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2015 ENSO super thread


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May IRI update is in.  As expected based on Nino monitoring, the May release of the ENSO models is showing higher peak strength for the Nino this Fall.  Here's the Nino tri-monthly SST peak on the April and May IRI model releases...

 

Dynamical Models 

April: 1.4

May: 1.7

 

Statistical Models

April: 0.9

May: 1.2

 

All Models

April: 1.1

May: 1.5

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Per Cowan, Niño 3.4 is down to +0.81, the lowest since mid April and down from the multiyear high at over +1.2. I'm assuming this is just a temporary cooling, especially considering how strongly negative has been the SOI in recent weeks:

http://www.tropicaltidbits.com/analysis/nino34.png

 

Yes, but Nino 1+2 are still close to their multiyear peaks.  It's inevitable that 3.4 will rise again as the warm subsurface anomalies reach the surface in the 1+2 region and inevitably get swept westward by the prevailing currents. 

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May IRI update is in.  As expected based on Nino monitoring, the May release of the ENSO models is showing higher peak strength for the Nino this Fall.  Here's the Nino tri-monthly SST peak on the April and May IRI model releases...

 

Dynamical Models 

April: 1.4

May: 1.7

 

Statistical Models

April: 0.9

May: 1.2

 

All Models

April: 1.1

May: 1.5

what are the number thresholds for weak, moderate, and strong?

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what are the number thresholds for weak, moderate, and strong?

 

 They will vary to some extent, but I count up through +1.0 as weak, 1.1 to 1.5 as moderate, and 1.6+ as strong.

 

 Some will say 1.0, itself, is moderate and 1.5, itself, is strong. The exact breakdown isn't that significant.

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what are the number thresholds for weak, moderate, and strong?

 

Like GAwx said, it will vary.  I don't think there are official thresholds.  However, because SSTs are only relevant when the ocean-atmosphere are coupled, I don't bother with ONI.  MEI is a better quantifier of coupling.

 

The last MEI for the MarApr bimonth was almost 1.00.  The next update will come out in about 2 weeks, and it should be quite a bit higher based on what we've seen in the tropical Pacific.  To give you some perspective, 1997, which developed similarly to the present event, peaked at 3.005 in AugSep (but was only 0.537 in MarApr) and 1982-83, which followed the typical devleopment sequence peaked at 3.024 in FebMar.

 

What stands out to me is that the current el Nino has strengthened the Hadley cell to a pace well ahead of any other years that I've seen at this point.  1957, a decent analog, never looked like this in the tropics during the summer, and 1997 was nowhere near this organized at this early stage.  That's not to say this el Nino won't go through a weakening phase, or will surpass 1997, but it seems extremely healthy to me.  One of the best we've seen in a long time, imo.

 

Anyway, peruse the MEI for yourself here: http://www.esrl.noaa.gov/psd/enso/mei/table.html

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1982 and 1997 were first year el ninos...this is a second year nino similar to 1905, 1930 and 1940 on the mei scale...1987 could be considered also...

1987...+2.131...JMA +14

1940...+1.441...JMA +11

1930...+1.955...JMA +19

1905...+1.954...JMA +15

...........................................................

strongest mei analogs...

1982...+3.024...JMA +28

1997...+3.005...JMA +33

1878...+2.495...JMA +22

1992...+2.269...JMA +14

1941...+2.269...JMA +11

1987...+2.131...JMA +14

1902...+2.039...JMA +14

1993...+1.992...JMA +14

1972...+1.896...JMA +20

1888...+1.893...JMA +23

1919...+1.753...JMA +14

1900...+1.713...JMA +16

1926...+1.602...JMA +16

1915...+1.556...JMA +05

1897...+1.543...JMA +18

2010...+1.524...JMA +14

1965...+1.477...JMA +13

1958...+1.472...JMA +12

 

2014...+0.932...JMA +10

 

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Between sub surface and equatorial wind anomalies.

A strong Nino is looking more and more likely

SOI might say otherwise. Recent trends show a steady, possibly significant + trend, reflected in the 30- and 90-day values. Daily values have skyrocketed to more than +15 as well, and the overall frequency of negative dailies has steadily dropped.

 

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/

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SOI might say otherwise. Recent trends show a steady, possibly significant + trend, reflected in the 30- and 90-day values. Daily values have skyrocketed to more than +15 as well, and the overall frequency of negative dailies has steadily dropped.

 

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/

So far, this is just a short term change, which isn't at all unusual, especially this early. I wouldn't put much significance in it at all at this point.

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it hasn't reach 1997 soi yet...

1997 138 1010.30 1010.70  -14.781997 139 1009.52 1011.00  -23.011997 140 1008.95 1010.80  -25.881997 141 1009.33 1011.60  -29.041997 142 1009.86 1012.20  -29.621997 143 1008.81 1012.75  -41.871997 144 1010.22 1013.25  -34.881997 145 1011.30 1013.20  -26.271997 146 1010.37 1013.70  -37.181997 147 1010.41 1012.80  -30.001997 148 1011.92 1012.70  -17.65 May 28th...1997 149 1012.76 1013.15  -14.681997 150 1010.02 1013.95  -41.781997 151 1006.08 1015.75  -85.721997 152 1006.00 1015.70  -77.261997 153 1009.86 1015.50  -48.701997 154 1011.30 1015.25  -36.831997 155 1012.38 1015.90  -33.761997 156 1013.80 1014.80  -16.091997 157 1014.72 1014.95  -10.651997 158 1014.91 1015.90  -16.011997 159 1014.11 1016.90  -28.661997 160 1012.68 1016.55  -36.221997 161 1010.38 1015.10  -42.211997 162 1008.62 1014.45  -49.991997 163 1012.25 1014.45  -24.481997 164 1015.27 1014.60   -4.341997 165 1015.26 1013.50    3.321997 166 1014.11 1013.75   -6.521997 167 1009.58 1015.25  -48.871997 168 1008.01 1015.50  -61.701997 169 1010.45 1014.95  -40.701997 170 1014.88 1015.05  -10.211997 171 1016.36 1015.75   -4.761997 172 1014.62 1016.55  -22.601997 173 1011.96 1015.20  -31.831997 174 1011.22 1013.70  -26.461997 175 1012.38 1012.90  -12.671997 176 1014.86 1012.70    6.161997 177 1015.08 1012.75    7.361997 178 1013.71 1013.05   -4.391997 179 1011.87 1013.35  -19.431997 180 1011.27 1013.05  -21.541997 181 1012.31 1012.45  -10.02
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That screams major East based Nino about to erupt.

 

We are very well-coupled right now to be sure; as long as there is warm water to be drawn to the surface, we will continue to do so.  I think that's one reason GaWx is right in not worrying about the SOI right now.  el Nino is present and going strong no matter the SOI.  Personally, I am still looking forward to the next bimonthly MEI.  I think it will reflect a very healthy el Nino and maybe one of the strongest ever for the AprilMay bimonth.

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Yes, but Nino 1+2 are still close to their multiyear peaks.  It's inevitable that 3.4 will rise again as the warm subsurface anomalies reach the surface in the 1+2 region and inevitably get swept westward by the prevailing currents.

I see that the Cowan Niño 1 + 2 has fallen from +2.3 to +0.9 in a mere six days and it is still falling fast! This could easily fall to near +0.5 based on its still steep drop. However, I do wonder about its accuracy. Compared to NCEP's +2.6 of last week, Cowan's graph was about 0.8C too cool since it suggested only about +1.8 per the graph. For tomorrow's 1 + 2, it is actually projecting about +1.9 or slightly warmer than the prior week based on the same graph. Let's see what tomorrow's NCEP release will show. Also, let's see how Cowan's graph looks about a week from now. With this region's inherent relatively high volatility (especially just after the sudden strong move being suggested), it could easily then show a lot warmer than it currently shows. Bottom line: I wouldn't read too much into this Cowan graph's 1 + 2 cooling as of yet.

http://www.tropicaltidbits.com/analysis/nino12.png

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I see that the Cowan Niño 1 + 2 has fallen from +2.3 to +0.9 in a mere six days and it is still falling fast! This could easily fall to near +0.5 based on its still steep drop. However, I do wonder about its accuracy. Compared to NCEP's +2.6 of last week, Cowan's graph was about 0.8C too cool since it suggested only about +1.8 per the graph. For tomorrow's 1 + 2, it is actually projecting about +1.9 or slightly warmer than the prior week based on the same graph. Let's see what tomorrow's NCEP release will show. Also, let's see how Cowan's graph looks about a week from now. With this region's inherent relatively high volatility (especially just after the sudden strong move being suggested), it could easily then show a lot warmer than it currently shows. Bottom line: I wouldn't read too much into this Cowan graph's 1 + 2 cooling as of yet.

http://www.tropicaltidbits.com/analysis/nino12.png

It seems that the Cowan figures have been outliers at times. Like you, I find its current numbers somewhat suspect. I'll look forward to NCEP's update.

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It seems that the Cowan figures have been outliers at times. Like you, I find its current numbers somewhat suspect. I'll look forward to NCEP's update.

Levi Cowans site seems to be having data issues as it shows different numbers from everyone else so maybe right now we should only use official ones until he can fix the issues

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^Could the too cool Cowan 1 + 2 have been due to persistent/extensive cloudiness there since it is satellite based? I don't follow the satellite photos there to even know if clouds have been dominant. I'm just wondering.

Anyway, it looks like it finally bottomed at around +0.63.

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From today's MEI update:

 

"The updated (April-May) MEI has risen by 0.61 standard deviations in one month to +1.57, for a high ranking above the 'strong' El Niño threshold (upper 10%ile). This is the highest MEI value in 17 years, surpassing the peak of the 2009-10 El Niño by a few 1/100. The current El Niño has ranked above the weak El Niño threshold for four months in a row, and above the strong threshold for two months running. If it were to remain above the strong threshold for just one more month, it would be the first strong El Niño event since 1997-98 with at least three months registering in the upper 10%ile. By this definition, six other El Niño events occurred since 1950: 1957-58, '65-66, '72-73, '82-83, '86-87, and '91-92, or just over once a decade.

 

Looking at the nearest 12 rankings (+5/-7) in this season, and excluding cases with declining April-May values compared to earlier in the year gives us six 'analogues' to ponder: 1957, 1987, 1993, 1997, 2002, and 2014 (all but 2014 are included in the MEI comparison figure of this section). Except for 2002-03, peak values of the remaining four events reached the strong threshold and maintained it from three months (1993) to 13 months (1997-98). None of the comparison figure cases dropped back to ENSO-neutral rankings before the end of the calendar year. Thus, if it were not for last year's unusual evolution, it would be safe to state that El Niño conditions are virtually guaranteed through 2015. Nevertheless, the odds for a substantial El Niño during the next six months appear better than since at least 2009.  

 

...El Niño went through a four-month 'dress rehearsal' last boreal summer, disappeared for two months, returned for two months, went back to an El Niño-flavored neutral status in January, but has steadily grown to its highest value in 17 years as of April-May 2015. If it stays above +1.2 for just one more month, it will have exceeded the upper decile threshold for three months running, thus joining the somewhat exclusive 'club' of strong events according to the MEI. Meanwhile, typical El Niño impacts will be supported by positive PDO conditions that have endured since January 2014, reaching record levels from December through February 2015."

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The current strengthening El Niño is certainly having a large impact on the MJO right now. The latest amplitude was the 10th highest on record for June. Previously, the 11 highest amplitudes occurred during June 1997. It will be interesting to see if the El Niño continues to have a large impact on the global weather patterns as it continues to evolve.

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Looking at the SOI outlook for June:

  Per the latest model consensus with an emphasis on the Euro, there is still no indication that the SOI is headed back to the strongly -SOI's that dominated most of May at least through ~6/16. So, as of now the projection for June 1-16 is for at most a modestly negative SOI. This raises the chance that June overall won't be a strongly -SOI month. IF that were to occur, it would represent a significant + diversion of this June's SOI from the solidly to strongly -SOI consensus of June for the nine analogs that I've found that were either (oncoming) 2nd year strong/super or standalone oncoming superstrong Nino's:

 

1997: -24.3

1987: -17.9

1982: -17.2

1972: -10.9

1940: -17.2

1905: -27.7

1896: -27.0

1888: -14.4

1877:   -7.0

 

 By the way, the July #'s were similar: -9.0, -17.3, -17.9, -17.3, -14.3,  -19.8,  -19.1, -15.5, -9.5

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Per the 0Z 6/10 Euro, there are finally signs suggesting at least a few days of strongly -SOI's. The SOI would fall rather sharply from 6/17 through around 6/20 though the SOI could then rebound soon afterward. We'll see.

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Per the 0Z 6/10 Euro, there are finally signs suggesting at least a few days of strongly -SOI's. The SOI would fall rather sharply from 6/17 through around 6/20 though the SOI could then rebound soon afterward. We'll see.

 

I wouldn't worry about the recent positive daily SOI too much.  Tahiti just so happened to fall under the northern edge of some persistent high pressure, while pressures have remained anomalously low to the north and east (i.e. closer to the Nino 1-4 regions). 

 

What will probably do more damage so to speak will be the anomalous easterly winds expected over the next week or so, although I think we should go back to more westerlies by week 2.  Either way, we're definitely due for another robust WWB similar to the one in early May if we are to continue along the path towards strong El Nino.

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ENSO Diagnostic Discussion, June 11.

 

l..... For the fall and early winter, the consensus of forecasters slightly favors a strong event (3-month values of the Niño-3.4 index +1.5°C or greater), relative to a weaker event. However, this prediction may vary in the months ahead as strength forecasts are the most challenging aspect of ENSO prediction. A moderate, weak, or even no El Niño remains possible, though at increasingly lesser odds. There is a greater than 90% chance that El Niño will continue through Northern Hemisphere fall 2015, and around an 85% chance it will last through the 2015- 16 winter.

 

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf

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 Although not currently updating with dailies, this weekend's SOI's are almost definitely fairly solid +'s. There will probably be a couple more days of +'s to follow. However, by 6/18-9, it looks to go to - per today's 0Z Euro. That same model also suggests that that might be the start of an extended -SOI period, quite possibly including some strong -'s by 6/24. So, where June ends up as a whole is still very much in the air. If it is going to end up solidly -, there would likely have to be a very strongly -SOI period the last week of this month to even make that possible. Otherwise, we're probably looking at anywhere from a modestly -SOI to near neutral for the full June SOI, which would diverge from the solid -SOI's for June for the analogs of either 2nd year strong to super Nino or standalone super Nino (see post #115 just above this). We'll see. The rest of this month will be quite interesting to follow.

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Today's 0Z Euro continues the suggestion of a strong -SOI 6/24 and suggests a very strong -SOI for 6/25. It also suggests that the remainder of June from then could easily be solidly to strongly in the -SOI's. So, the fate of June as a whole is still to be determined as there appears to be a strong push of -SOI's late. We'll see.

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