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2015 ENSO super thread


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Hey Don,

 

No argument at all, as I am not versed well enough in the particulars of ENSO to even formulate a worthy retort, but how can you discern that 3.4 is favored for the largest departures at this juncture?

Subsurface?

Region 1.2 is still the warmest, no?

I know it is highly unstable, so....

sstaanim.gif

You can see at the end how the largest SST Anomalies shift towards Regions 3 and 3.4.

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I'm fairly confident at this juncture that region 1+2 warming is nearing or has already reached completion, namely, further ENSO warming will be restricted to regions 4, 3.4 and 3. This is apparent through an examination of subsurface anomaly trends over the past month; subsurface areas to the east of 100W longitude to 80W are now close to normal w/ pockets of cooler than normal developing immediately adjacent to the South American coastline. Region 3.4 has fallen to +1.76c on tropical tidbits, due to a recent weakening of WWB's, and the first positive daily SOI value in quite awhile. However, I expect renewed WWB bursts over the coming 1-2 months, promoting a maintenance of +2.0c or greater weekly anomalies. With that being said, I see no reason to abandon my original call from a few months ago for the peak trimonthly ONI value of +1.7c to +1.95. I still do not believe this event has the classic precursor pattern for a super Nino trimonthly classification of +2.0c or greater, akin to years such as 82/83, 97-98. There are already potential indications of a "cap" on the peak magnitude of this +ENSO event.

 

Subsurface trends. Note the progression of cooling in regions 1+2, and orientation of warmest anomalies from the central part of region 3.4 eastward through region 3. I generally expect a maintenance of this paradigm with possible gradual shifts wwd in the coming weeks.

 

nflk4i.gif

 

 

SST's around Australia are undergoing a warming trend, which indicates to me that there is a limit on the magnitude of WWB's, and a peak near 97-98 intensity is highly unlikely.

 

With respect to the NPAC, there has been a cooling of waters recently. As I've opined in prior posts, I wouldn't be surprised to see a significant decrease in the coverage / magnitude of positive SSTA, particularly in mid/late autumn as the mid latitude jet shifts equatorward. While the sample size is not great, historical precedent suggests that achieving a -EPO in the means will be quite difficult, unless a pattern akin to 2002-03 develops, which was a weaker El Nino event. There is time to monitor this. I'm not necessarily as concerned with the progression of NPAC SSTA, as their eventual fate will be predicated upon the ENSO forcing and tropical Pacific tendencies.

 

 

cdas-sflux_ssta7diff_global_1.png

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Sept 3rd MEI Update...

 

"Compared to last month, the updated (July-August) MEI has increased significantly by 0.39 standard deviations to +2.37, or the 2nd highest ranking, surpassed only in 1997 at this time of year. This new peak value of the current event ranks third highest overall at any time of year since 1950, with 1982-83 and 1997-98 remaining in a 'Super El Niño' club of their own (for now), with peak values around +3 standard deviations.

 

Looking at the nearest 6 rankings (+1/-5) in this season, and excluding cases with declining July-August values compared to earlier in the year gives us the same five 'analogues' as last month: 1965, 1972, 1982, 1987, and 1997. All five maintained strong El Niño status through at least December of their respective calendar years. However, three of them ('65, '72, and '97) peaked already in July-August (the current season), followed by minor declines by the end of the year. Only 1982 showed continued growth right into the following year, while 1987 had already peaked back in May of that year. 

 

El Niño conditions are guaranteed to persist into the upcoming boreal winter season, most likely at strong levels for much of that period. Whether it will reach the elusive 'Super El Niño' level remains to be seen. In addition, typical El Niño impacts will be supported by positive PDO conditions that have endured since January 2014, reaching record levels from December 2014 through February 2015. Daily updates of the ENSO status can be found at the TAO/TRITON website, showing a renewed westerly wind surge near the dateline as of the beginning of September." 

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Here's an alternate view of East vs. Central based SST conditions based on the E and C indices from Takahaski et al. (2011) - http://www.met.igp.gob.pe/datos/EC.txt

 

Orange lines = strong ninos

Blue lines = moderate ninos

 

The shading is as follows (my subjective interpretation)...

Pink shaded area = East based SST conditions

White area = Basin wide SST conditions

Blue shaded area = Central based SST conditions 

 

Dashed area is the key fall to early winter timeframe for winter interests

 

Evs_W_Index.png
 

Evs_W_Pattern.png
 
For additional info, see... 
 
 
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Oct 3rd MEI update...

 

"Compared to last month, the updated (August-Spetember) MEI has increased by 0.16 standard deviations to +2.53, or the 2nd highest ranking, surpassed only in 1997 at this time of year. This new peak value of the current event ranks third highest overall at any time of year since 1950, closing in on 1982-83 and 1997-98 with 'Super El Niño' values around +3 standard deviations.

 

Looking at the nearest 6 rankings (+1/-5) in this season, and excluding cases with declining August-September values compared to three months prior gives us five 'analogues': 1957, 1965, 1972, 1982, and 1997. All five maintained strong El Niño status for at least another four months (Dec-Jan). In terms of the timing of their peak ranks, the two biggest Niño events bracket the range of observed outcomes: 1997 peaked from May-June through October-November, while 1982-83 hung on to the pole position from November-December through April-May 1983.

 

El Niño conditions are guaranteed to persist into the upcoming boreal winter season, most likely at strong levels for the full period. Whether it will reach the elusive 'Super El Niño' level around +3 standard deviations remains to be seen, but has become more likely over the last few months."

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Also, don't like the recent cooling in the GOA, which isn't really reflected in the anom maps above.

 

Don't spend time worrying about the GOA. Nino climo features BN SSTA's through the majority of that region due to persistent low pressure/heights oscillating through fall/winter. What's happening in that region is to be expected and not a bad sign of anything. 

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Don't spend time worrying about the GOA. Nino climo features BN SSTA's through the majority of that region due to persistent low pressure/heights oscillating through fall/winter. What's happening in that region is to be expected and not a bad sign of anything. 

 

Ok....would still like to see the less of an east-based signature for the nino structure, though.  Who knows how blocking evolves, but with a strong, fairly east-biased nino, I would be inclined to think that without a strong blocking signature (which we don't know about yet), the STJ is going to overwhelm the pattern, especially here in the SE.  I guess the fact that several seasonal models show a favorable pattern is good.  But I'm really wanting to see eastern enso areas cool relative to the central and western zones.

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Still much too east-based for my liking. Also, don't like the recent cooling in the GOA, which isn't really reflected in the anom maps above.

CR - at first glance, yes it does have an east based look.  I suppose the devil is in the details - by comparison, you can see that in '97 there was a much stronger east region signal (more warmth east of say 110W)...that's the main reason why it registers much higher in the base chart.  Of course, this is only nino base with respect to SSTs - there are other parameters to consider such as VP anomalies, OLR, Omega.

 

2015_1997.png
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CR - at first glance, yes it does have an east based look.  I suppose the devil is in the details - by comparison, you can see that in '97 there was a much stronger east region signal (more warmth east of say 110W)...that's the main reason why it registers much higher in the base chart.  Of course, this is only nino base with respect to SSTs - there are other parameters to consider such as VP anomalies, OLR, Omega.

 

2015_1997.png

 

Another key difference between 2015 & 1997 is in the northern Pacific.  There were two distinct, robust pools of cold water around 40N near the date line in 1997.  In 2015, they aren't as noteworthy, though I doubt this will help our odds of snow at all this winter.

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