2025-2026 ENSO

[bluewave]

1 minute ago, 40/70 Benchmark said:

IDK, seems kind of arbitrary to me, dude....pretty close to last year's 2.762. Furthermore, phase 4 is also in the MC. You do you, but I would be loathe to forecast a strong RNA in the mean. Again, agree weaker than last year's deviation, which isn't saying much.

I am going weaker on the PNA than last winter. But there could still be +PNA intervals. Very strong warmth and 500mb ridging in Canada since May 2023. 

 

[40/70 Benchmark]

21 minutes ago, bluewave said:

I am going weaker on the PNA than last winter. But there could still be +PNA intervals. Very strong warmth and 500mb ridging in Canada since May 2023. 

 

Well, regardless of the semtnics of the MJO criteria, we agree on that general point.

[MJO812]

[bluewave]

3 hours ago, 40/70 Benchmark said:

2021-2022 was actually our one repreieve from the seasonal +WPO.

It’s been a challenge maintaining strong enough 500mb blocking across the WPO, EPO, PNA, and TNH regions. The last time we pulled this feat off was January 2022. Last winter the block kept getting undercut and eroded from the very fast Pacific Jet sending shortwaves through. So this continued the Great Lakes cutter, I-78 to I-84 hugger, and suppressed Southern Stream storm tracks.

[Stormchaserchuck1]

3 minutes ago, bluewave said:

It’s been a challenge maintaining strong enough 500mb blocking across the WPO, EPO, PNA, and TNH regions. The last time we pulled this feat off was January 2022. Last winter the block kept getting undercut and eroded from the very fast Pacific Jet sending shortwaves through. So this continued the Great Lakes cutter, I-78 to I-84 hugger, and suppressed Southern Stream storm tracks.

We've had a good amount of PNA blocking (-PNA). December 2021 shattered records in this regard. 

-NAO's have not sustained at all. 15 days or less then it always goes back to neutral or positive, since I think 11-12. The 60s and 70s were not like that at all. EPO has also come in short periods, but that is more typical of the region to be like that than the NAO. 

[40/70 Benchmark]

6 minutes ago, Stormchaserchuck1 said:

We've had a good amount of PNA blocking (-PNA). December 2021 shattered records in this regard. 

-NAO's have not sustained at all. 15 days or less then it always goes back to neutral or positive, since I think 11-12. The 60s and 70s were not like that at all. EPO has also come in short periods, but that is more typical of the region to be like that than the NAO. 

I think the predominate MC forcing constructively interferes there, whereas it decontructively interferes with +PNA in conjunction with the enhanced Pac jet.

[Stormchaserchuck1]

Some long range confusion on the long range GEFS right now. It's the only model that has a strong MJO Phase 7 wave occurring

But it's developing a -PNA look

You guys are keeping track of this more than I am.. Has strong Phase 7 in late November been hard to happen the last several years? 

[40/70 Benchmark]

30 minutes ago, Stormchaserchuck1 said:

Some long range confusion on the long range GEFS right now. It's the only model that has a strong MJO Phase 7 wave occurring

But it's developing a -PNA look

You guys are keeping track of this more than I am.. Has strong Phase 7 in late November been hard to happen the last several years? 

November 2024 was moderate strong and 2023 was stronger.

[GaWx]

6 hours ago, brooklynwx99 said:

wow, the ECMWF is super aggressive with the weakening of the SPV early on. can't remember the last time i've seen a SPV potentially this weak to start a winter

 The mean gets down to a mere +10, which compares to +14-15 on the prior run and +18 on several runs before that! I estimate 35-40 % of members with a very early season major SSW (10 mb wind reversal), by far the highest yet!

 Here’s a 3 run animation showing the weaker SPV trend:

 

 The last times late Nov/early Dec was this weak were 2009-10, 2000-1, and 1996-7 with 2016-7 almost as weak.

 The last time there was an actual major SSW (reversal) in late Nov or early Dec was way back on 12/7/1987! The last time there was one at any point in Nov or Dec was on 12/29/2001. Before that there was 12/16/1998, the aforementioned 12/7/1987, the legendary 12/31/1984, 12/3/1981, 11/24/1968, 12/7/1965, and 11/30/1958.
 
 So, it having been a whopping 24 years since the last Nov or Dec major SSW means we’re extremely overdue. Prior to the current 24 year drought, the longest on record between early season majors was 13 years followed by 11 years. The current average return period is 8 years.

 Regarding these 8 early major SSWs, how many were after allowing for a lag period followed by a notable long cold period in a good portion of the E US?

-12/29/2001: no notable cold

-12/16/1998: cold 1-3 weeks later

-12/7/1987: cold 3-6 weeks later including intense cold 4-5 weeks later

-12/31/1984: cold 2-6 weeks later including extreme cold 3 weeks later

-12/3/1981: cold 1-7 weeks later including extreme cold 5 weeks later

-11/24/1968: cold 2-7 weeks later

-12/7/1965: cold 5-9 weeks later including extreme cold 7 weeks later

-11/30/1958: cold 1-6 weeks later

 So, 7 of the 8 early season major SSWs were followed by cold domination starting mainly 1-3 weeks later and lasting for 2-6 weeks with a one week period of intense cold in 1/2 the cases.

[Stormchaserchuck1]

13 minutes ago, GaWx said:

 The mean gets down to a mere +10, which compares to +14-15 on the prior run and +18 on several runs before that! I estimate 35-40 % of members with a very early season major SSW (10 mb wind reversal), by far the highest yet!

 Here’s a 3 run animation showing the weaker SPV trend:

 The last times late Nov/early Dec was this weak was 2009-10, 2000-1, and 1996-7 with 2016-7 almost as weak.

 The last time there was an actual major SSW (reversal) in late Nov or early Dec was way back on 12/7/1987! The last time there was one at any point in Nov or Dec was on 12/29/2001. Before that there was 12/16/1998, the aforementioned 12/7/1987, the legendary 12/31/1984, 12/3/1981, 11/24/1968, 12/7/1965, and 11/30/1958.
 
 So, it having been a whopping 24 years since the last Nov or Dec major SSW meaning we’re extremely overdue. Prior to the current 24 year drought, the longest on record between early season majors was 13 years followed by 11 years. The current average return period is 8 years.

 Regarding these 8 early major SSWs, how many were after allowing for a lag period followed by a notable long cold period in a good portion of the E US?

-12/29/2001: no notable cold

-12/16/1998: cold 1-3 weeks later

-12/7/1987: cold 3-6 weeks later including intense cold 4-5 weeks later

-12/31/1984: cold 2-6 weeks later including extreme cold 3 weeks later

-12/3/1981: cold 1-7 weeks later including extreme cold 5 weeks later

-11/24/1968: cold 2-7 weeks later

-12/7/1965: cold 5-9 weeks later including extreme cold 7 weeks later

-11/30/1958: cold 1-6 weeks later

 So, 7 of the 8 early season major SSWs were followed by cold domination starting mainly 1-3 weeks later and lasting for 2-6 weeks with a one week period of intense cold in 1/2 the cases.

There is a really strong timelag between Stratosphere warming and -NAO at different times of the year:

Nov 1-15: +45 days

Nov 15-30: +40 days

Dec 1-15: +35 days

Dec 15-30: +30 days

Jan 1-15: +25 days

Jan 15-30: +25 days

Feb 1-28: +20 days

March 1-31: +15 days

Cold Stratosphere has a +0-day timelag to corresponding +NAO at all times of the cold season. 

[donsutherland1]

2 hours ago, MJO812 said:

In other words, things seem to be moving toward a vintage fast start to winter as is often, though not always, the case during La Niña winters.