GaWx

-It is interesting due to its uniqueness though the PDO will probably rise significantly by winter. -These El Niño winters didn’t have a net RNA despite a net -PDO: 2018-9, 2006-7, 2004-5, 1994-5, 1972-3, and 1953-4 -These -PDO El Niño winters did have a RNA dominating: 1968-9, 1965-6, and 1951-2.

-True. How significant is it that the current sharp turnaround is occurring after a triple Niña vs after either a double or single Niña like 1972 and 1965? -The closest I can find to a strong Nino immediately following a triple Niña is the 1911-2 Nino, which peaked high end moderate (+1.4 ONI) after a triple Nina per this: https://www.webberweather.com/ensemble-oceanic-nino-index.html

Regarding turnaround within the same year, what about 1965 and 1972? They’re comparable at this point in the year. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

There are periods of both RNA and PNA during a typical winter. But the combo of it being El Niño instead of La Niña and how much cooler is the WPac N of Australia vs one year ago keeps me confident that a RNA won’t dominate. The last El Niño with a RNA dominating is way back in 1968-9. That means that there have been a whopping 18 El Niños in a row with either a dominant PNA (15 of the 18) or neutral (the other 3 of the 18): https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

Thanks mainly to a major SSW of 2/16/23 along with a second 10 mb wind reversal/warming 2/27/23 and also considering the typical ~2 weeks it takes for strat weakening to work its way well down into the troposphere, the NAO went from the +1.25 of Jan and +0.92 of Feb to -1.11 of Mar and -0.63 of Apr. That resulted in the SE US during mid Mar the coldest period since January. The main reason there was an even longer than normal lag from SSW to colder E US along with a shorter than average duration of cold was a strong RNA late Feb-Mar, which partially countered the effects of the strong -NAO.

One very good way is to look at the SOI. You don’t get a 56+ day -SOI streak when not in El Niño: Longest -SOI streaks in days since June 1991: 100: Days 3-102 of 1998 72: Days 195-266 of 1997 66: Days 248-313 of 2015 56: Days 232-287 of 2023 and still going 55: Days 191-245 of 2015 46: Days 268-313 of 1997 46: Days 6-51 of 2010 43: Days 175-217 of 1994 https://data.longpaddock.qld.gov.au/SeasonalClimateOutlook/SouthernOscillationIndex/SOIDataFiles/DailySOI1887-1989Base.txt All 8 40+ day streaks since June 1991 have been during El Niño.

Wasn’t a lot of the W 1/2 of the US snowy? But much of the E US was the opposite. Maybe it came in as a wash for the lower 48 averaged out?? Or did the AN snow anomalies out west outweigh the E US BN anomalies? If it was a wash, the Euro over predicted.

Also, note that it predicted last winter to be the 10th snowiest of the 44. Was it that snowy across the lower 48? Anyone know?

12Z UKMET for 94L has TS getting to 100 miles N of N Leewards moving NW: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 96 HOURS FORECAST POSITION AT T+ 96 : 12.1N 44.5W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 17.10.2023 96 12.1N 44.5W 1009 30 0000UTC 18.10.2023 108 12.3N 47.5W 1007 34 1200UTC 18.10.2023 120 13.0N 50.6W 1006 42 0000UTC 19.10.2023 132 13.9N 53.4W 1003 48 1200UTC 19.10.2023 144 15.3N 55.8W 1000 49 0000UTC 20.10.2023 156 17.0N 58.9W 997 47 1200UTC 20.10.2023 168 18.8N 61.6W 995 44

I’m guessing that Australia’s BoM and NOAA are using tables based on different calculations. And then the link at the tweet you quoted even says this, which doesn’t at all agree with either one: https://www.weatherzone.com.au/news/positive-iod-keeps-getting-stronger/1554561 “According to monthly IOD data from the Bureau of Meteorology, 2019 was the strongest positive IOD on record. However, some other datasets suggest that it may have been rivalled by 2017.” Looking at both the graph you showed as well as the table I’ve been using, 2017 is nowhere close to 2019 and 1997.

That uses a different calculation of DMI for some unknown reason and thus it doesn’t jibe with the table I quoted, which comes from here: https://psl.noaa.gov/gcos_wgsp/Timeseries/DMI/

Why is 2019 being called the current record strongest IOD event when the following link’s monthly IOD table says that November of 1997’s +1.279 was much stronger than October of 2019’s +0.964? I don’t get it. Please explain. 1997 -0.110 0.079 0.043 0.054 0.025 0.082 0.447 0.634 0.771 0.873 1.279 0.863 2019 0.387 0.416 0.224 0.258 0.539 0.605 0.597 0.436 0.893 0.964 0.835 0.243 https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

I can now add pre-1950 latest Lesser Antilles TS+ hits on record. What’s odd is that while there are none on record for Oct 10+ for the years 1899-1942, there are a whopping 7 just during the 12 year period of 1887-1898, including three during El Niño! Starting from latest: - Dec 7, 1887, TS Windwards *during weak El Nino* - Nov 27-9, 1896, TS Windwards to Leewards *during strong El Nino* - Nov 27-8, 1878, TS Leewards - Nov 1-2, 1888, TS Windwards to Leewards *during superstrong El Nino* - Oct 29, 1867, 110 knots cat 3 H Leewards - Oct 27, 1898, TS Leewards - Oct 15, 1895, TS Windwards - Oct 12, 1891, TS Windwards - Oct 11-12, 1894, H (cat 1?) Windwards to Leewards - Oct 11, 1943, TS Windwards

Going back to 1950, here are the latest TS+ hits from the east on the Lesser Antilles: - Alice of 1954 was cat 1 H in Leewards Jan 2 moving WSW: https://en.m.wikipedia.org/wiki/Hurricane_Alice_(December_1954) - Tomas of 2010 was 100 mph cat 2 H in Windwards Oct 30: https://en.m.wikipedia.org/wiki/Hurricane_Tomas - Helena of 1963 was TS in Leewards Oct 26-7: *During El Nino* https://www.meteo-tropicale.fr/en/detail-du-systeme-meteo/?Storm=AL091963 - Jose of 1999 was cat 1 H in Leewards Oct 20: https://en.m.wikipedia.org/wiki/Hurricane_Jose_(1999) - Joan of 1988 was TS in Windwards Oct 15: https://en.m.wikipedia.org/wiki/Hurricane_Joan–Miriam - Gonzalo of 2014 was cat 1 H in Leewards Oct 13: *During El Nino* https://en.m.wikipedia.org/wiki/Hurricane_Gonzalo

Regarding the above, the last couple of GFS and EPS runs for late month are suggesting there’d be virtually no chance for a BN October (2+ BN) in most of the E US. That period is still far enough away for a decent level of uncertainty to remain, but the current trend isn’t at all favorable to a cold late month with too much mild Pacific flow as opposed to cold Canadian flow. What I was hoping for and what I’m now seeing are not at all matching up. Just being real. I hope it changes. Any other opinions?

That would require a rise similar to the period of the fastest rise of this event so far, Aug 4-24. Not impossible but highly unlikely imo. We’ll see!

Indeed, what per Eric Webb’s tables is the strongest El Niño on record took place in 1877-8. It peaked at +2.9 both in NDJ and in DJF: https://www.webberweather.com/ensemble-oceanic-nino-index.html

To clarify regarding the latest versions of ONI peak for each major model, only the BoM (+2.43 in DJF) and MeteoFrance (~+2.3 in NDJ) have a super Nino now. Eric is showing Dec, alone. He has ~+2.75 for MeteoFrance. I see only ~+2.45 for Dec, which is from here: https://climate.copernicus.eu/charts/packages/c3s_seasonal/products/c3s_seasonal_plume_lfpw?area=nino34&base_time=202310010000&type=plume Here’s the summary of the latest runs: BoA: +2.43 vs +2.87 a month ago (DJF) MetFrance: ~+2.3 vs ~+2.5 a month ago (NDJ) Euro: ~+1.98 vs +2.24 a month ago (NDJ) UKMET: ~+1.90 vs +1.96 a month ago (DJF) JMA ~+1.90 vs +2.06 a month ago (NDJ) CFS ~+1.60 (DJF) vs +1.83 a month ago (NDJ) AVG ~+2.02 (NDJ/DJF) vs +2.29 a month ago (NDJ) Median ~+1.94 (NDJ/DJF) vs 2.15 a month ago (NDJ)

Regarding the idea of a partial correlation of BN temperature in Oct in the E US with BN in the following winter in the E US during El Niño, I did a rough estimate of where Oct 1-18 will be for RDU and NYC and came up with right at normal for RDU and +1 at NYC. So, for a BN full Oct (2 BN or colder), RDU would need to be ~5 BN for Oct 19-31 and NYC would need to be ~6BN for Oct 19-31 assuming those Oct 1-18 estimates verify pretty closely. That’s going to be quite a challenge. Areas further south than RDU would probably have an easier time to end up BN for the month.

Does anyone here follow GLAAM? “State Of The Atmosphere: El Niño, Positive India Dipole And Negative GLAAM” “The Earth’s atmosphere and oceans have a certain amount of natural rotation or spin, which is called angular momentum. This spin affects weather patterns. Normally, GLAAM is positive when the Trade Winds reverse blowing warm waters (arrow) from west to east. So positive GLAAM is most present during roughly 75% of all El Niño events. Currently, GLAAM is negative, which means less torque or rotation along the equator. This could potentially weaken the warm waters blowing from west to east. If it does, a cold, snowy northern Hemispheric winter would be the rule.” https://www.barchart.com/story/news/21017728/how-different-el-nino-events-affect-winter-weather-and-natural-gas-prices

Summarizing the major models I follow, this month cooled on all of them for ONI peak vs last month’s run: BoA: +2.43 vs +2.87 a month ago (DJF) MetFrance: ~+2.3 vs ~+2.5 a month ago (NDJ) Euro: ~+1.98 vs +2.24 a month ago (NDJ) UKMET: ~+1.90 vs +1.96 a month ago (DJF) JMA ~+1.90 vs +2.06 a month ago (NDJ) CFS ~+1.60 (DJF) vs +1.83 a month ago (NDJ) AVG ~+2.02 (NDJ/DJF) vs +2.29 a month ago (NDJ) Median ~+1.94 (NDJ/DJF) vs 2.15 a month ago (NDJ)

Looking at the very telling actual output for the new JMA, it cooled notably for a second month in a row and is no longer forecasting a super. Based on eyeballing, I have it (NDJ peak) no warmer than ~+1.90 vs +2.06 last month and +2.22 two months ago. It is easy to see that all months Oct-Feb cooled with January having cooled the most (see two images below). Just place a ruler along the +2 line on each and it is easy to see that it cooled. Jan is no higher than +1.7 after having been ~+1.9 last month and ~+2.05 two months ago: Sept 1st run: NDJ +2.06 Oct 1st run: NDJ ~+1.90

This means that the BoM model’s ONI peak in DJF dropped from 2.87 a couple of runs ago to 2.77 on the 9/23 run to only 2.43 in this latest run. It will almost certainly keep dropping.

The MJO is forecasted to end up weak for October of 2023 as a whole. Looking back at the 16 prior El Niños back to 1976-7, I found these 6 (38% of them) with weak MJO Octobers: 1977, 1982, 1987, 1997, 2002, and 2014 What did they have in common? - Peak ONI strength? No as two were weak, one was moderate, one was strong, and two were super strong - Average amplitude of winter MJO? Not really as only two of the six (1982-3 and 1997-8) stayed weak (mainly inside or just outside COD) all winter. 2002-3 was close as it was weak in J and F but it was strong prior to that in D. 1977-8 was the reverse of 2002-3 as it was weak in D but J and F were strong. 2014-5 was moderate through all of DJF. 1987-8 was moderate in D and J followed by strong in F. So, to summarize the subsequent winter MJO amp for these 6 weak Oct MJO cases: -D was weak 3 times, moderate twice, and strong once. -J was also weak 3 times, moderate twice, and strong once. -F was weak 3 times, moderate once, and strong twice. ——————— **Edit: Now I’ll add an analysis of moderate Oct MJOs: 8 cases 1976, 1986, 1991, 1994, 2004, 2009, 2015, 2018: again a mix of ONI peak strengths -D weak once (2004), moderate 5 times, strong twice -J also weak once (1977), moderate 5 times, strong twice -F also weak once (1977), moderate 5 times, strong twice So when comparing weak Oct MJO to moderate Oct MJO, the moderate Oct tend to keep it moderate in winter vs being weak more often than moderate during winter following a weak Oct MJO. So, there’s a tendency for some carryover. —————— Strong Oct MJOs: only 2 cases 1979, 2006 -Both had weak ONI peak -1979-80 MJO was weak through DJF -2006-7 MJO was moderate through DJF

Thanks for posting. Wow, you’ve put a lot into this! It is well thought out. 1. Do you use 1991/2020 for normals or do you use another base period? 2. Have you made a DJF NAO or AO forecast? 3. I know you said Oct would be cooler/warmer in the E/W than the Oct 1-7, 2023 temp map you posted. However, you also said that the full month would retain the look where the E is warmer than the W relatively speaking. Based on the Euro weeklies and other model output showing a BN/AN last 3 weeks of the month for much of the E/W US, I wonder about this, especially for the SE vs the W but also even for areas further N like the Mid-Atlantic states. If there are 3 weeks of AN in the W, wouldn’t a lot of the W end up AN?