2025-2026 ENSO

[Typhoon Tip]

17 hours ago, bluewave said:

The tendency has been more +PNA in July since 2013 with a strong 500 mb ridge in the East. Prior to this recent decade we usually had more of a -PNA when there was a strong ridge in the East. Have also been seeing more ridging in the East during the winters in the 2020s with + PNAs than we used to in the past. 
 

 

It's because the mean latitude of the westerlies/gradient is shifting N associated with CC.   A shift that's doing so on the scale of life time, not mere seasons...  So we don't really observe it year to year, but 15 or 20 years goes by and the jet axis are N of where they were... And idiosyncratic aspects emerge like like that where positive height anomalies cushion under the nadirs of the planetary wave spacings.   I've noticed this more and more so over the years... where the bottom of the L/W axis appear to be 'compressing a balloon' at time.

[bluewave]

23 minutes ago, Typhoon Tip said:

It's because the mean latitude of the westerlies/gradient is shifting N associated with CC.   A shift that's doing so on the scale of life time, not mere seasons...  So we don't really observe it year to year, but 15 or 20 years goes by and the jet axis are N of where they were... and idiosyncratic aspects emerge like positive heights under the nadirs of the planetary wave spacings.   I've noticed this more and more so over the years... where the bottom of the L/W axis appear to be 'compressing a balloon' 

Yeah, I was just discussing this shift across the seasons a few days ago. The mid-latitude ridge from Japan across the U.S. to Europe has been a new dominant player since the 18-19.

This has lessened the influence of the usual higher latitude teleconnections like the WPO, EPO,PNA,AO, and NAO. So we have been getting strong Southeast ridge  patterns even with -EPO,+PNA, -WPO,-AO, and -NAO. 

It essentially forces the winter storm track further north through the Great Lakes. So in February we had our first -5 -AO result in a strong cutter leading to the record snows in Toronto and Montreal instead of the typical KU storm track. 

We also saw the -EPO +PNA merger back in December with the mid-latitude ridge leading to the 4th warmest December on record in the CONUS with what used to be colder teleconnections when this mid-latitude ridge was absent in the past. 

During January the 850 mb cold pool was at the smallest on record. So what used to be very cold telconnections in the past were much milder than past instances with similar higher latitude teleconnections.

I also posted the other day on how we just set a new all-time July record 500 mb height record from Japan to Europe along 40N to 50N. This is why the Southeast ridge was the strongest on record for July even with a strong -EPO and +PNA block on the Pacific side.

Past instances of such a strong ridge in the East had more of a -PNA and weaker blocking near Alaska than we have been seeing over the last decade.

So this new mid-latitude ridge is becoming its own teleconnection leading to new combinations of 500mb patterns that we used to get before 18-19. 

 

 

[40/70 Benchmark]

It will be interesting to see how strong the SE ridge is when we manage to get a robust -AO/NAO/EPO/WPO, +PNA combo. My guess is there won't be one.

[Stormchaserchuck1]

January on the Euro seasonal looks like -EPO/-AO

[40/70 Benchmark]

1 hour ago, Stormchaserchuck1 said:

January on the Euro seasonal looks like -EPO/-AO

I understand the limitations of these data at this range, but I don't disagree.