GaWx

These El Niño winters that quickly followed La Nina were significantly colder in the SE US than the prior winter: 1876-7 (cold), 1880-1 (cold), 1904-5 (very cold), 1911-2 (cold), 1925-6 (normal), 1939-40 (very cold), 1957-8 (cold), 1965-6 (cold), 1972-3 (normal), 1976-7 (very cold), 2009-10 (very cold) These weren't: - 1887-8 was slightly warmer than 1886-7 and near normal - 1918-9 was much warmer than 1917-8 and was near normal. It followed the very cold 1917-8, which was one of the coldest La Niña winters on record - 2006-7 was warmer than 2005-6 and warmer than normal - 2018-9 was warmer than 2017-8 and warmer than normal --------- Tally: - 11 of 15 were significantly colder than the prior winter - 9 of 15 were cold to very cold - 4 of 15 were near normal - 2 of 15 were warmer than normal, the most recent cases Conclusion: As one living in the SE who prefers a cold winter, I'd take my chances with El Niño this winter on a normal or colder winter based on the above history despite the two most recent cases being warmer than normal, which would keep from betting heavily on it. I certainly would prefer it over other ENSO! Keep in mind that four of these 15 were historically cold. Although this analysis is centered on the SE US, much of this can be used for other areas as well. That includes seeing which were the 15 El Niño winters since the late 1800s that quickly followed La Niña and analyzing those 15 winters for one's own region.

More on El Niños in the SE that quickly follow La Niñas: These El Niño winters that quickly followed La Nina were significantly colder in the SE US than the prior winter: 1876-7 (cold), 1880-1 (cold), 1904-5 (very cold), 1911-2 (cold), 1925-6 (normal), 1939-40 (very cold), 1957-8 (cold), 1965-6 (cold), 1972-3 (normal), 1976-7 (very cold), 2009-10 (very cold) These weren't: - 1887-8 was slightly warmer than 1886-7 and near normal - 1918-9 was much warmer than 1917-8 and was near normal. It followed the very cold 1917-8, which was one of the coldest La Niña winters on record - 2006-7 was warmer than 2005-6 and warmer than normal - 2018-9 was warmer than 2017-8 and warmer than normal --------- Tally: - 11 of 15 were significantly colder than the prior winter - 9 of 15 were cold to very cold - 4 of 15 were near normal - 2 of 15 were warmer than normal, the most recent cases Conclusion: As one who prefers a cold winter, I'd take my chances with El Niño this winter on a normal or colder winter based on the above history despite the two most recent cases being warmer than normal, which would keep from betting heavily on it. I certainly would prefer it over other ENSO! Keep in mind that four of these 15 were historically cold.

I'm also expecting El Nino and I'd welcome it with open arms as they in the SE overall average a fair bit colder than La Niña and even somewhat colder than neutral due to the tendency for a higher PNA working in concert with a typically more active subtropical jet. This means that the stubborn SE ridge is usually weaker during El Niño. El Niño right after La Niña can really shake up the pattern and help lead to a much colder winter. Examples: 1904-5, 1911-2, 1939-40, 1957-8, 1965-6, 1972-3, 1976-7, and 2009-10. But we'll have to see about the SER as the near record warm western equatorial Pacific and strong AMO have been supporting it. The major El Niño forecasting failure year (including for me) of 2017 gives me pause and thus prevents me from getting overconfident about it returning. This was a post I made yesterday in the main ENSO thread: "Currently, 14 of 16 dynamic models (88%) are predicting an oncoming El Niño. How does this stack up to prior March predictions? I can see them going back to 2005 at the link below. That gives us a decent sample size of 19 years. - This March's 88% is 3rd highest of all 19 and 2nd highest of the 14 not already El Niño. That's strong support for an upcoming El Niño. - 2015 was at 94%, but that was already El Niño unlike now. Regardless, the models did very well in not only calling for El Niño to continue but for it to strengthen. - The other one at 94% was the already noted 2017, which turned out to be by far the worst failure of the 19 being that it ended up La Niña. - What % of models were predicting El Niño before other El Niños that materialized? - 2018: only 46% though it was still La Niña then making it challenging for the models. - 2014: 69%, a good job since ENSO was still cold neutral at the time - 2009: 60%, a good job since ENSO was still La Niña at the time - 2006: 67%, a good job since ENSO was still La Niña at the time So, this also reiterates that 2023 being up at 88% is strong support for El Niño. The main inconsistency is 2017. ----------------- Monthly ENSO model predictions back to 2005: https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/ "

March in the SE from @pcbjr in Gainesville to @Coach McGuirkin SE VA and about all places in between will end up slightly warmer than Feb and slightly warmer than normal. Despite the impressively cold mid-month (coldest since January in many places and even late December in a few places) induced mainly by the mid Feb major SSW along with an even weaker SPV the last days of Feb, this wasn't able to overcome the very warm first week in combination with mild dominating much of the late month. It took 3 weeks from the major SSW for it to finally get cold in the SE. Although warmth during and just after an SSW is favored/common (as shown by the image I posted), cold from a fully downward propagating weakened SPV (manifested by a solid -AO/-NAO) more typically takes only ~10-14 days to arrive in the SE as opposed to 21 days. The impressive AO/NAO drop started within 10-14 days, but the cold lagged behind. The strong -PNA/unfavorable Pacific/SE ridge likely was the main reason for the delay. So, although the cold that we did get was quite impressive, it wasn't as long in duration as it could have been without the very stubborn Pacific that first had to be overcome. Furthermore, an even stronger -PNA quickly returned for late month.

Interesting stuff! Thanks for posting that. - Regarding the Oct-Mar rainfall for 2018-9 at SF, it was at 23.33" vs the 18.96" longterm mean. So, not anywhere near top 10 wettest, but still pretty wet. - Although 8 years makes it by far the record longest between El Niño years as you stated over the last 70 years vs current record of 5 years, the record longest going back to 1850 using Eric Webb's data is 10 years (1941-2 to 1951-2).

Do you or does anyone else know where to find PNA or PDO data for individual months covering 1850-1899?

Currently, 14 of 16 dynamic models (88%) are predicting an oncoming El Niño. How does this stack up to prior March predictions? I can see them going back to 2005 at the link below. That gives us a decent sample size of 19 years. - This March's 88% is 3rd highest of all 19 and 2nd highest of the 14 not already El Niño. That's strong support for an upcoming El Niño. - 2015 was at 94%, but that was already El Niño unlike now. Regardless, the models did very well in not only calling for El Niño to continue but for it to strengthen. - The other one at 94% was the already noted 2017, which turned out to be by far the worst failure of the 19 being that it ended up La Niña. - What % of models were predicting El Niño before other El Niños that materialized? - 2018: only 46% though it was still La Niña then making it challenging for the models. - 2014: 69%, a good job since ENSO was still cold neutral at the time - 2009: 60%, a good job since ENSO was still La Niña at the time - 2006: 67%, a good job since ENSO was still La Niña at the time So, this also reiterates that 2023 being up at 88% is strong support for El Niño. The main inconsistency is 2017. ----------------- Monthly ENSO model predictions back to 2005: https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/

@bluewave posted this table: Time Series Summary for SAN FRANCISCO DOWNTOWN, CA Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Precipitation Oct 1 to Mar 30 Missing Count 1 1862-03-30 47.73 0 2 1890-03-30 43.33 3 3 1998-03-30 39.76 0 4 1868-03-30 36.23 0 5 1878-03-30 33.93 0 6 1973-03-30 33.67 0 7 1983-03-30 33.50 0 8 1850-03-30 32.64 0 9 2023-03-30 32.30 1 10 1867-03-30 32.15 0 --------------------------------- I have some additional observations regarding this table of highest SF 10/1-3/31 precip amounts based on Eric Webb's ENSO tables that go back to 1850: - In addition to the super-strong El Niños of 1997-8, 1982-3, and 1972-3 being listed, there's also 1877-8 in there at #5. That's intuitive since it also was a super-strong El Niño, even stronger than the four since 1972-3 being that it peaked at +2.9. So, 4 of the wettest 7 were super-strong El Niños. - But 2023-4 wasn't the only La Niña in this top 10 wettest list. The 2nd wettest, 1889-90, was La Niña. Not just that it was La Niña, it dipped to -1.4 making it at the time the strongest La Niña since at least 1849-50 and significantly stronger than the current one. - Also, the 8th wettest (1849-50) was a La Niña that dipped to -1.2. - So, in addition to the intuitive four super-strong El Niños being in there, almost as many somewhat counterintuitive non-weak La Niñas (3) also made the top 10. --------------------- Eric Webb's ENSO tables (these go back to 1850): https://www.webberweather.com/ensemble-oceanic-nino-index.html

I'm currently favoring El Niño later this year though not yet betting the ranch. In addition to the strong model support of 14 out of 16 models, I see moderate support based on there not having been more than five years between any two of them since 1950 per this: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php So with the last one being 2018-9, 2023-4 would be right at five years making El Niño kind of due this fall/winter. But I say moderate support rather than strong support because Eric Webb's ENSO tables, which go way back to 1850, show a good number of longer than five year intervals between El Niños, including five cases of 8-10 year intervals: 1941-2 to 1951-2: 10 years 1930-1 to 1939-40: 9 years 1905-6 to 1911-2: 6 years 1888-9 to 1896-7: 8 years 1868-9 to 1876-7: 8 years 1855-56 to 1864-5: 9 years 1848-9 or earlier to 1855-6: 7+ years So, after looking at this earlier period, one might think we're actually way overdue for the next 6+ year interval between El Niños. https://www.webberweather.com/ensemble-oceanic-nino-index.html

What a refreshing day with upper 60s highs, upper 30s dewpoints, and plentiful sunshine. Winds were light. Looking forward to a walk soon in the cool 50s with dewpoints still down in the 40s.

As @ORH_wxman stated, the 2015-6 El Niño was well predicted. Even as early as March of 2015, the dynamic models had a mean peak of +1.2 already by summer: https://iri.columbia.edu/our-expertise/climate/forecasts/enso/2015-March-quick-look/ However, the 3/2015 models were initialized with the already existing weak El Niño. So, unlike now, the models had help from it already being El Niño. They're probably more apt to predict a moderate+ El Niño later in the year when it is already weak El Niño vs if it is only neutral at initialization like the current case. But despite the current neutral initialization the dynamic model mean is up at +1.0 by summer, which though not as strong as the +1.2 summer mean of the March of 2015 dynamic models is still quite notable: https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/ Then again, a whopping 15 of 16 dynamic models in March of 2017 were progging El Niño by summer with a similar neutral initialization: https://iri.columbia.edu/our-expertise/climate/forecasts/enso/2017-March-quick-look/?enso_tab=enso-sst_table So, don't bet the ranch this early.

I feel there's a good chance for El Nino later this year. However, based mainly on the models I felt the same way throughout the spring of 2017 for later that year (as did the CPC, JB and many others). It took me til July to give up on an oncoming El Nino that year. It turned out there was La Niña that fall/winter! So, I know never to bet anything close to the ranch on the upcoming fall/winter ENSO state this early due to unpredictability. I may bet on it, but not too heavily. Here is the AmericanWx 2017 ENSO thread, which illustrates well the epic failure of the spring 2017 model forecasts that suggested a very good chance for El Niño by summer: From that thread, this post from 9/13/2017 summed it up very well: "How can it be that we went from a good chance at an El Nino, to now a very good chance at a La Nina? Is it that unpredictable?"

I've read several articles written by Dr. Lee about certain setups in the troposphere often leading to SSWs via "heat flux". This one cited that high Scandinavian SLP coexisting with a very strong surface cyclone centered just off of NE Greenland is a pretty good indicator of an SSW soon after: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD030940 One of these strong SLP dipoles occurred during early Feb of 2018, just before the 2/12/2018 SSW. It just so happened that it also existed in early Feb of 2023, just before the major SSW of 2/16/2023.

This source has extensive SSW data since 1980 in table 3 with rankings of minor, major, and extreme. Note that Feb of 2018 is ranked as "extreme", one of only eight out of the 43 in the table: https://acp.copernicus.org/articles/23/1259/2023/acp-23-1259-2023.pdf There are no November SSWs in that table. One of the most memorable in terms of influence on the E US is the extreme SSW of 1/1/1985, which lead to extreme cold due to record blocking 2.5-3 weeks later. But even extreme SSWs don't always propagate downward enough to later lead to cold.

From @bluewave post: "The pattern produced record 80° warmth at Newark in February 2018 before record March blocking produced 30” snows on Long Island." In addition to the influence from CC, both the Feb of 2018 E US warmth/record high H5 heights and subsequent Arctic blocking/cold/snow in March of 2018 were made possible by one of the most extreme "major" SSWs on record. This major SSW was centered on 2/12/2018: https://acp.copernicus.org/articles/19/10303/2019/acp-19-10303-2019.html Though not always, it has been common for there to be strong warmth in the E US during the first 15 days after recent major SSWs followed by a sharp change to colder during days 16-30 for those SSWs that propagate downward into the troposphere and then lead to the development of a -AO.