GaWx

The NOAA ERSSTv6 Sep PDO was -0.74: -As expected based on WCS, this was less negative than Aug’s -1.12 -This is the least neg Sep since 2019’s +0.44. -2023 Sep was way down at -2.52! -This is the 3rd month in a row that NOAA came in less negative than avg of WCS dailies, which was ~-1.0 in Sep - The NOAA August PDO had come in at -1.12 vs the WCS avg of ~-1.55. https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/v6/index/ersst.v6.pdo.dat

Here I got rain since 12:45PM-1:30 moving NE with some of it very heavy. This is in addition to a quick shower this morning and moderate rain (few tenths) late yest. afternoon from popups. It appears I’dreceived 1.5”+ from all of this with most of it just since 12:45PM. This compares to ~2.55” for all of Sep! Update at 5: been getting additional mod to heavy rain since 4:45. I’m now likely at 2”+ since yest.

We agree that the absolute 3.4 temp has been blowing away its record since summer on OISST. But a portion of that difference from prior records is obviously due to the globe being near its warmest on record: -Avg trop ocean warming since 1997 is ~0.6C. So, without any of that warming, 2026 OISST would still be warmer going back to Sep 1st. But the diff would be ~0.6 smaller. -Avg warming since 1982 ~~0.8C. So, it would still be warmer than 82 w/o the GW since then but would be ~0.8 smaller diff. -It has warmed ~0.3C since ‘15. So, even after taking into acct GW, it would still be blowing away ‘15. -It is pulverizing ‘23 as that was a much weaker Nino at this point vs the other 3 and there’s been some GW since then. -Also, keep in mind that cyclonicwx’s OISST graph has been ~0.4 warmer than NOAA’s OISST the last 2 months. They used to be within ~0.1 apart on avg. I don’t know why, but it’s possible Alex’s OISST has been skewed a few tenths higher due to a bug for all I know. -Even after taking into account both a possible bug in Alex’s graph and GW, ‘26 looks like it would still be at a record in 3.4.

1. The concept of RONI applies to all ENSO. 2. ONI is a good measure of the combo of GW and ENSO. RONI is a good measure of ENSO, alone. 3. NOAA officially currently has 1972-3 at +2.0.

As the globe warms, the threshold for the SST becoming much more favorable for convection warms: Significant Increase in Sea Surface Temperature at the Genesis of Tropical Mesoscale Convective Systems “We show that this threshold (SSTG) has undergone a significant warming trend at a rate of ∼0.2°C per decade. The SSTG shows a remarkable correspondence with the tropical mean SST and upper-tropospheric temperature on interannual and longer timescales.” “The development of tropical ocean showers and thunderstorms requires a warm ocean surface as an energy source fueling the storm.” ”Using satellite observations and a high-resolution global climate model, we show that this threshold has undergone a significant warming trend during the past several decades and will continue to increase in the future. This warming trend is closely related to the changes in the tropical mean SST. A constant relationship between the SST threshold and upper-tropospheric temperature is found in both the current climate and a warming climate, which corroborates the argument that tropospheric temperatures in the tropics approximately follow a moist adiabatic adjustment.” https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101950

You said in your earlier post that I responded to: “It was a+2.1 event up until a few years ago before the CPC dropped it to +1.8. So until very recently it was rated as a lower end super.” 1. The CPC officially now has 72-3 at +2.0, not +1.8, as I showed, because ONI hasn’t been official since Feb. 2. You said, “With an event as extreme as this RONI can make the event seem weaker than it actually is.” No, it’s not RONI making the event seem weaker. It’s ONI making the current Nino seem stronger than it really is due to GW. That’s the reason the RONI exists. ONI isn’t per NOAA and BoM the absolute strength of the 26 Nino, itself, because that exaggerates the strength due to adding the increasing warming from GW to the warming from El Niño, itself. The warming from El Niño, itself, is what RONI measures. I’ll use a hypothetical example to illustrate better: -Say that the avg worldwide tropical ocean 30 year SSTa is at +1.0 vs its prior 30 year avg. Now say that 3.4 is also at +1.0 vs its own 30 yr avg. Per ONI it’s a +1.0 Nino. But per RONI it’s at 0.0/neutral because it’s measuring the contrast of the 3.4 anom vs the anomaly of the tropical waters. NOAA and BoM at the least have determined that +1.0 is deceptively high in this example because 3.4 is up to +1.0 due to GW, not because of El Niño. Measuring the true strength of ENSO means measuring the contrast with surrounding tropical waters. If 3.4 and avg tropical waters are both at +1.0c there’s essentially no contrast (no relatively warm tongue in 3.4) and thus no Nino. A contrast is needed to have a Nino (or a Niña) per the official RONI. With no contrast like in this example it is neutral. @mitchnick

26 is also notably colder than 23 in the Arctic.

Even throwing in the towel just based on ENSO, alone, would seem to be awfully bold.

I know it is hard to accept because of Fay’s tenacity, but the 0Z UKMET actually dropped her coming back to being a TC. Poor Fay

The CPC has 1972-3 peaking at +2.0 in its most up to date RONI table linked just below. Since RONI is the official way of classifying (and has been since Feb), that’s the current CPC official peak for 1972-3 rather than +1.8: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/ More on the transition of CPC from ONI to RONI for official classification of ENSO (this was released in Feb 2026): https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/announcement.php From the link above: “The Climate Prediction Center is making the shift to use the Relative Oceanic Niño Index (RONI) to better designate past events and predict future ENSO.” ——————— The table at the link below, which is to the most up to date ONI, has 1972-3 peaking at +1.8. But ONI hasn’t been the official way for CPC to classify since Feb. At the top it says this: This page will continue to be updated by the 5th of each month, but per NWS Public Information Statement 26-05, the Relative Oceanic Niño index (RONI) is used for official monitoring and prediction of the El Niño-Southern Oscillation (ENSO) phenomenon. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/oni/v6/ @Maestrobjwa

This like another map I saw this morning shows that I’d get within just the next few days at least as much as I got in all of pretty dry Sept., which was ~2.55”. So, I hope it verifies pretty closely for MBY. In reality due to the showery nature of some of this producing isolated heavy amounts, I realize there will likely be significant variations in totals within pretty short distances though.

I agree with most that a record strong RONI is likely at this point. But NOAA is ~0.4 cooler than this fwiw (low +2s). So, it very likely won’t get nearly as warm as some models, like the BoA (still way up near +3.8) are showing. Regardless, the strongest anomalies are going to continue to be in 1+2 and 3. This is now the most E based on record by a good margin over 1997, and that’s looking to continue down the road.

1. Technically FYI, “super” is not an official category for NOAA. I think they call those with RONI max of +2.0+ “very strong” or something similar. But here we including myself usually call them “super”. 2. 72-3 barely qualifies as “super” or “very strong” per the RONI table: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/

17.4 (1983) Going back all the way to 1851, only 3 had lower ACE than 1983 and all of them could have been higher in reality due to being way before the satellite era: 1914, 1925, 1907 https://en.wikipedia.org/wiki/Accumulated_cyclone_energy

I ended up getting only ~2.55” of rainfall in Sept, which is well below the longterm average of >4.5”. The upcoming progged significant rainfall in early Oct here would be most welcomed!