griteater

Number of -NAO Winters during El Nino since 1900 Weak El Nino: 5/14 Moderate El Nino: 8/16 Strong El Nino: 6/9 Super El Nino: 0/3

500mb composites here of all Strong El Ninos, Pre and Post 1950 -NAO is more common during Strong El Nino than any other ENSO phase

TAO images for July 13 and July 23

We did have some westerly wind anomalies working into the Dateline in recent days, but overall, the MJO signal on these Euro Weekly plots continues to weaken when looking ahead

This is from the Institute of the Sea of Peru ("summer of 2024" is our upcoming winter)... July 21, 2023 The ENFEN Multisectoral Commission maintains the status of "Coastal El Niño Alert", as it is expected that coastal El Niño (Niño 1+2 region) will continue until the summer of 2024, as a consequence of the high probability of El Niño development in the central Pacific. The maximum monthly anomalous warming would be reached in July. For the remainder of the year, anomalous warm conditions would decrease from strong to moderate intensity. By summer 2024, the most likely magnitudes of coastal El Niño would be between weak (40%) and moderate (35%). In the central Pacific (Niño 3.4 region), according to ENFEN's expert judgment, based on observed data, as well as forecasts derived from international climate models to date, anomalous warming is more likely to continue to increase within moderate condition until the end of the year. By summer 2024, the most likely magnitude for El Niño in the central Pacific would be between weak (43%) and moderate (38%). It should be noted that, although long-term numerical models coincide in indicating the development of an El Niño event of strong magnitude (on average) by the end of the year, what has been observed to date only shows a slight coupling between the ocean and the atmosphere. Official Communiqué ENFEN N° 11-2023 - Reports and publications - Instituto del Mar del Perú - Plataforma del Estado Peruano (www.gob.pe)

Here is the latest 30-day OLR/VP plot from JMA showing a sort of 2 wave or 4 cell pattern of -VP uplift extending from the dateline and back west to Indonesia, and also in the far E Pac / Atlantic....with +VP subsidence in E Africa / W Indian Ocean and C Pac. In comparison, the same dates in 2015 show what a Super El Nino looks like...strong 1 wave / 2 cell pattern of +VP subsidence in the Eastern Hemisphere centered over the Indian Ocean and -VP uplift in the Western Hemisphere centered over the East Pacific

I'd say 2 going themes with this El Nino over the past few months are: 1) The East Based nature of the event thus far, and 2) The models consistently over predicting westerly wind anomalies working east out into and past the dateline. Plenty of time for that to change, but this is keeping Nino 3.4 SST anomalies in check at the moment, and no guarantees this doesn't continue to be an issue for big warming. Here are the Euro Weekly runs from July 17 and July 21 (today). Can see here the weakened signal for westerly wind anomalies (in yellow / orange) with these 2 runs as we close out July.

The June 17th run of the Australian Bureau of Meteorology ENSO model predicted +1.8 for Nino 3.4, averaged for the month of July. Yet here we are for July 1 to 21

Same trend but for 7-day VP

Loop of last 5 runs of the EPS shows a weakening trend of the westerly wind anomalies trying to kick out into the Equatorial Central Pacific.

There is an Extended version of the MEI which goes back to 1871 Extended Multivariate ENSO Index: NOAA Physical Sciences Laboratory MEI.ext timeseries from Dec/Jan 1871 through Nov/Dec 2005 (noaa.gov) "Here we attempt to create a reliable ENSO index for much of the historical record by basing the extended Multivariate ENSO Index (MEI.ext) on the two main observed variables over the tropical Pacific that have been reconstructed by the Hadley Centre back to 1871. These two variables are: sea-level pressure (P; details in Allan and Ansell, 2006), and sea surface temperature (S; details in Rayner et al., 2006)."

I certainly didn’t think this strong eastern warming would hang on like it has in the absence of robust westerly wind anomalies and warming arriving from the west

From Weekly NOAA CPC MJO Update

As the old saying goes, “Fool me once, shame on you. Fool me twice, shame on me”

With respect to the MJO, I think 'both' can be true. The typical calculation of the MJO using RMM includes: 1) low level zonal wind anomalies (850mb), 2) upper level zonal wind anomalies (200mb), and 3) tropical convection (OLR). The stronger and more in phase each of these variables are, the higher the MJO amplitude will be. In these cases of higher MJO amplitude, we should expect the MJO to impart a greater impact on SST warming & cooling (depending on MJO phase) in the ENSO regions. In cases where the MJO is out of phase with the 3 components, you are going to have lower MJO amplitude numbers; however, it's still possible in these cases to have +850mb wind anomalies and -SOI that warm the ENSO SSTs. The current EPS and GEPS are making a move toward -SOI and +850 wind anomalies moving across the dateline which would likely lead to western ENSO region warming

In terms of betting on outcomes, it also depends on the details around what is considered strong / super etc. Does the +2.0C value mean daily, weekly, monthly, one tri-monthly, multiple tri-monthlies? There are varying definitions used of course. What I am personally currently using for the definition is looking at 3 data sets: 1) CPC ONI, 2) CPC RONI, and 3) EWebber ENSO ENS ONI. And if at least 2 of the 3 data sets classify it as Super Nino, then I go with it being a Super Nino. In terms of classifying it as, say, Strong vs. Super, I average the top 3 tri-monthly ONI values for the data set during the SON (Sep/Oct/Nov) to JFM (Jan/Feb/Mar) period. For example, if the top 3 tri-monthly values during that timeframe are 2.0/2.0/1.8, that would be a Strong Nino for that dataset....if 2.2/2.0/1.9, that would be a Super Nino for that dataset Prior to 1950, there is only one dataset, the EWebber ENSO ENS ONI

^ Yeah that link for the 20th Century Reanalysis data goes back to 1836 but ends in 2015 These 2 links (first for monthly data, and the second for daily data) begin in 1948 and stay current (latest month / latest day): Monthly/Seasonal Composites: NOAA Physical Sciences Laboratory Daily Climate Composites: NOAA Physical Sciences Laboratory And this link has a larger directory of these NOAA reanalysis pages (including the 2 above): Climate Plotting and Analysis Tools: NOAA Physical Sciences Laboratory

Out of interest we tend to scour thru the latest data with ENSO in here on a daily to weekly basis, but it is best to view ENSO's evolution on a multi-month basis (at least 2 months, but 3 to 4 months is better), particularly with OLR and VP data due to there being multiple elements that can affect the output (i.e. higher frequency elements like faster moving convectively coupled kelvin waves and the MJO <vs> the lower frequency impact of ENSO). Below are some reanalysis maps of OLR comparing May-June data for this year with prior El Nino cases back to 1980. I used OLR anomalies instead of OLR mean values. Note: OLR and VP data are typically considered unreliable prior to 1980 due to the fact that it is measured via satellite data which lacked the needed global coverage and robust capabilities back then (that is my understanding anyway). Here are the May-June OLR anomalies from the oncoming Super and Strong El Ninos since 1980. Negative anomalies are present along the equator over much of the Pacific, centered strongest in the 150W to 110W region. Positive anomalies are present over the Maritime Continent. Here are the May-June OLR anomalies from the oncoming Moderate El Ninos since 1980. Negative anomalies are present along the equator over the West and Central Pacific, centered strongest in the 140W to 160W region. Positive anomalies are present over the Maritime Continent. but on the S Hemisphere side, and in the East Pacific. Lastly, here are the May-June OLR anomalies for this year. Negative anomalies are present along the equator from the Maritime Continent to the Central Pacific. Positive anomalies are present in the East Pacific. So, in comparing this year with the prior year cases, we can see that the OLR is a bit farther west, especially compared to the prior Super Ninos.

I suspect we will see a sharp rise or 2 in 3.4 warming over the late summer to early winter period, but think we will end up classifying this as a strong Nino and not Super in the end. I’m more up in the air with the Nino base. Conventional wisdom says this will spread out more basin wide thru winter, but that’s not a guarantee based on a few prior cases and the Euro seasonal is stubborn to hang onto east based SSTs into winter. Regardless, nearly all seasonal modeling up to this point wants to hang the -VP back west

I just can’t figure out the source for such passion over trying to control what is discussed in here. Why get so fired up about others discussing how ENSO may impact the winter / or may impact the hurricane season. I guess it’s either due to a hatred for cold and snow or a pleasure in trolling others who are looking for a certain outcome (best guess is the latter, but I really don’t know…and more importantly, just don’t understand or relate to the concept of it)

I don’t know, I don’t see any harm in discussing how ENSO will impact the weather, whether that’s the hurricane season, or fall, or winter. That’s the whole point of having weather boards…and the vast majority of interest on weather boards is associated with winter weather. I don’t see anyone in here stating X or Y is definitely going to happen. It’s just discussion born from interest. No harm

That -VP is well west there. Here is a VP composite of Dec-Feb for 1987, 2003, and 2010

ENSO 1+2 has risen to its highest value to date on the UK OSTIA data (+3.07). There are some ongoing westerly wind anomalies in the E Pac so we may see some more warming in that region. ENSO questions as we move into Fall and Winter: 1) Will the E Pac SST warmth hang on thru winter? 2) How warm does NIno 3.4 get late fall into winter? 3) Will we see a strongly positive +IOD in the fall / or only slightly positive? 4) How will 1, 2, and 3 affect the location and strength of the low frequency Walker cell uplift & subsidence regions and associated convection?

HM is Anthony Masiello (Twitter). He used to post on AmWx as HM back in the day. There’s a side story as to why he was ‘HM’ on here, but I don’t recall the details behind that

The CFS will tend to ‘over-react’ to the current system state. If weakened trade winds are ongoing/forecasted, it will over-inflate upcoming SST warming. Conversely, if strengthened trade winds are ongoing/forecasted, it will over-inflate upcoming SST cooling