Stormchaserchuck1

I don't think 13-14 is a bad analog, but the probability that it was going extreme did start to come up in the Fall, when the N. Pacific ridge went Polar. We would need to follow that closely imo to see a similar Winter pattern. 5/6 Winter's lately have been +WPO.. chances are it is more neutral this Winter, and the 21-22 Winter where it was neutral is a decent analog, although the timing of things may be more mixed (We had such an extreme "new" Dec -PNA that Winter that it flipped to +PNA for January).

Am I reading that right, -2.88 PDO in August? And the last 4 months have all been below -2.88? Wow! The PDO has a really strong correlation with the N. Hemisphere H5 pattern Oct-Dec. If we see -EPO/-WPO it probably won't be until the Winter imo.

Weak is just a less amplified state of the same thing.. Moderate/Strong ONI's translate to a 100dm Pac ridge in the Winter, while Weak's have translated to a 50dm Pac ridge. Our historical composite is too limited to assume Weak Nina's are automatically cold.. I remember a lot of talk about this in the early 2000s when the historical composite was very cold.. but then yeah, 5/5 of the last Weak Nina's have been warm. "Weak" just means that other factors like the NAO/AO may have larger credence.

I think the cold on the West Coast is partially because we had such a cold trough on the East coast the last few weeks.. We do still need some level of mid latitude cooling in the mix, not just all +pna/-pna. The heat wave in the SW, US with record streaks of 100+ for Phoenix and Las Vegas will still translate to super warm somewhere as the Fall jet stream gets going. History shows that those conditions there in the Summer do lead to some +PNA conditions in the Wintertime, usually in December, but a lot of times raw temperatures in the SW, US do lead the Midwest and East Coast somewhere down the road.. I'd rather them be cold than warm.

Huge Omega block being modeled This fits the pattern that we've seen for the last 5 years

No problem. We've lost arctic ice on the Pacific side and since then they have had Wintertime High pressure in the PNA region, while ice has stayed on the Atlantic side, near Greenland, and we have seen more low pressures in this region in the Wintertime. @bluewave Can probably point you in a good direction with literature on the subject.

January NAO.. Will it be a -PNA October? Pretty good correlation here The rest of the year NAO correlates at 51-54% with the Winter NAO, but October is the only month of the year where the correlation is <50%. This is especially true in JFM, where it holds a 55% opposite correlation

I said the -NAO/-pna/+epo correlation started in 2013, but when I looked back at cold seasons following the super arctic ice melt in 2007-2012, it appears that correlation was true even back that far. More cold did make it to the surface in the eastern 2/3 of the CONUS though, as bluewave pointed out. That pattern has moderated a lot lately, although last January we saw a pretty good pattern break, having some -NAO-driven cold.

We are +0.50 right now for DJFM (with 0.54 sd, 50% chance DJFM NAO comes in -0.04 to +1.04). A little less positive than I expected. In May we had a negative reading, so the warm pool later in the year has only been a part of the total measurement.

In 08-09, we started to see N. Pacific High pressure hit record levels. That was the first time that really did it in satellite era. That feature has become very strong at times in recent years, even popping over +600dm in Dec 2021. Since the arctic sea ice is melting on the Pacific side, and holding near Greenland on the Atlantic side, I do think that makes some sense.. especially since when the extreme ice melt happened in 07-12, we started seeing that N. Pacific High pressure become more frequent. It's probably not perfectly linear, but I do think since that whole western side of the Arctic circle melts in the Summer, it would flex High pressure over the north Pacific Ocean.

That's a good point. I think the correlation is sea-level height, sometimes reflected by surface SSTs. May-Sept water temps in that region has a strong correlation to the Winter NAO.. right now a custom index I made is coming at about 0.70 (+0.54 SD chance we see DJFM NAO come in around +0.70). Also, October is the only month of the year where the NAO has an opposite correlation to the Winter.. I know we have a big -NAO showing up on models for the end of Sept, but I've never really checked to see if that October opposite correlation runs into late Sept. Right now, I would say it's likely that we have a +NAO Winter.

Yeah, seriously. It seems like when the arctic ice melt stops, these massive ridges blow up. This has been the trend for many years now..

Las Vegas and Phoenix having such a consistently hot Summer does correlate to +PNA conditions in December, and sometimes it carries past then.. will be interesting with a La Nina and strong -PDO, which suggest the opposite.

I do believe that weather derivatives trading does effect the weather.. I'm probably in the minority though. Does anyone know why, probably related to arctic sea ice, a -NAO would correlate with -pna/+epo and +NAO correlates somewhat with +pna/-epo, once the cold season comes about? Another thing is sea level height.. I've connected this with subsurface water temps, especially near the thermocline. We've had a classic +NAO pattern according to sea-level height since 2011, while H5 has sometimes featured anomalous ridging near Greenland.

I contest that it is something other than +AMO and CC for why the NAO has held this correlation since 2013. It might even have to do with Summer arctic ice melt, as Greenland has held its core, and the Pacific side has gone completely iceless.. The lowest Summer arctic ice melt was 2012, then the -NAO starts connecting with dual-ridging (either over N. America or -PNA) in 2013, and carries it from that point forward, even intensifying after 2017. We see an ice melt season that is almost #2 this year, then there is this big -NAO/-PNA pattern once the cold season starts progressing on the Northern Hemisphere. It's almost like a "stop" is in place, and there is dual-ridging around Greenland at other times of the year (if someone has a more scientific reason, come forth).

Best SOI match I can find where it didn't do much all year then started going positive in the Fall is 2007.. If someone has done more in depth research in that regard, correct me if I'm wrong. 1999 waned in the Spring/Summer then strengthened again in the Fall. That's about all I could find going back to 1950. It usually starts going into a phase earlier.

We are also seeing this strong -PNA pattern for the next 15 days as the ENSO subsurface is cooling again.. 30-day SOI finally made it above 10. It seems to be re-organizing further west. This is actually quite a west-based cold pool for this time of year. Imo, that could slim the chances for warm ENSO next year. It also makes it more probable that the La Nina tries to become more west-based at the surface in the coming months. I'm thinking a more west-based subsurface cold pool/La Nina may actually weaken the chances for a -EPO Winter.. we'll have to see how it evolves in the coming time. Those +SSTAs near Japan are very +WPO. All I have going for that counter-argument is that the state of the WPO/EPO usually flips after a long, sustained phase, which have seen on both monthly and yearly scales, and this is the time period where it usually happens.

@40/70 Benchmark See how the -NAO is correlating with -PNA/+EPO. The RNA flexed here, compared to before, when the pattern becomes predominant. It's not perfect, but there is a correlation in place. https://www.meteo.psu.edu/ewall/ENSHGTAVGNH_0z/ensloopmref.html

Interesting that 13-14 was cold ENSO right in that spot where I think it has it has a cold correlation I've posted this before but anti-Strong El Nino's: Furthermore, there is not much of a PDO correlation when the highest SSTA's are over that equilateral Pacific coldest water region I contest that true El Nino's (warmest anomaly over equilatoral Pac coldest SST region) are warmer than people think, and true La Nina's are colder than people think. Furthermore, if you go all the way east-based with Nino 1+2 as the dominant region, the mid-latitude cell effect directly north of it is actually over North America, not the Pacific Ocean. Something to keep in mind going forward.. if the La Nina remains strongest in Nino 3. I think a lot of the seasonal models are looking for feedback from the -PDO, trying to make it more west-based..

I'll have to do an updated analysis this week.. I think it's coming in around 0.65-0.70 for DJFM Nice write up on here by the way. It was a good read.

October has been a wet month in the Northeast for the last 20 years

Nice +NAO signal in January with a Sept -PNA

Another thing with the -PNA roll forward, is it might support warming ENSO conditions in the late Winter/Spring:

I would definitely bet on a warm October for the CONUS. The PDO also has a strong correlation in October:

Really strong -PNA on todays 12z GEFS. +300dm, 594dm ridge in a few days. This is, not coincidentally, as ENSO subsurface is cooling again. We will have a near record breaking Aleutian ridge for March-Sept 2024, as ENSO subsurface has been near "Moderate Nina" range the whole time. Next 7 months (correlation is opposite):