ENSO Updates (2007 thru 2023)

[cycloneye]

Look who is chimming in on the big WWB comming.

@philklotzbach
Westerly wind event underway strongest in magnitude in the central Pacific since 1997 according to NCEP Reanalysis.

[xtyphooncyclonex]

Probably unlike last year, the WWB is really taking into effect. 4 active tropical cyclones (named storms) along the equator with 3 in the Southern Hemisphere (Pam in the South WPAC; Nathan and Olywn in the Indian Australian Region) and 1 over the northern Hemisphere (Bavi over North WPAC) with potential of becoming a full-blown typhoon. Pam is quite likely, according to some global models, to become an extraordinarily powerful cyclone.

[cycloneye]

Interesting post at WU that I share for the S2K members to look at about ENSO,WWB etc.All I can say is this person knows plenty about this and has a bright future if he decides to go to the met carrier.

you should keep in mind the historical record we're working with here is short) the Australian Bureau of Meteorology identifies 10 -IOD events since 1958, the only -IOD they made note of which was coupled w/ a full-blown El Nino (under the new ONI definition (i.e. not old 1971-2000 climatology) was in 1958. There were other -IOD/+ENSO combos in 1992 & 1993, but no moderate-strong El Ninos, but that doesn't necessarily preclude one from transpiring... We'll have to wait & see how this robust -IOD responds to the seasonally phase locked, easterly propagating Wyrtki jets. On the other hand, the rather dramatic weakening of the upper tropsopheric TEJ (Tropical Easterly Jet, maintained by the meridional upper tropospheric thermal gradient between the Tibet anticyclone and the adjacent Indian Ocean) has weakened substantially due to the multidecadal & comparatively rapid warming of the northern Indian Ocean, favor lower frequency persistence of the -IOD & hence eastern hemisphere interference that has become a customary feature of most modern-day El Ninos...

The zonal extent of the TEJ underwent substantial contraction thru the 1980s, and the core of the TEJ continues to wither away, w/ a decrease in the U 150hpa wind of about 10 m/s since the 1950s, while the TEJ is actually beginning to zonally expand once again over Africa, in concert w/ a wetter African Sahel...




150mb U Wind since 2010, weakening of the TEJ continues...




Also, I'll mention (aside from aforementioned conflict between the North & South Pacific in their multidecadal +PDO states & potential E hem/IO interference w/ this upcoming El Nino once the favorable MJO equatorial symmetry abates as we progress further away from the equinox), the current +AO/NAM state is not conducive to a returning El Nino which once again, could be teleconnected thru modulation of the Pacific Jet, RWTs, etc. to the increasingly intrusive Indian Ocean?...




It certainly appears the Indian Ocean likely helped incubate the PV, especially earlier this past winter & late in the fall, & this IO forcing helped stunt significant wave/momentum driving/deposition onto the PV that was being imparted thanks the extreme SAI/SCE ...




Eventually the east-based El Nino won out, but even still, the weaker wavenumber 2 Upper Level VP signature remains intact...




Comparing the JFM SLP in first year El Ninos since 1900 that returned for at least a second year vs the top 10 first years w/ the most dramatic flip to a la nina (used 1971-2000 ONI climo) in the following winter, the SLP difference among these sets of years yields the correlated AO SLP pattern, thus highlighting the importance Northern Annular Mode as a primary determinant in the shelf life of an El Nino event.





Along w/ the other aforementioned unfavorable pre-conditions, it will be interesting to see how this El Nino handles this interference as the favorable intraseasonal/seasonal coupling to the downwelling KW, MJO, Weak Zonal SST gradient, etc. abates later this spring & summer, which in all likelihood may be enough to preclude a strong El Nino, and almost certainly will prevent the genesis of a "Super" El Nino as we observed in 1877-78, 1982-83, & 1997-98...

[Kingarabian]

So the WWB, if it arrives as strong as advertised - should trigger a full blown Nino?

Last year we had a strong WWB + a warm pool that didn't surface yet, but when it did, it was cooled by Easterlies.

I guess with sufficient warm waters now, this WWB could push Nino into moderate strength. Depends on what happens after the WWB passes.

I also think that the really warm PDO was the main reason that allowed the El-Nino to survive.

[OURAGAN]

For the moment nino 1+2 has cooled

[img]Image issue du site Web http://guadeloupe.edf.com/fichiers/fcke ... r-2015.jpg[/img]

[OURAGAN]

[TropicalAnalystwx13]

So the WWB, if it arrives as strong as advertised - should trigger a full blown Nino?

Last year we had a strong WWB + a warm pool that didn't surface yet, but when it did, it was cooled by Easterlies.

I guess with sufficient warm waters now, this WWB could push Nino into moderate strength. Depends on what happens after the WWB passes.

I also think that the really warm PDO was the main reason that allowed the El-Nino to survive.

Westerly wind bursts can lead to the development of a downwelling kelvin wave if persist enough. These waves allow subsurface waters to anomalously warm, replacing cooler anomalies as the wave and warm pool move eastward. 2014 started off with a historic subsurface warm pool, but it faded away during the summer. Keep in mind that the typical wind component across the equatorial Pacific is easterly; El Niño just represents a reversal of those winds. A lack of continued westerly winds in summer 2014 allowed the common easterly winds to reestablish themselves, keeping us Neutral for the next several months.

[Ntxw]

Another possible WWB coming the second half of March. This one progressing further east. The eastern Pacific basin is likely to experience weaker trades that have been cooling the waters there as well. Notice the lighter yellows coming on east of 120W. That is Nino 3 and Nino 1+2 likely switching to a warming wind as well.

[cycloneye]

After a few months in negative (Around -60) ESPI is now in positive and that is good for El Nino prospects.The rainfall in the equator or lack of is another piece of the big ENSO puzzle

[cycloneye]

The warm westerlies have propagated more eastward now.Let's see what happens in the next few weeks.

[cycloneye]

We heard this before right? ECMWF March forecast is for a strong El Nino for the Summer and Fall but EC has busted in the past so we will see.

[cycloneye]

Nino 3.4 stays at +0.5C on the weekly CPC update of 3/16/15.

http://www.cpc.noaa.gov/products/analys ... ts-web.pdf

[wxman57]

We heard this before right? ECMWF March forecast is for a strong El Nino for the Summer and Fall but EC has busted in the past so we will see.

http://i.imgur.com/FE99FCi.gif

For the past 2 seasons, the verification was pretty bad. It was great in 2012, but again the EC predicted temps way too warm in 2011. That's 3 out of 4 years where the actual temps trended toward the cooler EC ensemble members. Based on what I'm seeing now, I'd say that the most likely Nino 3.4 values this summer would be in the +.8C to +1.0C range, or a weak to moderate El Nino.

2011:


2012:


2013:


2014:


My 2015 Prediction? (black dashed line):

[Ntxw]

MJO has gone nuts. Highest deviation from normal ever (single real time). SOI is crashing with it.

[dexterlabio]

^is there latest MJO graphic available?

[wxman57]

^is there latest MJO graphic available?

Latest MJO charts are here:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

Raw RMM1 & RMM2 data are here. Formula for calculating the total value is (RMM1^2 + RMM2^2)^0.5, which is basically the square root of the sum of the squared RMM1 + RMM2 values:

http://cawcr.gov.au/staff/mwheeler/maproom/RMM/RMM1RMM2.74toRealtime.txt

[cycloneye]

The Aussies update of 3/17/15.

Tropical cyclone activity may lead to further ocean warming

Issued on 17 March 2015 | Product Code IDCKGEWW00

The past fortnight has seen unusual conditions in the tropical Pacific, which may increase the chance of El Niño in 2015.

In the western Pacific, severe tropical cyclone Pam and tropical storm Bavi* straddled the equator, producing one of the strongest reversals in the trade winds in recent years. This change is expected to increase the already warm sub-surface temperatures currently observed in the tropical Pacific Ocean, which may in turn raise tropical Pacific Ocean surface temperatures in the coming months. However, it remains too early to say whether the reversal in the trade winds is a short term fluctuation or the beginning of a sustained trend.

International models surveyed by the Bureau have strengthened their outlooks for the likelihood of El Niño, with all eight models suggesting ocean temperatures will exceed El Niño thresholds by mid-year. However, model outlooks spanning the traditional ENSO transition period, February to May, generally have lower accuracy than outlooks made at other times of year.

The Bureau's ENSO Tracker remains at El Niño WATCH. This is due to a combination of warmer-than-average sub-surface temperatures in the tropical Pacific Ocean and models indicating that central and eastern tropical Pacific will warm to El Niño thresholds by mid-year. An El Niño WATCH indicates that there is about a 50% chance of El Niño forming in 2015—double the normal likelihood of an event.

El Niño is often associated with below-average winter–spring rainfall over eastern Australia and above-average daytime temperatures over the southern half of Australia.

http://www.bom.gov.au/climate/enso/#tabs=Overview

[Ptarmigan]

The Aussies update of 3/17/15.

Tropical cyclone activity may lead to further ocean warming

Issued on 17 March 2015 | Product Code IDCKGEWW00

The past fortnight has seen unusual conditions in the tropical Pacific, which may increase the chance of El Niño in 2015.

In the western Pacific, severe tropical cyclone Pam and tropical storm Bavi* straddled the equator, producing one of the strongest reversals in the trade winds in recent years. This change is expected to increase the already warm sub-surface temperatures currently observed in the tropical Pacific Ocean, which may in turn raise tropical Pacific Ocean surface temperatures in the coming months. However, it remains too early to say whether the reversal in the trade winds is a short term fluctuation or the beginning of a sustained trend.

International models surveyed by the Bureau have strengthened their outlooks for the likelihood of El Niño, with all eight models suggesting ocean temperatures will exceed El Niño thresholds by mid-year. However, model outlooks spanning the traditional ENSO transition period, February to May, generally have lower accuracy than outlooks made at other times of year.

The Bureau's ENSO Tracker remains at El Niño WATCH. This is due to a combination of warmer-than-average sub-surface temperatures in the tropical Pacific Ocean and models indicating that central and eastern tropical Pacific will warm to El Niño thresholds by mid-year. An El Niño WATCH indicates that there is about a 50% chance of El Niño forming in 2015—double the normal likelihood of an event.

El Niño is often associated with below-average winter–spring rainfall over eastern Australia and above-average daytime temperatures over the southern half of Australia.

http://www.bom.gov.au/climate/enso/#tabs=Overview

I notice most of the forecast models have strong El Nino by August. This could be interesting.

[dexterlabio]

1997 had its first ONI value greater than 0.5 during AMJ period..but I'm wondering when was El Nino officially declared that year?

[xtyphooncyclonex]

1997 had its first ONI value greater than 0.5 during AMJ period..but I'm wondering when was El Nino officially declared that year?

I heard that it was declared May, when it had already become a moderate Niño..