bluewave

Yeah, I only posted the guidance for the next 15 days along with actual pattern for the month so far. The AIFS-ENS has been doing very well with both the 500mb and storm tracks including hurricanes. The EPS weeklies beyond 15 days and other guidance is lower skill. But they have developed an AI bias corrected version (PBC) of the EPS weeklies that they claim has better scores than the weeklies do. I will post some forecast images from this new AI bias corrected EPS weeks 2-6 when and if they become available to the general public. https://www.nature.com/articles/s41586-026-11126-x?utm_source=x&utm_medium=social&utm_campaign=nature&linkId=64119704 Decision-makers rely on weather forecasts to plant crops, manage wildfires, allocate water and energy and prepare for weather extremes1,2,3. Today, such forecasts enjoy unprecedented accuracy as far as 2 weeks thanks to steady advances in physics-based dynamical models and data-driven artificial intelligence models4,5,6,7,8,9,10. However, model skill drops precipitously at subseasonal timescales (2–6 weeks ahead) due to compounding errors, systemic model biases and the chaotic nature of the atmosphere11,12,13,14,15. To counter this degradation, we introduce probabilistic bias correction, a machine learning framework that substantially reduces systematic error by learning to correct historical probabilistic forecasts. When applied to the leading dynamical and artificial intelligence models from the European Centre for Medium-Range Weather Forecasts (ECMWF), probabilistic bias correction doubles the modest subseasonal skill of the AI Forecasting System16 and improves the skill of the operationally debiased dynamical model17 for 91% of pressure, 92% of temperature and 98% of precipitation targets.

Looks like a fairly average temperature pattern over the next 5-10 days. As the historic El Niño continues to intensify, the ridge axis is forecast to shift closer to our area. So the core of the warmth which has been to our west in early fall is forecast to shift east from late October into early November.

Same general theme with more amplitude and warmth potential.

The models are developing two upper low pressure centers in the North Pacific as we head into late October. One area of lower pressures has already been developing over the Bering Sea through the first 16 days of October. The next center is forming over California and the Baja. My guess is that the stronger mid-latitude pattern which has been keeping the big ridge east of Japan is currently overlapping with the super El Niño forcing. Almost like a filter if you like. So this leads to the persistent -PDO that we have been experiencing instead of a +2.00 PDO which we would normally be getting with such a strong El Niño and +PMM. With such an historic east based event, the trough getting pushed into the West Coast will cause the Nino ridge to persist from the Upper Plains across the Great Lakes and into the East. October 500 mb pattern through the 16th Forecast into late November

The forcing has had more of an eastward lean than 1997 did so far. Notice especially how much stronger the forcing was during the Southern Hemisphere winter closer to the West Coast of South America. Also the extension of the forcing into the Southwest CONUS has been stronger early on than 1997. This make sense it’s the most east based event on record so far.

January 1998 had dual forcing with one cell in Nino 3.4 and another near 1+2. The dominant forcing wound up shifting more eastward back to 1+2 in February. Both months were equally as warm. So we are just going to have to wait and see how the finer details within this much stronger historic event work out.

This developing historic El Niño has had a much stronger ridge sitting to our west in the means since last spring than we have seen before for the early development time period. Toward the end of the month the ridge begins shift eastward closer to the Northeast. The further east ridge axis is typically what we see from super El Niño events in the past heading into later fall and the winter.

The next week to perhaps 10 days looks like a northeast flow special with low pressure sitting just offshore and high pressure to the north.

The actual winter temperatures were significantly colder during the 1990s than since the warmer baseline shift in 2015-2016. Options Selected for plot Variable: Temperature Type: Average Anomaly Season: Dec to Feb Number year(s) in composite: 21 Years in composite: 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 -2015 -2016 -2017 -2018 -2019 -2020 -2021 -2022 -2023 -2024 -2025 Climatology base period: 1961-1990 Contour Interval: default

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.