given recent WWB activity over the past 1-2 weeks.

 

Also:

 

 

 

 

Our wave is a little further along than April of 1997 was (WWB activity and the EKW surge was a few weeks ahead of 97 this year). In May of 97, cold anomalies had significantly eroded the western extent of the subsurface warm pool as well.

 

I don't think it's really possible to be able to tell the ultimate strength of this event one way or another yet.

[bluewave]

The SOI isn't following the pattern that proceeded the super El Ninos of 82-83 or 97-98.
Both those events began with a very strong SOI drop that held after the first

month and intensified. The quick reversal now isn't following that pattern so I don't think that

this El Nino will reach those levels. I believe that the -PDO era that we have been 

in since 1999 with the record strong trades near the dateline along with the

record breaking positive SOI levels make such an outcome less likely this time around.

 

 

[skierinvermont]

csnavy - I don't think it's simply a matter of being farther along. The EKW in 1997 was back building as it moved eastward. Not so this time.

There's still plenty of time for the SOI to reverse and to replenish the warm pool. But I question whether it can come close to 1997 at this point. 

[csnavywx]

57-58 and 72-73 were substantially weaker with SOI values yet had ONI peaks of 1.8 and 2.1 respectively.

 

Thus the danger of small sample sizes. While still useful to a degree, SOI is overly simplistic since the metric is JUST MSL pressure differential. We've got far better tools nowadays.

[csnavywx]

57-58 and 72-73 were substantially weaker with SOI values yet had ONI peaks of 1.8 and 2.1 respectively.

 

Thus the danger of small sample sizes. While still useful to a degree, SOI is overly simplistic since the metric is JUST MSL pressure differential. We've got far better tools nowadays.

Also, I forgot 65-66, which had an ONI peak of 1.9.

[csnavywx]

csnavy - I don't think it's simply a matter of being farther along. The EKW in 1997 was back building as it moved eastward. Not so this time.

There's still plenty of time for the SOI to reverse and to replenish the warm pool. But I question whether it can come close to 1997 at this point. 

You could be right. I'm partially speculating since there's a gaping hole in the partially collapsed TAO monitoring system that would really answer the question. Unfortunately there is no data between 155 and 110W along the equator to really confirm that. We're flying partially blind wrt to the subsurface at the moment.

[bluewave]

57-58 and 72-73 were substantially weaker with SOI values yet had ONI peaks of 1.8 and 2.1 respectively.

 

Thus the danger of small sample sizes. While still useful to a degree, SOI is overly simplistic since the metric is JUST MSL pressure differential. We've got far better tools nowadays.

 

We aren't talking 3.4 ONI when we refer to 97 being a super El Nino. Nino 1+2 made it to +4.6 in August and stayed above 4 into January.

None of the current modeling comes close to those levels. At this early time, most modeling has the warmest

waters west of 1+2 over 3.4 which would make this a centrally based event and not a super east based event.

 

 

13AUG1997 25.4 4.6 

07JAN1998 28.0 4.0

 

[csnavywx]

We aren't talking 3.4 ONI when we refer to 97 being a super El Nino. Nino 1+2 made it to +4.6 in August and stayed above 4 into January.

None of the current modeling comes close to those levels. At this early time, most modeling has the warmest

waters west of 1+2 over 3.4 which would make this a centrally based event and not a super east based event.

 

 

13AUG1997 25.4 4.6 

07JAN1998 28.0 4.0

 

nino12Mon.gif

Well, that's your personal definition of a super Nino. That's fine, but I'd like to get a consensus on what we should use to classify a super Nino if we're going to keep referring to it in this thread. I was using ONI since it's general convention.

[GaWx]

Fwiw, the latest weekly for Niño 1+2 was just released and has it 0.8 warmer than the prior week's -0.7 at +0.1. However, this area is much more volatile than the regions to the west.

[ORH_wxman]

Fwiw, the latest weekly for Niño 1+2 was just released and has it 0.8 warmer than the prior week's -0.7 at +0.1. However, this area is much more volatile than the regions to the west.

 

 

It should increase pretty rapidly I think over the next few weeks as the subsurface warm pool has migrated eastward toward that region and should be surfacing...however, I am also agreeing with those leaning against a Nino of magnitude similar to '97-'98 or '82-'83 since the subsurface warmth has shrunken as it moves east and has not been replenished very much in the central Pacific.

 

I'd lean more toward a strongish basin wide event at the moment, though there should always be the caveat that ENSO predictions in the springtime are subject to large errors.

[GaWx]

It should increase pretty rapidly I think over the next few weeks as the subsurface warm pool has migrated eastward toward that region and should be surfacing...however, I am also agreeing with those leaning against a Nino of magnitude similar to '97-'98 or '82-'83 since the subsurface warmth has shrunken as it moves east and has not been replenished very much in the central Pacific.

 

I'd lean more toward a strongish basin wide event at the moment, though there should always be the caveat that ENSO predictions in the springtime are subject to large errors.

 

 All of what you say sounds reasonable to me. Although the PDO has gone away from its negative state in recent months, I assume we're still within a -PDO regime and will be for a good number of years to come. I think that this -PDO regime is sort of fighting against the development of a super Nino like 82-83 or 97-98. The average strength of Ninos has been weaker during -PDO regimes vs. +PDO regimes. That being said, I agree that a strongish basin wide event (say, within the +1.5 to +2.0 corridor for Nino 3.4) does seem reasonable considering the still very warm subsurface in the east.

[skierinvermont]

Another difference with 97-98 is the the subsurface OHC anomaly reached +2.17 in April and stayed above +2 for several months. This year we peaked at +1.7 April 1st and have dropped to +1.3 since then. I think this is because the trades have not really subsided as in 1997 (not just measuring by the SOI) and the warm pool is not really replenishing in the central pacific... it's just moving east and gradually being eroded by some moderate trade winds.

 

I still think the trade winds will subside but I don't think >+2.0 for 3.4 is at all likely. I'd predict something like +1.5 +/- .5. 

[csnavywx]

1997

 

 

 

2014

[csnavywx]

Trades are pretty similar so far on each year and they're pretty weak right now (scales are a bit different, so be wary of that). The biggest difference I can see is the strength of the latest WWB. Of course, the big haymaker for 97 was the late May WWB.

[ORH_wxman]

Current weak WWB trying to cross the dateline, but it looks like it is forecasted to fall apart. There's a newer burst of easterlies that try and approach the dateline from the west later in the period...that would set back the Nino a bit...but we'll see if that verifies.

 

[mupawxnut]

I have always had that gut feeling that El Nino would go bust.  Hello, La Nina!!

Current weak WWB trying to cross the dateline, but it looks like it is forecasted to fall apart. There's a newer burst of easterlies that try and approach the dateline from the west later in the period...that would set back the Nino a bit...but we'll see if that verifies.

 

[ORH_wxman]

 

I have always had that gut feeling that El Nino would go bust.  Hello, La Nina!!

No way, El Nino is still very likely...but it may not get as strong if we are getting some easterly bursts to hinder the development at times. The ball is already rolling too much I think to have a neutral or La Nina.

[mupawxnut]

No way, El Nino is still very likely...but it may not get as strong if we are getting some easterly bursts to hinder the development at times. The ball is already rolling too much I think to have a neutral or La Nina.

Then what happened with 2012?

[The_Global_Warmer]

Then what happened with 2012?

 

 

I don't know but current TAO subsurface has 6C+ anomalies over the Eastern Pac equatorial line.

 

In 2012 at this point it looked nothing like this.

 

 

 

 

[ORH_wxman]

Then what happened with 2012?

 

 

Easterlies chewed up the subsurface warmth as it tried to push east and rise to the surface....but that warm pool was weaker. This one is potent in the eastern PAC...so even with some hindering easterly anomalies interfering from time to time, the warmth should be enough to get an El Nino.

 

 

But as you can see from the subsurface charts, the central Pacific subsurface has weakened which may prevent this from becoming very strong. Especially if we continue to see some easterly bursts mixed in.

[phil882]

OSCAR 5-day mean centered on 27 April shows significant westerly currents across the Pacific. There are also two distinct oceanic kelvin waves, one near the South American coastline (which resulted in the substantial propagation of positive sub-SSTA into the EPAC along the equator). There is also another developing oceanic kelvin wave near the Maritime continent which should result in another push of + surface and sub-SSTA into the CPAC and EPAC over the coming month.

 

Paul Roundy gave a good discussion earlier this afternoon suggesting that the last oceanic kelvin wave was enough to modify the base state of the Pacific favoring westerly surface oceanic currents. FWIW April-May 1997 saw similar magnitude oceanic kelvin waves propagating through the Pacific around this time.

 

[easternsnowman]

Those who were thinking this will be as strong as 97-98 likely are wrong but a moderately strong el nino such as 1 57-58 or 2009-10 us quite possible.

[The_Global_Warmer]

OSCAR 5-day mean centered on 27 April shows significant westerly currents across the Pacific. There are also two distinct oceanic kelvin waves, one near the South American coastline (which resulted in the substantial propagation of positive sub-SSTA into the EPAC along the equator). There is also another developing oceanic kelvin wave near the Maritime continent which should result in another push of + surface and sub-SSTA into the CPAC and EPAC over the coming month.

 

Paul Roundy gave a good discussion earlier this afternoon suggesting that the last oceanic kelvin wave was enough to modify the base state of the Pacific favoring westerly surface oceanic currents. FWIW April-May 1997 saw similar magnitude oceanic kelvin waves propagating through the Pacific around this time.

 

 

 

 

That graphic you posted looks very ominous.  That second kelvin wave has started to make an impact the last 10 days or so.  The CPC has shown 3C+ area out between 160-180E move Eastward the last two weeks and grow warmer with two weeks ago the 3C+ out there being gone.  Now this area is warming up again.

 

 

how long do these Kelvin waves last?  Does another atmospheric process come into play and disrupt them?

 

What is this second wave going to do to reinforce the first wave?

 

[phil882]

Those who were thinking this will be as strong as 97-98 likely are wrong but a moderately strong el nino such as 1 57-58 or 2009-10 us quite possible.

 

Still really too early to tell... 1997 really started to significantly ramp up during May. Its quite clear the next Oceanic Kelvin wave is developing right now and starting to propagate towards the dateline. 

 

That graphic you posted looks very ominous.  That second kelvin wave has started to make an impact the last 10 days or so.  The CPC has shown 3C+ area out between 160-180E move Eastward the last two weeks and grow warmer with two weeks ago the 3C+ out there being gone.  Now this area is warming up again.

 

 

how long do these Kelvin waves last?  Does another atmospheric process come into play and disrupt them?

 

What is this second wave going to do to reinforce the first wave?

 

 

Well first its important to note that oceanic kelvin waves propagate much slower than atmospheric kelvin waves and it takes several months to propagate across the Pacific Ocean... but to answer your question, the first Kelvin Wave was so strong it was able to modify the base state of the ocean (meaning westerly ocean currents are now favored). When oceanic kelvin waves reach the South American coastline, they tend to reflect back as slower upwelling oceanic Rossby waves (which upwell cooler water). But since the base state has been modified to favor westerly ocean currents, the effects of these eastward moving waves are mitigated, while future oceanic kelvin waves are enhanced.

 

If the base state wasn't modified, then between the oceanic kelvin waves (the area around 180-140W) should have switched back to easterly ocean currents. Based on this observation alone, it suggests that it will be extraordinarily difficult, if not impossible, to impede the positive feedback cycle that has started towards El Nino, since the background state further enhances westerly oceanic kelvin wave magnitude. 

[Dsnowx53]

Still really too early to tell... 1997 really started to significantly ramp up during May. Its quite clear the next Oceanic Kelvin wave is developing right now and starting to propagate towards the dateline. 

 

 

Well first its important to note that oceanic kelvin waves propagate much slower than atmospheric kelvin waves and it takes several months to propagate across the Pacific Ocean... but to answer your question, the first Kelvin Wave was so strong it was able to modify the base state of the ocean (meaning westerly ocean currents are now favored). When oceanic kelvin waves reach the South American coastline, they tend to reflect back as slower upwelling oceanic Rossby waves (which upwell cooler water). But since the base state has been modified to favor westerly ocean currents, the effects of these eastward moving waves are mitigated, while future oceanic kelvin waves are enhanced.

 

If the base state wasn't modified, then between the oceanic kelvin waves (the area around 180-140W) should have switched back to easterly ocean currents. Based on this observation alone, it suggests that it will be extraordinarily difficult, if not impossible, to impede the positive feedback cycle that has started towards El Nino, since the background state further enhances westerly oceanic kelvin wave magnitude. 

 

 

Yeah, it's all the feedback cycle. Another key is that since the Kelvin Wave was strong enough to modify the base state of the ocean by favoring westerly ocean currents as well as flattening the thermocline, then any associated upwelling cycle that occurs will be upwelling water that is not as cool as it usually is...thus the warm anomaly...this reinforces the warm anomalies that help to weaken the Walker Circulation, and weaken the trade winds to begin with. 

 

Seeing those strong depth anomalies that far east is certainly an indicator that the thermocline has flattened and the base state has changed. This should favor more sustained WWBs.