GaWx

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!

Tulsa, OK, was 84.3 F in Sep ‘26, which was in addition to being 10.1 warmer than the longterm Sep mean: - 2.4 warmer than its 2nd warmest Sep - 1.4 warmer than its longterm mean for July - warmer than 69% of Julys, 74% of Augusts, and 98% of Junes on record (records back to 1905) @donsutherland1

Follow-up: As expected based on the model consensus having significantly warmer 2m maps on Sep 30th vs Sep 29th at 80N+, the DMI warmed notably yesterday (>1C) vs Sep 29th as it rose to the blue line (mean for 1958-2002). It should warm further tomorrow:

12Z UKMET: Fay starts off deceased but she gets revived once again (on Friday) and like 2 runs ago later becomes a TS: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 60 HOURS FORECAST POSITION AT T+ 60 : 27.3N 60.5W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 03.10.2026 60 27.3N 60.5W 1014 27 1200UTC 03.10.2026 72 29.3N 60.6W 1013 28 0000UTC 04.10.2026 84 31.8N 60.1W 1012 30 1200UTC 04.10.2026 96 34.0N 58.9W 1012 30 0000UTC 05.10.2026 108 35.6N 57.1W 1011 29 1200UTC 05.10.2026 120 37.5N 55.3W 1009 30 0000UTC 06.10.2026 132 40.2N 53.3W 1004 33 1200UTC 06.10.2026 144 44.7N 49.2W 996 41 0000UTC 07.10.2026 156 51.2N 44.3W 992 43 1200UTC 07.10.2026 168 CEASED TRACKING @jconsor

As I said, I’ve been following model initializations of 2m at 80+ N. They were colder than climo most of late May-early Aug. Check out those of the Euro for yesterday: clearly solidly BN vs 1981-2010 for 80N+ on Sep 29th (associated with a storm)(they were also quite cold going back to Sep 23rd by the way), which may actually be cold enough to support the ~2C colder than the 1958-2002 mean shown on the newest DMI graph: Here’s the Euro forecast for Oct 2nd, which shows notable warming as the storm moves S into Siberia. This is why I’m expecting warming on the DMI graphs by then: @so_whats_happening@OSUmetstud