Stormchaserchuck1

I think that as long as we keep repeating this Summer pattern of +AO, that has been so common since 2013, the Winter NAO will have a tendency to positive, and probably PNA-negative, WPO-positive as well. Big +AO on models through the 2nd week of June. This is the same pattern as the last 12 years:

Thanks for the roll back bluewave! The thing that I hated most about the 09-10 storms is that it warmed up in between them. I always fantasized a 6'+ stacked snowfall, but while close they did melt a lot in between.

I think this is so interesting - I've talked before about ENSO subsurface trends, and how it correlates with the N. Hemisphere pattern more than ENSO SSTs, OLR, 850mb winds, etc. Now, we are currently getting a healthy Kelvin wave that has changed the central-ENSO-subsurface in a few weeks from -1c to about +2-3c. Now, we have a strong +AO - about as strong as it's going to get at this time of the year. I rolled that forward to the following Winter, and got an El Nino-like pattern of a warm December, followed by a cold February The STJ pattern currently projected looks like El Nino for the next 3-4 weeks All this while a strong Kelvin Wave is warming the central-ENSO-subsurface in now-time. I've said before that the effects of such a happening are immediate - see how these El Nino aspects are happening around this coherent wave? It happens that way quite often.

Strong +AO for the next 2 weeks should keep Arctic Summer Ice melt relatively below normal to start the season, compared to the last 15 years. Lots of cold 500mb anomalies over the Arctic circle.

All this stuff about the "Pacific firehose near Japan" is linked to the WPO, and positive phase of that index.

+WPO has been linked to Indian Ocean warming. Indian Ocean SST patterns may be decadal, although the long term trend is generally up.

It was strong -QBO, too, which goes with El Nino for Stratosphere warming

7-day code red in the E. Pacific

The AMO may have an imapact: -AMO ibb.co/bR3LvKW+AMO ibb.co/KctZCPm-AMO ibb.co/wKX4YCC+AMO ibb.co/sFSwm0j I don't know what the numbers are at 40N.. Maybe it is +3F. +WPO flexes the SE ridge further north when coupled with -PNA, and as Ray pointed out it has been positive every Winter but 1 since 16-17 I don't think that we are seeing more of a SE ridge because of global warming. I think that whatever the global temperature increase is divided by latitude is what that impact is.

I'm tired of global warming being blamed for the Winter SE ridge, especially during -AO/-NAO periods, when the Pacific has been in +WPO/-PNA. This map makes sense to me in regard to those 2 patterns and downstream effects. Global warming makes a +2F overall difference, but that's about it. It's not some unicorn pattern that is causing new things, like a more impactful SE ridge. There is meteorology involved, everything that happens has a reason. The global warming effects are global, but not localized.

That map is the SST profile May-July that leads the Winter WPO.. positive phase, although it has correlated with -PDO more so in the last 8 years.

Not according to this https://www.longpaddock.qld.gov.au/soi/

Maybe active, but that data says not hyperactive. In the far east Atlantic there is somewhat of a -NAO tripole.. Maybe enhancing Cape Verde area.

Check this out Ray.. PDO and SSTs across the Tropical Pacific to Indian Ocean in May-July clearly lead it

A big part of the "heatwave near Japan" has kept the WPO + It doesn't just effect the PNA.

^Clear Atlantic tripole there. I found that this is the Apr-May SLP anomaly of our most active seasons since 1995 minus least active seasons since 1995 So far we have somewhat of an opposite pattern

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.