Winter 2025-26

[bncho]

Is December looking less and less good (because it seems like the beginning of the month has trended warmer), or is it just models rushing the pattern change like usual?

[Stormchaserchuck1]

12 minutes ago, bncho said:

Is December looking less and less good (because it seems like the beginning of the month has trended warmer), or is it just models rushing the pattern change like usual?

The Pacific looks good with MJO going through Phase 7 and possibly Phase 8.. models are developing and have trended toward a +PNA pattern. The Atlantic was looking blocky earlier in the month and that was exciting because it was associated with a Stratosphere warming to help sustain the pattern until possibly early January. In the last few days a big +NAO appeared in the medium range, and the 10mb warmings doesn't look as strong, although it's still a Strat warming happening. We will probably get colder later in the month, but it kind of has a bad taste when the fundamentals were looking so good, now it's just a MJO-amped pattern and nothing more. By fundamentals I mean holding a -NAO for more than 10 days. 

[bncho]

7 minutes ago, Stormchaserchuck1 said:

The Pacific looks good with MJO going through Phase 7 and possibly Phase 8.. models are developing and have trended toward a +PNA pattern. The Atlantic was looking blocky earlier in the month and that was exciting because it was associated with a Stratosphere warming to help sustain the pattern until possibly early January. In the last few days a big +NAO appeared in the medium range, and the 10mb warmings doesn't look as strong, although it's still a Strat warming happening. We will probably get colder later in the month, but it kind of has a bad taste when the fundamentals were looking so good, now it's just a MJO-amped pattern and nothing more. 

Correct me if I'm wrong, but essentially what you're saying is that we’ll probably still get colder later in December, but the pattern is now looking less “textbook perfect” than it did before; it looks more like a pattern driven mainly by the MJO rather than a more powerful and sustained cold setup from both the Pacific and the Atlantic.

[frd]

7 minutes ago, Stormchaserchuck1 said:

The Pacific looks good with MJO going through Phase 7 and possibly Phase 8.. models are developing and have trended toward a +PNA pattern. The Atlantic was looking blocky earlier in the month and that was exciting because it was associated with a Stratosphere warming to help sustain the pattern until possibly early January. In the last few days a big +NAO appeared in the medium range, and the 10mb warmings doesn't look as strong, although it's still a Strat warming happening. We will probably get colder later in the month, but it kind of has a bad taste when the fundamentals were looking so good, now it's just a MJO-amped pattern and nothing more. 

Didn't Webb say the - NAO was going to lock in  ? 

[frd]

9 minutes ago, Stormchaserchuck1 said:

The Pacific looks good with MJO going through Phase 7 and possibly Phase 8.. models are developing and have trended toward a +PNA pattern. The Atlantic was looking blocky earlier in the month and that was exciting because it was associated with a Stratosphere warming to help sustain the pattern until possibly early January. In the last few days a big +NAO appeared in the medium range, and the 10mb warmings doesn't look as strong, although it's still a Strat warming happening. We will probably get colder later in the month, but it kind of has a bad taste when the fundamentals were looking so good, now it's just a MJO-amped pattern and nothing more. 

Warming events taking place at both the North Pole and the South Pole with assist the MJO in progressing into phase 8 in December.  

[frd]

Allan Huffman @RaleighWx   22m  

 

Well for all you #SSWE people out there. Today's 00z EPS showed all members (100%) showing a 10mb U wind reversal over the north pole around 11/28 to 11/29. The implications, are enhanced blocking risk in December and the possibility that the SPV will be further receptive to weakening later in the Winter which could influence the mid/late Winter.

 

[Stormchaserchuck1]

7 minutes ago, bncho said:

Correct me if I'm wrong, but essentially what you're saying is that we’ll probably still get colder later in December, but the pattern is now looking less “textbook perfect” than it did before; it looks more like a pattern driven mainly by the MJO rather than a more powerful and sustained cold setup from both the Pacific and the Atlantic.

Yeah it looks like it is MJO driven. The good news is the Pacific continues to act more like "Neutral ENSO" than La Nina. CPC PNA has been positive 21 of the last 29 months, and 12 of the last 19 months since the 23-24 El Nino ended. The 23-24 Strong Nino I believe changed something. I've watched it difficult for N. Pacific ridges to establish and sustain all year. ENSO does correlate the highest in Jan-Feb, but this is a pretty good +PNA now on models for the last week of Nov and early Dec... 

We had 8 straight +AO months earlier this year. We had 7 straight +NAO months until 2 months ago. The Atlantic side is not in a long term -NAO state, and it's decadal fluctuation index, so the consistency is important. That's why a good month of solid -NAO (2nd half of Nov in December) was looking good! Some change! It's kind of the same pattern happening. Maybe the Stratosphere warming will turn the NAO back negative in the 2nd half of December, but that's because of something, not a default state, which I was hoping for.

I still think we see -AO tendency this Winter because of low N. Hemisphere 500mb heights in the Summer and Fall. 

[Stormchaserchuck1]

7 minutes ago, frd said:

Didn't Webb say the - NAO was going to lock in  ? 

Did he? It was on models, now they have some pretty good +NAO troughing near Greenland with ridging underneath of it on the east coast. I think we are still below average temps though during the ridge because of -epo/+pna at the time. 

[Stormchaserchuck1]

4 minutes ago, frd said:

Allan Huffman @RaleighWx   22m  

You don't need a 500mb -NAO to have 10mb warming. Actually history is full of examples where the two are at odds. It correlates +40dm -NAO at Day+0, but a +100dm -NAO at ~+30 days (+25-35 days), which is the end of December. Let's see if we get a 2nd -NAO period later in Dec. 

[Stormchaserchuck1]

16 minutes ago, frd said:

Warming events taking place at both the North Pole and the South Pole with assist the MJO in progressing into phase 8 in December.  

Warming events don't happen in the Summer. You mean in June in the South Pole? 

[Terpeast]

1 hour ago, Stormchaserchuck1 said:

The Pacific looks good with MJO going through Phase 7 and possibly Phase 8.. models are developing and have trended toward a +PNA pattern. The Atlantic was looking blocky earlier in the month and that was exciting because it was associated with a Stratosphere warming to help sustain the pattern until possibly early January. In the last few days a big +NAO appeared in the medium range, and the 10mb warmings doesn't look as strong, although it's still a Strat warming happening. We will probably get colder later in the month, but it kind of has a bad taste when the fundamentals were looking so good, now it's just a MJO-amped pattern and nothing more. By fundamentals I mean holding a -NAO for more than 10 days. 

Which models/forecast periods are you looking at? 

[Stormchaserchuck1]

8 minutes ago, Terpeast said:

Which models/forecast periods are you looking at? 

https://www.meteo.psu.edu/ewall/ENSHGTAVGNH_6z/ensloopmref.html   0z EPS has the same thing. 

NAO is positive Thanksgiving until Dec 6. Now we have a good Pacific during that time, remember 13-14 and 14-15 had a favorable Pacific with +NAO and we did fine snow-wise. 

The Scan ridge is looking good at the end, but it's more reflecting the warming at 50mb and 10mb. 

 

[Terpeast]

3 minutes ago, Stormchaserchuck1 said:

https://www.meteo.psu.edu/ewall/ENSHGTAVGNH_6z/ensloopmref.html

NAO is positive Thanksgiving until Dec 6. Now we have a good Pacific during that time, remember 13-14 and 14-15 had a favorable Pacific with +NAO and we did fine snow-wise. 

The Scan ridge is looking good at the end, but it's more reflecting the warming at 50mb and 10mb. 

 

Oh I thought you were talking about the euro weeklies. I don't expect much from the nao until the SSW + scand ridging take effect and (hopefully) retrogrades over greenland

[Stormchaserchuck1]

1 minute ago, Terpeast said:

Oh I thought you were talking about the euro weeklies. I don't expect much from the nao until the SSW + scand ridging take effect and (hopefully) retrogrades over greenland

Hopefully it materializes. Probably not a given though.