2025-2026 ENSO

[stadiumwave]

4 hours ago, PhiEaglesfan712 said:

Previous years with similar ENSO/IOD/PDO patterns. They tend to have cool Decembers, but torch in January and February.

Actually not the -QBO years with anykind of early strat warming. JAN is the coldest in that analog package. Will not be this year but just saying. 

[BlizzardWx]

1 minute ago, GaWx said:

 The 12/13/25 WPO of -348 is the most negative WPO on any day in December since 12/25/1996!

 The only Decembers since 1948 with at least one day lower than -348 are:

1996, 1989, 1983, 1977, 1966, 1955

I've been trying to think about what is "going wrong" with such a prolific -WPO to be talking about record warmth down my way. Do you know if a -WPO is typically good for the southern Plains? Is it perhaps atypical to have a -WPO paired with a -PNA or is that typical? I know when I look at the current pattern it seems reasonable to have a west coast trough downstream of that high but maybe sometimes ridging extends further southeast? 

Mostly just trying to build my understanding for this index. 

[GaWx]

 Well, as of Dec 13th, the MJO still hasn’t returned to phase 8! It was in 8 only Dec 3rd-7th. Dec 8th-13th have all been in very weak (essentially neutral) phases 5-7. I still think it has a good chance to get back into 8 very soon, but we’ll see:

[PhiEaglesfan712]

3 hours ago, bncho said:

Genuinely curious--could you provide some examples?

The most obvious ones are the most recent: 2016-17 and 2022-23.

2 hours ago, MJO812 said:

Nothing

I have a hard time seeing a torch in January and February with a neutral enso going into el nino.

In case you forgot, here's what happened the last time a dissipating la nina led into an el nino:

[GaWx]

1 hour ago, BlizzardWx said:

I've been trying to think about what is "going wrong" with such a prolific -WPO to be talking about record warmth down my way. Do you know if a -WPO is typically good for the southern Plains? Is it perhaps atypical to have a -WPO paired with a -PNA or is that typical? I know when I look at the current pattern it seems reasonable to have a west coast trough downstream of that high but maybe sometimes ridging extends further southeast? 

Mostly just trying to build my understanding for this index. 

 I’ll check now for December. These 9 were solidly -WPO Decembers dominating throughout the entire month:

2013, 2010, 2009, 2005, 1995, 1989, 1980, 1961, and 1956. Of these:

 

1) Cold in the S Plains?

2013, 2009, 2005, 1989, 1961

 

2) Near normal S Plains?

2010, 1995

 

3) Mild S Plains?

1980, 1956

 

 So, strong -WPO Decembers leaned somewhat to the cold side in the S Plains, but only 5 of 9 averaged cold. It looks like this year may end up averaging near normal based on a cold 1st half and mild 2nd half. But we’ll see.

 

PNA for these 9 Decembers:

2013: moderate -PNA

2010: strong -PNA

2009: weak +PNA

2005: strong +PNA

1995: moderate +PNA

1989: moderate +PNA

1980: weak -PNA

1961: strong -PNA

1956: weak -PNA

 

 So, PNA for these solidly -WPO Decembers is very mixed.

[snowman19]

7 hours ago, GaWx said:

 The 12/13/25 WPO of -3.48 is the most negative WPO on any day in December since 12/25/1996!

 The only Decembers since 1948 with at least one day lower than -3.48 are:

1996, 1989, 1983, 1977, 1966, 1955

The 1989-90 winter saw what was probably the biggest complete pattern flip in the last 50+ years. We went from a record cold arctic ice box from November through the end of December, then there was a big cutter on New Year’s Eve and a light switch flip to a full on torch for all of January and February 

[EasternLI]

Two clusters on eps cluster analysis in the long range last night. -NAO of unknown impact the general idea. There is a road in some analogs where we start January with a -NAO and as we lose that, the PNA goes positive. Could we take that road this year?

[40/70 Benchmark]

8 hours ago, GaWx said:

 The 12/13/25 WPO of -3.48 is the most negative WPO on any day in December since 12/25/1996!

 The only Decembers since 1948 with at least one day lower than -3.48 are:

1996, 1989, 1983, 1977, 1966, 1955

All 6 of those seasons finished with a mean DM -WPO, so this season should, too....though we could have a month or two average +WPO, as was the case in 1990. Looks like I am going to be off on the WPO again...it's so tough to forecast. At least I didn't go strongly positive....

[40/70 Benchmark]

7 hours ago, PhiEaglesfan712 said:

The most obvious ones are the most recent: 2016-17 and 2022-23.

In case you forgot, here's what happened the last time a dissipating la nina led into an el nino:

2016-2017 lead into another La Nina...not an El Nino.

I don't think that really has any value here, aside from the fact that February will often bias the Jan-Feb period warm in the east in a La Nina. 2022-2023 was a deeply +WPO/-PNA season, and I'm quite certain that won't be the case this season. Doesn't mean the second half will necessarily be great, but I don't think much can be gleaned from that particular composite.

[40/70 Benchmark]

8 hours ago, stadiumwave said:

Actually not the -QBO years with anykind of early strat warming. JAN is the coldest in that analog package. Will not be this year but just saying. 

I will be surprised if we don't see a major SSW and full reversal later this season.

[EastonSN+]

9 hours ago, GaWx said:

 The 12/13/25 WPO of -3.48 is the most negative WPO on any day in December since 12/25/1996!

 The only Decembers since 1948 with at least one day lower than -3.48 are:

1996, 1989, 1983, 1977, 1966, 1955

3 good and 3 bad winters snowfall wise. Nice even split.

[40/70 Benchmark]

34 minutes ago, EastonSN+ said:

3 good and 3 bad winters snowfall wise. Nice even split.

I would take 1996 and run relative to what I have had recently...December was nice, and had an early April event for the ages.

[GaWx]

1 hour ago, 40/70 Benchmark said:

All 6 of those seasons finished with a mean DM -WPO, so this season should, too....though we could have a month or two average +WPO, as was the case in 1990. Looks like I am going to be off on the WPO again...it's so tough to forecast. At least I didn't go strongly positive....

 

57 minutes ago, EastonSN+ said:

3 good and 3 bad winters snowfall wise. Nice even split.

 Thanks. That’s based on my 1st list, which is of those Decembers that had 1+ days dipping lower than -3.48. But those Decembers didn’t necessarily have a solid -WPO dominating through the entire month. One of those Decembers, 1996, actually averaged a +WPO overall. Also, 1983 and 1977 didn’t average a negative enough WPO. And there were a bunch of Decs left out of that 1st list that had a very -WPO with it dominating throughout but that didn’t have at least one day dip below -3.48 like 2013, 2010, 2009, 1995, 1980, 1961, and 1956 that make them good -WPO Dec analogs.

 OTOH, the 2nd list included some that weren’t -ENSO through the winter or at all like 2009, 1989, 1980, and 1956. In addition, 2005 and 1995 had a moderate or strong +PNA in Dec.

 So, what are we left with for the best analogs based on solid -WPO throughout Dec, -ENSO through the winter, and a moderate to strong -PNA in Dec? 2013, 2010, and 1961. Of these three, the PNA flipped to positive in Jan in 2014 and 2011 and to neutral in Jan of 1962.

  So, the closest -ENSO/Dec -WPO/Dec -PNA analogs are 2013, 2010, and 1961.

[EastonSN+]

26 minutes ago, GaWx said:

 

 Thanks. That’s based on my 1st list, which is of those Decembers that had 1+ days dipping lower than -3.48. But those Decembers didn’t necessarily have a solid -WPO dominating through the entire month. One of those Decembers, 1996, actually averaged a +WPO overall. Also, 1983 and 1977 didn’t average a negative enough WPO. And there were a bunch of Decs left out of that 1st list that had a very -WPO with it dominating throughout but that didn’t have at least one day dip below -3.48 like 2013, 2010, 2009, 1995, 1980, 1961, and 1956 that make them good -WPO Dec analogs.

 OTOH, the 2nd list included some that weren’t -ENSO through the winter or at all like 2009, 1989, 1980, and 1956. In addition, 2005 and 1995 had a moderate or strong +PNA in Dec.

 So, what are we left with for the best analogs based on solid -WPO throughout Dec, -ENSO through the winter, and a moderate to strong -PNA in Dec? 2013, 2010, and 1961. Of these three, the PNA flipped to positive in Jan in 2014 and 2011 and to neutral in Jan of 1962.

  So, the closest -ENSO/Dec -WPO/Dec -PNA analogs are 2013, 2010, and 1961.

Such a small dataset. 1961/1962 was the only dud.

All three years embedded in the 2 epic snowfall periods (1955 to 1969 and 2000 to 2018).

 

[JenkinsJinkies]

1 hour ago, 40/70 Benchmark said:

2016-2017 lead into another La Nina...not an El Nino.

I don't think that really has any value here, aside from the fact that February will often bias the Jan-Feb period warm in the east in a La Nina. 2022-2023 was a deeply +WPO/-PNA season, and I'm quite certain that won't be the case this season. Doesn't mean the second half will necessarily be great, but I don't think much can be gleaned from that particular composite.

Also 16-17, 22-23 had no measurable December snow in the DC and Baltimore area airports. Very much not the case this year.

[GaWx]

3 minutes ago, JenkinsJinkies said:

Also 16-17, 22-23 had no measurable December snow in the DC and Baltimore area airports. Very much not the case this year.

Also, Dec of 2016 had a +WPO and Dec of 2022 had a neutral WPO fwiw.