ENSO Updates (2007 thru 2023)

[NotSparta]

https://twitter.com/MJVentrice/status/1239871449185345538

https://twitter.com/PaulRoundy1/status/1239872743773999105

Is Ventrice saying that enhanced trades simply warm the WPAC or they could trigger downwelling Kelvin waves @ the subsurface?

Sounds like he's talking about the usual warming of the WPAC and downwelling as enhanced trades pile water into the IPWP, as is usual with -ENSO events

[StruThiO]

JISAO data for the PDO can be found here. https://oceanview.pfeg.noaa.gov/erddap/tabledap/cciea_OC_PDO.htmlTable?time,PDO

The PDO value for February fell to -0.68, the lowest value since October 2013.

[Kingarabian]

Tonight's 00z Euro has the SOI negative for the next 10 days and this means March will likely have a negative SOI.

[cycloneye]

 https://twitter.com/climatesociety/status/1240708868881014784

[Kingarabian]

The subsurface in terms of oceanic Kelvin wave configuration is not too far off from 2017 at this point in time. Both had downwelling kelvin wave's layered over a shallow thermocline although currently, there's certainly more OHC compared to 2017.


2017 had successive strong trade bursts over the dateline throughout spring and into the summer that helped ensure cool-neutral for the summer and La Nina in the fall. This upcoming trade burst is crucial and will have to play a large role in dissipating the present warm pool. Also important: despite it being 10 days out, models are in surprisingly good agreement that the trades will weaken over the dateline by March 30th and the GFS actually has a decent WWB in place by the first week of April (the gif below is a 10-16 day forecast so it can easily change).


Nino 3.4 continues to be over or at +0.5C and I think Monday's update will keep Nino 3.4 @ +0.5C. SST's take a week or more to respond to wind activity, so it's possible that the following Monday update keeps Nino 3.4 @ or above +0.5C... which means that it's possible the CPC will be dealing with a 4th tri-monthly in a row of +0.5C or higher.

[cycloneye]

 https://twitter.com/WxTca/status/1241451385272578050

[cycloneye]

 https://twitter.com/NightriderFL/status/1241704313514328064

[WeatherEmperor]

For today's update the Nino regions stay warm with no cooling taking place as some models project

1+2 is at + 0.5c
3 is at +0.4c
3.4 is up to +0.8c
4 is at +1.4c


Sent from my iPhone using Tapatalk

[Kingarabian]

For today's update the Nino regions stay warm with no cooling taking place as some models project

1+2 is at + 0.5c
3 is at +0.4c
3.4 is up to +0.8c
4 is at +1.4c


Sent from my iPhone using Tapatalk

The trade burst kicks off today and it will continue for the next 5 days before they relax again. The effects wont be felt until a week or so from now and while its possible that surface temperatures could cool because of it, this trade bursts main effect will be below the surface. It should stop the supply of warm waters from the WPAC feeding into this persistent downwelling Kelvin wave (warm pool) and allow for cooler anomalies to develop and take over. This should be the start of the transition towards cool-neutral although models are insisting of a 30-45 day period of relaxed trades over the dateline which could complicate things.

Notice how even the latest subsurface update still shows a stream of warm anomalies which is causing the thermocline to remain suppressed.


CFS 90 day:

[cycloneye]

 https://twitter.com/MJVentrice/status/1242246481031069698

[cycloneye]

 https://twitter.com/MJVentrice/status/1242249141662765057

[StruThiO]

[AnnularCane]

What does that last one mean?

[NotSparta]

:uarrow: What does that last one mean?

The enhanced convection around the dateline that usually appears during an El Niño event has broken down, which means it'll be more difficult to set off WWBs

[Kingarabian]

:uarrow: What does that last one mean?

What Sparta said. And at the upper levels, when there's enhanced convection, there's usually rising motion associated with it and models for the most part detect that as -VP anomalies. When these -VP anomalies are situated over an area for an extended period of time (usually 3 months) they also label it as a "standing wave". During El Nino this standing wave is typically over or near the dateline.

Here is the low pass from the CFS showing it has broke down in March:


@ the upper levels from the CFS:

[Kingarabian]

Per CDAS this has been the first time since late October that cloud coverage was below normal over or near the dateline:


Also: Levi Cowan's 850mb wind maps @ Tropicaltidbits.com show that the GFS, Euro, and CMC are in near 100% agreement that at the least there will be below average trades over the dateline and CPAC during the first week of April, due to a passing equitorial rossby wave.

[Shell Mound]

OT: Isn’t the weak MJO signal (amplitude) around the first week of April typically a precursor, ceteris paribus, to possible La Niña development later on? Both the GFS and ECMWF ensembles are in strong agreement that the MJO signal should weaken as we enter the first week of April. Since early February, the overall amplitude of the MJO appears to have been the weakest for this timeframe since 2011. (Of course, 2011-12 marked a double-dip Niña, as it followed the Niña of 2010-11—the latter a strong episode, the former moderate.) Overall, the amplitude is quite similar to that for the same timeframe in 2010, which transitioned out of a strong Niño. So the fact that we are seeing a response similar to that which preceded the last strong Niña, despite coming out of a weak (borderline) Niño, is at least a bit interesting.

[cycloneye]

 https://twitter.com/AndyHazelton/status/1243606717851734017

[Kingarabian]

https://twitter.com/AndyHazelton/status/1243606717851734017

I think 2017 @ the subsurface is a closer analog:


How long it takes ENSO to switch to cool-neutral before the summer is key for La Nina formation by ASO.

Now the short term debate is what happens if ONI hits 5 straight monthlies of +0.5C? Because It's looking that the final week of March will have Nino 3.4 above +0.5C and there's a strong chance that JFM comes in @ +0.5C... which would make it 4 straight monthlies. Some modeling shows there's enough OHC for Nino 3.4 to be above +0.5C in April. Interesting to see what the CPC does here.

[Kingarabian]

OT: Isn’t the weak MJO signal (amplitude) around the first week of April typically a precursor, ceteris paribus, to possible La Niña development later on? Both the GFS and ECMWF ensembles are in strong agreement that the MJO signal should weaken as we enter the first week of April. Since early February, the overall amplitude of the MJO appears to have been the weakest for this timeframe since 2011. (Of course, 2011-12 marked a double-dip Niña, as it followed the Niña of 2010-11—the latter a strong episode, the former moderate.) Overall, the amplitude is quite similar to that for the same timeframe in 2010, which transitioned out of a strong Niño. So the fact that we are seeing a response similar to that which preceded the last strong Niña, despite coming out of a weak (borderline) Niño, is at least a bit interesting.

It's usually the case that for an El Nino to develop by ASO if there's stronger MJO amplitude over the Pacific during the months of spring. There are some exceptions as we saw in 2006 and 2018, those years had weak MJO amplitude's during April and May. 2002 had the MJO mainly over the IO during April, only for the MJO to go strong over the Pacific in May and that resulted in an El Nino. So there are certainly some exceptions and we'll have to wait till May to see if La Nina is possible or not for ASO.