Stormchaserchuck1

18-25 last season was a bold prediction.. It ended up verifying on the bottom end.

Well the PNA isn't changing. Today's daily reading is approaching the most negative daily since December 2021. it's looking more like those +PNA this past Winter were more a blip than a change in the long term state.. remember, 2020-2024 was the most negative PDO on record going back to the 1800s, and October 2024 had the lowest monthly PDO on record. It may take some time to change that, although I do think a more active sun could help. What we are getting now is a -NAO, which just hasn't been happening in the Winter, although that could of course change going forward.

We have been getting -EPO's, and even -PNA's can deliver big cold shots. There have been a few cases of good -AO's too with 500mb ridging over the Davis Strait and Greenland. Lack of clear +PNA and -NAO is why the SE ridge has persisted and storm tracks have not been benchmark. There have been I think 3 Winter months of +PNA/-NAO since 2016 (when it should happen 1/4 times). We did get +PNA/-NAO for the first 2 weeks of January in 2025, and it did give DC an 8" snowstorm. The reason it didn't hit further north was a lot because of a "Moderate Nina-like" STJ. Because of these indexes the cold has not spread east, and has been confined to the Midwest. They have had some impressive cold shots in the Midwest though. When the global temp is +2F higher, the cold is not going to be as widespread, but the indexes have been a large part of the problem, especially wrt snowfall. +PNA/-NAO is 5x more likely to give a benchmark storm track than -PNA/+NAO.

We're not getting that tripole Atlantic SLP pattern that you see in April-May's before hyperactive seasons -- it's actually more opposite, +NAO.

AAO correlation worked out last year - It was a very negative Aug/Sept AAO, and that rolled forward to a pretty strong signal on a cold December/January, -AO, North Pole was +0.5 correlation rolled forward. AAO has been very positive March - May, all but like 5 days positive. How that rolls forward to the following N. Hemisphere Winter +9 months is a lot of time, but it's an ok signal. This is what I would think +AAO would look like down the line (slight correlation with AO/EPO)

Importance of the +PNA for coastal low tracks bluewave Low's hug the coast in that pattern. CPC says it was +PNA, but the 500mb maps don't show that. We didn't have that piece in February. We had that piece in Feb 2016, and somewhat Feb 2014 (but it was much more -WPO in Feb 2014). WPO air temp correlation in Feb (opposite) - +200dm anomaly overpowered and kept Feb 2014 cold. +NAO was also further east - -200dm over England in Feb 2014. This one was closer to us.

^I would say there was more +PNA, low pressure over the north Pacific in those two analogs. Feb 2014 looks like a pretty good N. Hemisphere 500mb match though. It takes about 6 days for a Pacific-PNA change to work its way to the SE ridge. We had a strong Aleutian High late Jan-early Feb. The south-based +NAO kept the SE ridge amped after that, without a major North Pacific trough present to cut it down. AO 50 degrees further north is not a big deal when there are strong anomalies closer, and the Pacific had a large part to do with the colder patterns in those 2 analogs.

Nice link! That -AO was completely over 90N, and the NAO was raging positive to the south of Greenland, putting a ridge over Europe and a SE ridge. I don't see that pattern as all that anomalous. When the AO first went negative, we had to have to some time to change the heavy Aleutian ridge that happened in Late January/early Feb. Remember how the Polar/mid-latitude Cell's work - a ridge centered over 90N puts a trough at 45N. And in the Atlantic at 45-50N was a massive low, since this one was closer it impacts us more. -5 AO's of the past had an arctic high pressure further south.

I think the more realistic scenario is by the time the decadal NAO shifts to negative (could be 20 years), the global temperature would have caught up with the impacts of the index, neutralizing it a little bit. However, this 7-10 year snow drought is so extreme, that we will probably see a bump when more -NAO conditions prevail.

Not really a big deal imo in the context of this conversation. The PNA has been negative, and the NAO has been positive. There's a +1-2 global warming happening but that's the everything

I think we'll start warming up around the turn of the month.

Because of a retrograding -NAO. But again, the NAO is not sustaining for more than a few days, and is rapidly going back and forth between positive and negative phases. bluewave was right in that observation. Longer term it should warm up around the beginning of June.

If the daily PNA gets near -2, that would be the first time since December 2021. CPC +PNA that we saw this Winter has not sustained.

Nice Aleutian ridge on models (-PNA) May 21 - June 1. Here's the correlation with US Temps (opposite)

I definitely expect the PDO to start changing, maybe because of this more active solar period. One "bone" with this is, +3-6 years after a Strong Nino and +2-5 years after 4/5 La Nina's, we see El Nino's happen over La Nina's about 2:1.. I think we have a higher likelihood for El Nino in 26-27 and/or 27-28.. that may help to change the PDO, ideally. I do think this La Nina cycle that we have been in since 98-99 won't last much longer. We had near record winds in the Northern Hemisphere this Spring.. that is +pdo How impressive is the global temperature though with 14 La Nina's and 8 El Nino's in the last 27 years.. if ENSO was more even, it would probably be an even higher global temperature over that time (and it's already kind of gone exponential).

Yeah, I'm just saying the cycle is long so it could take decades to fully change.. Since Winter 11-12, 83% of the Winter months have had +NAO [CPC]... Given that we are still near the peak and active Solar Max, I would say the odds right now are 70-75% that next Winter is +NAO (DJFM). I agree that it should start coming down after that, but it may take up to 20 years to leave the decadal +NAO state. The 1920s were very positive, and although the 1930s did see a substantial drop, the 1940s and early 1950s went back to positive.. if you smooth that all out, it's about 20 years after a peak phase for it to come down to neutral. I would say the Solar Min in the late 2030s is the big one. Also just being outside in the Winter.. I can feel the Atlantic subtropical jet, see it in the cloud cover and stuff. That's why I've kind of intuitively known that snowfall isn't big for the last 10 or so years. And I still feel that as strong, being near a peak, no change anytime soon.

Here's what I'm looking at Ray

The decadal NAO may be more realistically 20 years from changing its state. Early 1900s - positive, 60s and 70s - negative, peak positive lately?

The Aleutian ridge due to CC is a weird one for me. There has been a lot of research done linking El Nino's with global warming, because there is a SD difference in strong El Nino events and the global temperature, up to a year later. That's more +PDO/+PNA, but everything skews warm so maybe not so much of an anomaly.. but I think it's a decadal pattern we are in, possibly due to the low sunspots in the 2000s/2010s.

-NAO block >5760dm subtropical ridge completely covering Iceland hrs 60-120. It retrogrades after to become a solid -PNA in the North Pacific, continuing the -NAO/-PNA correlation that has been so present since 2013.

Especially in February and March. Lack of a 50/50 low was also a problem for that storm, and there was a ridge off the west coast, not a trough, keeping the flow more zonal. We usually see a big +PNA Gulf of Alaska low and 50/50 low for big snowstorms... those two negative anomalies are even higher in the mean than arctic and NAO blocking, at least in the Mid Atlantic.

There was a -300dm 500mb low at 45-50 N in the North Atlantic. The AO was all the way over the North Pole. The closer anomaly usually wins.. in this case a strong low pressure at 45-50N correlates with slightly above average temps across the Northeast coast. I was on this board 7+ days out saying the snowstorm wouldn't happen because of a "south-based +NAO".

Well the La Nina is officially over now.. this latest Kelvin wave neutralizing the subsurface is what did it. It's interesting that when this happens, and the SOI spikes negative is when we will finally see a strong -PNA in the N. Pacific (5-21 to 5-25)

April and May have been above average.

I think it was a flip to more of a La Nina decadal state, because the PDO is water circulation in the North Pacific Ocean, and the Southern Hemisphere doesn't have the same water circulation... but there were High pressures on both sides of the ENSO Hadley Cell in the Northern and Southern Hemisphere's