2026-2027 El Nino

[Stormchaserchuck1]

3 hours ago, Terpeast said:

So your analog is showing a huge aleutian low with a ridge over the rockies (again). How does it look over the polar domain though? If we get a -WPO/-EPO or -NAO along with that aleutian low, we just might avoid a wall to wall torch. If we get a well-timed STJ wave with cold air lurking nearby, we could score and big.

The general tendency is -H5 near the Poles, with +H5 in the mid-latitudes, but it's a pretty weak correlation (0.10-0.15) that far out. I've run several individual cities record breaking warm patterns out at different times, and that's what the constant theme is (warm mid-latitudes, -h5 near the Pole +several months time). 

[cbmclean]

3 hours ago, GaWx said:

 Even if RONI ends up peaking +1.5+, the DC area could still have a BN averaged winter based on the 2009-10, 1965-6, and 1957-8 analogs. What did these 3 analogs have in common? -NAO and -AO, both of which were lacking in nearly all of the other +1.5+ ENSO winters. It wasn’t the Pacific that made the difference as they almost always had +PNA and no -EPO/-WPO for all +1.5+ ENSO.

 So, a -NAO/-AO would appear to be the deciders. The major challenge though for getting a -NAO is going to be sunspots almost for sure still not getting down to low (say, sub 35/month). There hasn’t been even one -NAO winter since 1980 with a >35 sunspot avg! So, the odds would be heavily against a cold DC area winter should ENSO get to +1.5+. In that case, the best hope would be for a NN instead of mild DC winter. Your better hope for a cold winter would as you’d suspect be for a sub +1.5 RONI peak this fall/winter.

What is the hypothesized physical mechanism of causation between sunspots (or solar cycle in general) and high latitude blocking?

[cbmclean]

11 hours ago, Stormchaserchuck1 said:

Sorry to dwell on the Winter West Coast ridge again, but this really stands out to me as an extreme anomaly

Most extreme West Coast DJF ridge analogs

The news is, the ridge really sticks around +time in analog cases.. this is the following year:

March (not included in my visual analog picks.. yet almost as strong of an anomaly!)

April (+60dm over the SW, US is extreme!)

May

Summer (June-August)

Following Winter (26-27 analog)

^75% of the N. Hemisphere is +H5 in the following Winter, which fits a warming sequence possibly associated with El Nino. The main point is just the skew warm-general +time. 

This is the mid-latitudes the following Winter (26-27 analog)

Winter PNA DJF 25-26 was negative, so interesting that they got a #1 record warm Winter on the West coast. Monthly PNA:

-1.41
2026   0.79  -0.56

How is it possible for there to be a -PNA with that much of a western ridge?  What exactly is the definition of the PNA index?

[Winter Wizard]

1 hour ago, cbmclean said:

How is it possible for there to be a -PNA with that much of a western ridge?  What exactly is the definition of the PNA index?

It's a bit of a misconception that the PNA corresponds to a western US ridge/trough, the index actually corresponds to a much broader area per the CPC:

PNA = Z*(15°N-25°N,180-140°W)-Z*(40°N-50°N,180-140°W) +Z*(45°N-60°N,125°W-105°W)-Z*(25°N-35°N,90°W-70°W)

So in the case of December, the -PNA was mostly the result of strong troughing over western Canada, which in turn torched the Southwest US. Good reminder that the number isn't the be all, end all, you have to look at the bigger picture. 

 

[GaWx]

2 hours ago, cbmclean said:

What is the hypothesized physical mechanism of causation between sunspots (or solar cycle in general) and high latitude blocking?

I don’t know, but I believe others here can explain it.

[LakePaste25]

1 hour ago, Winter Wizard said:

It's a bit of a misconception that the PNA corresponds to a western US ridge/trough, the index actually corresponds to a much broader area per the CPC:

PNA = Z*(15°N-25°N,180-140°W)-Z*(40°N-50°N,180-140°W) +Z*(45°N-60°N,125°W-105°W)-Z*(25°N-35°N,90°W-70°W)

So in the case of December, the -PNA was mostly the result of strong troughing over western Canada, which in turn torched the Southwest US. Good reminder that the number isn't the be all, end all, you have to look at the bigger picture. 

 

 

The reverse of this also exists. A nino-style pacific jet extension that blasts warm air into Canada and the E US typically correlates to a weak +PNA.