bluewave

If you are adhering to the rules of sample size purism, then very few posts in this thread using El Niño winter composites have a large enough sample size. The possible subcategories this winter include questions of coupling, strength, location of warmest ENSO SST anomalies, record WPAC warmth for an El Niño, negative phase of PDO, early MJO 4-6 phases, competing marine heatwaves for forcing with ENSO, along with other factors. So there are going to be a naturally small number of past years which match this year. But that doesn’t mean we can’t try to use even a smaller sample size than we would probably want to to look for clues. Sometimes in forecasting we have to try and follow the spirit of the law so to speak when the letter of the law may be out of reach.

I picked a total of 7 El Niño years since 2000 which showed similarities in fall patterns to winter. A similarity doesn’t mean an exact carbon copy. Plus the increasing number of multiyear La Ninas may naturally create a larger sample pool of events to draw from than El Niños. We could probably reduce what officially counts as an El Nino by including coupling issues in years like 18-19 along with El Niños with -PDOs. Competing marine heatwaves may eventually result in a large enough sample size to change our expectations of ENSO events relative to climatology from earlier eras when these extreme marine heatwaves weren’t as prevalent.

A large number of individual years did work out as you posted a few posts back. My analysis covered a large portion of the CONUS. So cherry picking a few locations on the map that didn’t work out is missing the point. 20 years isn’t that small of a sample size. And if you were so concerned about the science, you wouldn’t have taken the name of a discredited stadium wave paper which proclaimed that global warming was going to level off after 2010 or pause until the late 2020s when the opposite has occurred.

There really isn’t much in the way of cold air near the coast even If a more amped pattern verifies since it’s all Pacific air getting stuck under the block.

The fast PAC Jet that keeps lowering heights along the West Coast is the main issue. Tends to suppress systems moving to our south and allow lows to our west to cut or hug the coast more. So some version of recent years issue of cutter, hugger, and southern stream suppression working against true BM tracks. Plus models have been underestimating the PAC Jet in the 6-10 day range most of the time since 18-19.

The correlation has worked out for every El Niño since 02-03. But for some reason, it didn’t really exist before that. The 3 coldest El Niño falls into the Plains and Great Lakes in 02, 09, and 14 expanded a few degrees eastward for the winter. Then the colder in Plains and warmer in the East El Niño falls of 06 and 18 repeated for the winter. I chalk this up to our new era of stuck and stagnant weather patterns. So a fall pattern can linger in some fashion into the winter.

I did find a relationship between fall (SON) temperature departures and winter CONUS departures. While this pattern just emerged in 2002, it has worked out each El Niño year since then.Very similar temperature departure patterns in the fall to winter. They fell into 3 groups. The first is the colder falls which preceded the colder winters. Next was the colder falls to the West and warmer along East Coast which repeated during the winter. The final group was the warmer falls across the the entire CONUS and the warmer winters across the Northern tier to Northeast. This fall has matched the warmer years of 2004 and 2015. But luckily, we didn’t reach the magnitude of the fall 2015 warmth. That would be a tough act to follow anyway. So somewhere in between 04-05 and 15-16 for fall departures. This would mean above average temperatures this winter near upper Midwest and Great Lakes to Northeast.

Luckily, the VP anomaly forecast into December near the dateline doesn’t look as extreme as in 2015. Same goes for the RMM response this month in 4-6 which looks less amplified. So not seeing any indication yet of that epic standing wave which developed. But even 25% to 50% of that warming would still be a warmer than normal pattern for us in December. As for later in the season, we’ll just have to wait and see how it plays out. Would like to see enough El Niño influence Jan 15th to February 28th to minimize any potential for MJO 4-6 or -PDO negative interference. I only mention that since there has never been an El Niño before with such an extensive +30C warm pool back to the Maritime Continent. In the old days El Niños had much cooler SSTs in the WPAC this time of year than we are seeing now.

We needed the strength of that one to eventually shut down the warmest MJO 4-6 phases we got in December. So while the rest of the season was warmer than average, it wasn’t nearly as warm. The blocking was able to take over later on and produce the record snowfall. So not sure if this El Niño gets strong enough to counter any warmer MJO 4-6 phases associated with that +30C warm pool near the Maritime Continent. We can hope that the warmer Maritime Continent forcing we are seeing now fades away by January and February and allows a typical backloaded El Niño response with blocking for snow even if it doesn’t get really cold. The last thing we want is MJO 4-6 phases mucking up the late winter El Niño response. So we have plenty of time to see how things evolve since we usually don’t expect much from the front end of El Niño winters.

Yeah, every single digit snowfall season in NYC was followed by a double digit one of at least 12.7”. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Snowfall Oct 1 to Apr 30 Next Season Total Snowfall 1 2023-04-30 2.3 ? 2 1973-04-30 2.8 23.5 3 2002-04-30 3.5 49.3 4 1919-04-30 3.8 47.6 5 2020-04-30 4.8 38.6 6 1901-04-30 5.1 25.4 7 1932-04-30 5.3 27.0 8 1998-04-30 5.5 12.7 9 2012-04-30 7.4 26.1 10 1989-04-30 8.1 13.4 - 1878-04-30 8.1 35.8 11 1951-04-30 9.3 19.7

Those VP charts are showing the MJO lingering in 7. The ultra long range guidance was trying to dampen the convection too much near the Dateline around the holidays. My guess is this is just the models losing the signal in the increased long range noise. As models get closer it’s easier for them to see the signal. New run Old run

Centrally or west based El Niños are colder when they are weaker than we have now like 02-03, 09-10, and 14-15. Those are the true Modokis. This event currently has some of the warmest Nino 4s on record behind 2016. In any event, we have plenty of time. Since nearly all El Niños are judged on Jan 15th to February 28th. So anything before then is a bonus and we usually don’t expect much. The hope is that we get a true Nino response later in the winter and not get interference from the MJO 4-6 regions. A cleaner El Niño response could allow us to surpass the snowfall totals of last year if we get good blocking later in the winter.

The latest EPS weeklies don’t move the forcing past MJO 7 in December as the warm pool is too strong near the Dateline. So it never achieves the classic MJO 8 look with the VP anomalies shifting well east in December. The last time Nino 4 was this warm in 15-16 it took until January for the MJO to shift over to 8-1-2. But while it was colder than when in the MJO 4-7 phases, it never got colder than average due to the overpowering jet stream off the Pacific. But we did see an eventual snowfall improvement due to blocking later in the season. The one caveat now is that the WPAC warm pool is stronger this year. So we may still get further competition from the warmer MJO phases. The RMM charts have been too fast in recent years to move the MJO out of the warmer phases. While the VPanomaly charts have been more reliable. But even they have been to fast to move the MJO to 8-1-2.

The latest EPS weeklies don’t move the forcing past MJO 7 in December as the warm pool is too strong near the Dateline. So it never achieves the classic MJO 8 look with the VP anomalies shifting well east in December. The last time Nino 4 was this warm in 15-16 it took until January for the MJO to shift over to 8-1-2. But while it was colder than when in the MJO 4-7 phases, it never got colder than average due to the overpowering jet stream off the Pacific. But we did see an eventual snowfall improvement due to blocking later in the season. The one caveat now is that the WPAC warm pool is stronger this year. So we may still get further competition from the warmer MJO phases. The RMM charts have been too fast in recent years to move the MJO out of the warmer phases. While the VP anomaly charts have been more reliable. But even they have been to fast to move the MJO to 8-1-2.

Good question. NYC hasn’t been able to drop below 36° for an average winter temperature since the super El Niño in 15-16. So I am not sure what it would take to get a winter closer to 32° like 13-14 and 14-15. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Season Mean Avg Temperature Departure 2022-2023 41.0 +4.8…2nd warmest 2021-2022 37.1 +1.0…20th warmest 2020-2021 36.1 +0.4…28th warmest 2019-2020 39.2 +4.0 ….7th warmest 2018-2019 36.3 +1.2…26th warmest 2017-2018 36.2 +1.1….27th warmest 2016-2017 39.3 +4.2…6th warmest 2015-2016 41.0 +5.9….2nd warmest 2014-2015 31.4 -3.7…22nd coldest 2013-2014 32.9 -2.2…34th coldest

Officially strong or super as per ONI probably won’t make that much of a difference on our sensible weather when we have a solid block of +30C SSTs from Maritime Continent to just east of the Dateline. December forcing in the MJO 4-7 regions is a warmer than average pattern for us. The current Nino 4s around the MJO 7 region are close to the warmest on record set during the 15-16 super El Niño.

We have been getting warmer than average to record warm winters in the Northeast since the super El Niño regardless of ENSO. So El Niño or La Niña may not be that relevant for our temperatures. Snowfall has been highly variable since the 90s with mostly all or nothing seasons. Unfortunately, last winter was one of the nothing seasons for snowfall. Mot much correlation between winter temperatures around NYC and ENSO. NYC Feb 23…+5.2 Jan 23…+9.8 Dec 22…-0.6 …………..+4.8……La Niña…2nd warmest winter Feb 22….+1.4 Jan 22….-3.2 Dec 21….+4.7 ……………..+1.0….La Niña Feb 21….-1.7 Jan 21….+1.1 Dec 20…+1.7 …………..+0.4……La Niña Feb 20…+4.8 Jan 20….+6.5 Dec 19….+0.8 …………….+4.0…..Neutral….7th warmest winter Feb 19….+0.9 Jan 19….-0.1 Dec 18…+2.6 …………….+1.1……Uncoupled El Niño Feb 18…+6.7 Jan 18….-0.9 Dec 17…..-2.5 …………….+1.1……La Niña Feb 17…..+6.3 Jan 17….+5.4 Dec 16….+0.8 …………….+4.2…..La Niña…6th warmest winter Feb 16….+2.4 Jan 16….+1.9 Dec 15….+13.3 …………….+5.9…..El Nino …2nd warmest winter

Both things can be true at the same time. The record WPAC warm pool is providing fuel for the forcing near MJO 4 to MJO 6. The near record Nino 4 SSTs are boosting the forcing near MJO 7. So we are getting a tug of war between competing El Niño and La Niña influences. This pattern translates into a warmer pattern for us in December. The hope is that the MJO 4-6 forcing can fade enough as the season progresses to allow some version of the backloaded El Niño winter climo to emerge. But as Chuck mentioned yesterday, we don’t want La Niña forcing to interfere with the typical El Niño response from later January into February.

Yeah, very Niña-like MJO activity during our last 2 El Niño Decembers.

Tuesday into Wednesday will probably be the coldest readings we see in a while.

The warmest +30C waters are spread out from MJO 4 to MJO 7 near the Dateline. So that’s why we suddenly saw the models correct warmer for early December. Some version of this has been happening most Decembers last decade.

That’s one of the issues with the smoothed out ensemble means for the day 11-15 forecasts. They miss details like the MJO and jet speed. So we end up with a trough closer to West in the newer runs and mild Pacific air across most of North America in early December. New run is warmer due to faster Pacific Jet pushing trough into West Older run cooler for our area with more ridging out West New run Western trough Old run Western ridge

My guess is that the models are picking up on the forcing slowing near the MJO 4-7 regions on VP anomaly charts. Notice how the recent runs have the forcing closer to the warmer phases. This seems to be a regular December occurrence in recent years with models initially trying to rush the warm phases. I like the VP anomaly charts better sometimes since models can really rush the RMM charts leaving the warmer phases. Notice how the new runs of the Euro are correcting stronger with the jet extension near Japan. I believe this much stronger jet tries to knock down the ridge over the Western US. Probably related to that big forcing cell near MJO 4. The silver lining for the general public outside this forum is that heating demand for most of the continent will be below average. So most will be happy to see a break on their heating bills. New run stronger jet extension near Japan Old run much weaker allowed more Western ridging

The blocking is developing but it’s favoring Europe. When we see the polar vortex shift over to Europe, it takes a lot of patience to see improvement here. Notice how there is no real cold air anywhere in North America as we head into December.

The static background state is the expanding record WPAC warm pool leading to stronger and more frequent MJO 4-6 phases and multiyear La Ninas. This can even occur during super El Niños like in December 2015. And we saw how this background state prevented the 18-19 El Niño from coupling. https://www.nature.com/articles/s41558-023-01801-6 Understanding the recent increase in multiyear La Niñas Bin Wang, Weiyi Sun, Chunhan Jin, Xiao Luo, Young-Min Yang, Tim Li, Baoqiang Xiang, Michael J. McPhaden, Mark A. Cane, Feifei Jin, Fei Liu & Jian Liu Nature Climate Change volume 13, pages 1075–1081 (2023)Cite this article 8180 Accesses 188 Altmetric Metrics details Abstract Five out of six La Niña events since 1998 have lasted two to three years. Why so many long-lasting multiyear La Niña events have emerged recently and whether they will become more common remains unknown. Here we show that ten multiyear La Niña events over the past century had an accelerated trend, with eight of these occurring after 1970. The two types of multiyear La Niña events over this time period followed either a super El Niño or a central Pacific El Niño. We find that multiyear La Niña events differ from single-year La Niñas by a prominent onset rate, which is rooted in the western Pacific warming-enhanced zonal advective feedback for the central Pacific multiyear La Niña events type and thermocline feedback for the super El Niño multiyear La Niña events type. The results from large ensemble climate simulations support the observed multiyear La Niña events–western Pacific warming link. More multiyear La Niña events will exacerbate adverse socioeconomic impacts if the western Pacific continues to warm relative to the central Pacific. https://link.springer.com/article/10.1007/s00376-020-0261-x Distinctive MJO Activity during the Boreal Winter of the 2015/16 Super El Niño in Comparison with Other Super El Niño Events Abstract Many previous studies have demonstrated that the boreal winters of super El Niño events are usually accompanied by severely suppressed Madden-Julian oscillation (MJO) activity over the western Pacific due to strong descending motion associated with a weakened Walker Circulation. However, the boreal winter of the 2015/16 super El Niño event is concurrent with enhanced MJO activity over the western Pacific despite its sea surface temperature anomaly (SSTA) magnitude over the Niño 3.4 region being comparable to the SSTA magnitudes of the two former super El Niño events (i.e., 1982/83 and 1997/98). This study suggests that the MJO enhanced over western Pacific during the 2015/16 super El Niño event is mainly related to its distinctive SSTA structure and associated background thermodynamic conditions. In comparison with the previous super El Niño events, the warming SSTA center of the 2015/16 super El Niño is located further westward, and a strong cold SSTA is not detected in the western Pacific. Accordingly, the low-level moisture and air temperature (as well as the moist static energy, MSE) tend to increase in the central-western Pacific. In contrast, the low-level moisture and MSE show negative anomalies over the western Pacific during the previous super El Niño events. As the MJO-related horizontal wind anomalies contribute to the further westward warm SST-induced positive moisture and MSE anomalies over the western tropical Pacific in the boreal winter of 2015/16, stronger moisture convergence and MSE advection are generated over the western Pacific and lead to the enhancement of MJO convection. https://www.climate.gov/news-features/blogs/enso/csi-enso-case-missing-central-pacific-rainfall