bluewave

December 1997 started out record warm across the Northern Tier. But it took until January and February for the record warmth to build east. Every super El Niño has a slightly different fingerprint. So the months which have the absolute warmest overall departures can vary a bit among events. Even that winter back in the much cooler 1990s was able to string together three +10 months at various locations. December to March 2015-2016 had two +10 months. December to February 2023-2024 also had two. None of the seasonal models prior to those winters indicated such extreme warmth would occur. As they tend to greatly underestimate the actual warmth with super El Niño events.

This has been one of the warmest first half's of fall for the entire CONUS. Weather and climate statistics are just pure numbers which didn’t contain any agendas. Most of the area finished up warmer than average in September against the warmest 1991-2020 climate normals. So even relatively low departures can still be ranked fairly high. The smaller warm departures here still rank as the 13th to 15th warmest September 1st to October 15th. This is due to September and October being two of the fastest warming months near 1° per decade since the 1980s. I get it that since this warming has become so thoroughly normalized, most people including yourself probably don’t recognize a warm pattern anymore unless it’s a top 5 or a top 10.

Yes, still warmer than the Euro for the DJF period averaged out. Each of the winter months in 1997-1998 were very warm. The warmth in December 1997 was focused in the Upper Plains and progressed eastward in January and February. We haven’t had MC forcing going back to the spring and have had no shortage of record warmth across the CONUS. Also remember 1997-1998 super El Niño had no MC forcing and was one of the warmest winters up until that time. So the moral of the story is that nearly anywhere that +30 C warm pool forcing sets up in the tropics is going to produce intervals of record warmth. What you don’t realize is that stations in the CONUS have had 17 DJF months across most winters since the temperature baseline jump in December 2015 exceeding +10 in spots. I am also sure you probably aren’t aware that none of the seasonal models successfully forecast any of these 17 DJF records for the given locations before the month in question began from 1 month or more ahead of when the months began. The Euro forecasts issued on the 5th of each of those months were sometimes even too cool for where the warmest conditions were located. Especially when the warmth was focused from the mid to later portions of those months. It generally did better when the warmth began early in the month and persisted. Heck, you would be hard-pressed to find many model forecasts that showed those areas even +5 or warmer. These record +10 months have occurred under a wide variety of ENSO conditions. While seasonal forecasts can sometimes successfully show the locations of the warmth, they always miss the magnitude of the warmth. Remember our last much weaker super El Niño in 2023-2024 produced a +10 winter averaged out over 3 months in the Upper Midwest. The Euro forecast that region to be near average so it was 10° too cool. So it’s not being controversial or edgy to state that there will probably be multiple +10 months from December to March this winter that none of the seasonal models are indicating right now. The models like the Euro forecast in °C so we have to convert. The warmest it has for this winter near the Northern Tier is +2C or greater. This translates to +3.6° F or warmer. I will take the over on that where it’s currently placing the warmest potential.

The Euro is probably the warmest of the seasonal guidance. Remember that model was much too cool going into the 2023-2024 winter. This winter forecast is even warmer than that one was. So my guess is significantly warmer than the current Euro is showing.

The entire CONUS should be warmer than all the guidance with the warmest anomalies along the Northern Tier states right to the East Coast.

I think an even bigger story than the warmth this winter will be the shift to a much warmer base state from the late 2020s into the 2030s.

My early winter guess is that the temperatures will be significantly warmer than any of the current seasonal models are forecasting. The temperatures for the first half of fall have been warmer than any other super El Niño year on record. Plus this is the strongest El Niño by a significant margin.

Will be interesting to see if we can make it two consecutive years with elements of the winter pattern emerging in November.

Some of the models clear NJ out enough this afternoon for another run at 80°. Would serve to enhance the instability ahead of the severe storm potential later today. Frost vs first freeze for Sunday morning at the usual cool spots will be contingent on whether the winds can go calm for radiational cooling under the big high.

Yeah, starting to see the SW CONUS trough develop in response to the forcing extending into that area from the EPAC.

Multi-year La Ninas prior to 2018-2019 didn’t produce persistent record ridging east of Japan leading to the record upper ocean heat through the 2020s. So are correct this pattern is not being caused by the canonical -PDO of the past which was defined more by cooler SSTs in the EPAC rather than historic warmth east of Japan. It’s a whole new type of pattern outside the typical PDO. This new type of mid-latitude ridging pattern was able to persist through the spring into the present. It’s described in the papers as Pan-Basin warming overshadowing the robust Pacific Decadal oscillation. So it’s the overlapping influence of this new pattern combined with the the super El Niño forcing leading to the ridges being much stronger further to the south than has been in the case during past developing super El Niño springs into the fall. Pan-basin warming now overshadows robust Pacific Decadal Oscillation https://www.nature.com/articles/s41558-025-02482-z Remarkable Changes in the Dominant Modes of North Pacific Sea Surface Temperature https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078

I also agree with Snowman that the forcing could be stronger further east than the models are showing since this is such an extreme event.

With the historic +30C warm pool pushed so far to the east, we are just going to have to wait and see what effects the western extent of the +30C warm pool are relative to the eastern side. Plus the pattern since May has been the seasonal models underestimating the southward extent of the ridging across the CONUS. So it’s possible the typical super El Niño ridge position south of Hudson Bay gets shifted further south than usual. The ridge wound up further south than the 2023-2024 seasonal winter forecasts and that was a much weaker event than this one. This stronger mid-latitude ridge has been leading to the persistent -PDO +AMO pattern during the 2020s.

I don’t think we were discussing the same exact parameters. The Nino 3 Euro forecast is nearly identical to the JMA keeping the Nino 3 anomalies over +4 into late January or February. The Nino 1+2 forecasts for both the JMA and Euro are similar. The reason I posted the JMA is that the Euro doesn’t have an absolute forecast on their site only the anomalies. So we have to work out the Euro absolutes manually. So even if the actual Nino 1+2 absolutes top out at say 29.5 C, there will likely be +30C actual SSTs just to the north near Central America or even near southern Mexico. You can see the forcing bridge on the Euro developing linking Nino 3.4 all the way over to Central America. This is signaling how far east the +30C warm pool is going to be similar to the JMA and Euro absolutes.

I have been taking about the importance of the +30 C warm pool for years now. Back over the summer we were discussing the potential of the +30 C warm pool off of Mexico linking up with the Nino +3 +30C warm pool. So not sure what resistance you are referring to.