GaWx

 On 12/26/21, when the PNA had been negative all month/way down at -1.8 that day and Baltimore (among others) had just had a miserably mild 68F Christmas high with very mild to continue through New Year’s, this (see image below) was the 12/26/21 GEFS two week PNA forecast, which went to 1/9/22: still down at -0.6 on 1/9/22 and no clearcut sign that 1/9/22 was going to be the start of a 38 day long +PNA as well as Jan ending up the snowiest month by far there since Jan of 2016 along with it being the coldest month since Jan of 2018:

@donsutherland1

*Edit: The main points are:
- The models can’t see out that far with notable skill and that includes forecasting the PNA/general patterns
- -ENSO -PNA Decembers since 1984 all transitioned to +PNA Jans

13 minutes ago, SnowGoose69 said:

00 and 97 I think also went pretty strong +PNA I think but can’t recall if they were negative in December or not.  I want to say they were not 

-Actually, Dec of 1996, indeed, was still another -ENSO strong -PNA that transitioned to a +PNA in Jan after a 1.8+ rise.

-Dec of 1999 had a neutral PNA. So, that isn’t in this group.

*Corrected for typo…Dec of 1999

1 hour ago, donsutherland1 said:

While the AO and NAO are looking good on the latest GEFS, the PNA is not.

 I’m very curious to see what happens in Jan with the PNA based on -ENSO strong Dec -PNA analogs like 2021, 2013, 2010, 2008, and 1984 whose Jan PNA all rose 1.8++ from Dec. That’s still well beyond what models can see with any notable degree of skill. My GEFS PNA forecasting images for Dec 2021-Jan 2022 displayed that well.

16 minutes ago, EastonSN+ said:

 Yeah, way out in fantasyland! This reminds me of this Euro storm from last January in not as far out fantasyland:

  
 While this was gone on the very next run, this turned out to be when the historic 1/21-2/2025 Gulf coast/deep SE winter storm occurred.

30 minutes ago, donsutherland1 said:

In general, a PNA- pattern results in lighter snowfalls in the New York City area and northern Mid-Atlantic. The Boxing Day blizzard is a notable exception and the only KU snowstorm during December when the PNA was negative.

Hey Don,

 This is somewhat related and something I happened to compile yesterday about big NC snowstorms during -PNAs. First, note that the -PNA for the 2010 storm was only weak (-0.3). Also, what’s interesting about the list below of big NC snows during a -PNA is that only one of the 7 most -PNA 6”+ storms there were during a -NAO! Anyone know why or is this likely just from randomness? It’s a somewhat decent sized sample of 7 and 4 of the 7 had a moderate to strong +NAO as opposed to just a weak +NAO:

6”+ storms since 1950 at GSO and/or RDU: most negative PNA:

-1.1: 2/12-13/2014 (moderate +NAO)
-0.8: 1/22-24/1954 (moderate +NAO)
-0.8: 3/2-3/1960 (neutral NAO)
-0.7: 1/6-7/2017 (moderate +NAO)
-0.5: 3/9/1960 (neutral NAO)
-0.3: 12/26/2010 (moderate -NAO)
-0.3: 2/24-26/2015 (strong +NAO)

Daily PNA:

Daily NAO:

 The -NAO continues to be very strong for late this month per the 0Z GEFS and EPS:

8 hours ago, WestCentrlVA said:

Not saying it's right but the 0z euro run would make many happy if it actually happened. Long duration event for sure. 

 This Euro storm reminds me of another at 9-10 days out released on 1/12/25 that caused social media to get way out of control and even caused me to be texted in the middle of the night from an Atlanta friend due to his Facebook feed from this as if it were credible:

 But this did turn out to be when the historic Gulf coast/deep SE winter storm occurred (1/21-22/2025).

Ladies and gentlemen, can I have your attention, please? The results are in and we did it. The MJO went back into phase 8 on Dec 15th, the coldest day of the season to date! Let the celebrations begin! The weenies are gonna party like it’s Feb 1899!

 Natural gas closed up nearly 4%, easily its best day since Dec 5th. This is largely based on today’s forecast speculation that the forecasted dominant warmth may not be as widespread, intense, and/or long lasting in the E US as thought yesterday thanks largely to the newly forecasted strong -NAO.

 The model consensus is currently forecasting the strongest -NAO on Christmas as well as surrounding days since way back in 2010! In stark contrast, these 6 had a strong +NAO: 2011, 13, 15, 16, 23, and 24.

12Z GEFS strong -NAO that starts in just 5 days (12/22) and is the strongest -NAO for days 5-16 averaged out on any GEFS run back to at least Oct 31st:

Compare this to the 0Z 12/12/25 run: 12/22-28 were 0 to +0.5 instead of -1 to -2

 Check out the widespread much lower H5 for nearly the entire E US on the 12Z GEFS vs the 6Z GEFS as of 0Z 12/30 helped mainly by the apparently even stronger -NAO:

These images show that the GEFS was too slow in showing the transition from the very strong -PNA of Dec 2021 to the strong +PNA of Jan of 2022:

 12/15/21 GEFS PNA forecast was ok

 

But the 12/26/21 GEFS PNA forecast, which goes through 1/9/22, had all members 0 to -2 for then. The actual 1/9/22 ended up being +0.2. So, it was too slow in predicting the turn to a +PNA:

12/31/21 GEFS PNA forecast out to 1/14/22: finally turned to +PNA but not positive enough as 1/14 was actually +0.7 vs this forecast for ~+0.4:

1/5/22 GEFS PNA forecast out to 1/19/22: not positive enough as 1/19 was actually +1.0 vs this forecast for only ~+0.1:

This shows the actuals for the entire Dec-Jan 2021-2:

 Is NG finally bottoming? It’s currently up over 3%. If this were to hold, this would be the best day since Dec 5th, the day it peaked. There’s been only one other up day since then, Dec 9th, when it closed up 1/2% and then was followed by more big down days as the maps kept insisting on warmth dominating the US.

 Why do I think it’s up today? The AO and especially the NAO forecasts have gotten significantly more negative than yesterday’s more neutral forecasts as per my post three above this. A strong -NAO lead to much colder 0Z and 6Z GFS after Christmas fwiw. This kind of thing with the -NAO/-AO happened early this month. 

 From NOAA, one can see how much the NAO has dropped since just yesterday on the GEFS:

Yesterday’s GEFS NAO (12/16);

Today’s GEFS NAO (12/17): note the biggest changes are for 12/22-26, only 5-9 days out. Yesterday they were ~0 while today they’re -0.7 to -1.0:

1 hour ago, MJO812 said:

Not the eps and gfs.

Here’s the 0Z GEFS NAO: week 2 of this and the EPS for the mean (green line) have gotten much more negative just since 24 hours earlier and are now close to the strongest -NAOs of all runs at least since Oct 31st per WxBell’s history that goes back that far: look at green line

24 minutes ago, Stormchaserchuck1 said:

Yeah, it neutralizes. If you start from the most extreme point, it should come toward evening out. Still, ENSO is a powerful factor so I would have thought the +PNA January's would be more extreme. 6/7 were +PNA January's though, and since 1980, 5/5 were +PNA January's. It neutralizes the other side/point. Still, a net neutral signal in January-ENSO is something. Will be interesting to watch and see how this January evolves, I do know that Natural Gas led these Euro weeklies and all this warm stuff for Jan by some time! 

Chuck,

 The strongest Jan +PNAs for +ENSO were these:

1977: +1.8 from +0.5 in Dec

1983: +1.2 from +0.8 in Dec

1987: +1.0 from +1.4 in Dec

1992: +1.3 from +0.5 in Dec

2003: +1.3 from +1.6 in Dec

2010: +1.3 from +0.3 in Dec

2016: +2.0 from +0.8 in Dec

 
 So, avg Dec preceding +1+ +ENSO Jan PNA was +0.8. But avg Jan following +1+ +ENSO Dec PNA was only +0.5 though it was skewed by 1954.

7 minutes ago, Stormchaserchuck1 said:

Hey Larry, 

All of your examples 1950-1980 were -PNA January. Then you have only 7 examples after 1980.. now 7/7 is a strong point, I agree, but it might be in the field of random if you consider what ENSO is/does. A good test would be the opposite: What did January do in +ENSO after a +PNA December? What there a difference 1950-1980 and after 1980 (I haven't run the data, but will say probably not - just guessing). My map in the last post includes that, so since it rolls forward to a pretty strong N. Pacific ridge in January, I'm thinking it probably doesn't check out the other way around: (does +PNA Dec lead to -PNA Jan in +ENSO?).

Chuck,

 Let’s see. I’m looking now at +ENSO 1+ PNA Decembers to Januaries: there were 8 cases:

- 1953-4 +1.3 to -1.1: drop of 2.4

- 1963-4 +1.8 to +0.2: drop of 1.6

- 1969-70 +1.8 to +0.6: drop of 1.2

- 1986-7 +1.4 to +1.0: drop of 0.4

- 1997-8 +1.2 to +0.7: drop of 0.5

- 2002-3 +1.6 to +1.3: drop of 0.3

- 2006-7 +1.9 to +0.7: drop of 1.2

- 2023-4 +1.2 to +0.5: drop of 0.7

- avg drop 1.0

- avg drop much higher for 1st 3 cases (1.7) vs last 5 (0.6)

———— 
Your thoughts?

23 minutes ago, Stormchaserchuck1 said:

I don't really get this "negative ENSO turned -PNA to +PNA" since 1980 thing. 

1. Why does it only start in the 1980s? Data was not unreliable before then, so it's not like you're starting from a blank point. I think a lack of examples increases the odds of random. If it didn't work before 1980, that's telling, not an ignored difference.

2. That's not what Negative ENSO does. Negative ENSO does not support a +PNA in January. The Hadley cell is extended in the N. Pacific in La Nina more often than not, and that supports -PNA. 

Since we are having such a strong -PNA December, here is a fun roll forward. This is what 500mb January looks like after -PNA Dec.. this is a total composite of 73 years, both - and + signs considered, going back to 1948:

That's an Aleutian ridge in the mean for January. But the ridge is a little further NE, which makes January a cold month for a lot of the US. 

The reason why it will sometimes switch is the MJO runs if 45-day cycles and Kelvin and Rossby waves sometimes run in 45-60 day cycles. We don't have a strong phase of those things now -- it will be interesting to see if we do go more +PNA after the 1st week of January. I think you are discovering a high mathematical random skew. 

Hey Chuck,

 Here’s a post I made on Friday going all of the way back to 1950 that shows that for some reason (possibly randomness) the sharpest rises from a sub -1 PNA Dec to Jan have occurred since 1984-5 (CC related?):

“This implies the realistic chance for a sub -1 Dec PNA. Whereas that’s bad news for those wanting E US cold in the 2nd half of Dec in the MidAtlantic/OH Valley south, it isn’t necessarily bad news for January prospects. That’s because in the vast majority of cases for -ENSO, the PNA in January rose sharply from Dec:

PNA Dec/Jan for -ENSO for strongly -PNA in Dec

- 1955-6: -2.1/-1.3 (rose 0.8)

- 1961-2: -1.2/-0.1 (rose 1.1)

- 1964-5: -1.7/-0.2 (rose 1.5)

- 1971-2: -1.5/-1.4 (rose 0.1)

- 1984-5: -1.6/+1.6 (rose 3.2)

- 1996-7: -1.2/+0.6 (rose 1.8)

- 2008-9: -1.4/+0.6 (rose 2.0)

- 2010-1: -1.8/+1.3 (rose 3.1)

- 2012-3: -1.0/+0.6 (rose 1.6)

- 2013-4: -0.9/+1.0 (rose 1.9)

- 2021-2: -2.6/+1.0 (rose 3.6)

So, average PNA rise Dec to Jan for these was a whopping 1.9!

 Today’s GEFS is progging ~-1.7 PNA for Dec as a whole. That would be ~5th strongest -PNA since 1950. But what were similarly strong -PNA Dec followed by in Jan since 1984-5 during -ENSO?

1984-5: from -1.6 to +1.6

2008-9: from -1.4 to +0.6

2010-1: from -1.8 to +1.3

2021-2: from -2.6 to +1.0

 All 4 of these Januaries were cold in the E US.

The radiational cooling in much of the SE has been quite impressive the last 4 hours!

 This afternoon’s walk was another pleasant one due to still pretty dry air (dewpoints mid 30s), blue skies, and light winds though it was ~20 warmer (60 vs 40). So, though it was pleasant, it felt better and more invigorating yesterday.

 Natural gas is down still another 3% today making it a total of a whopping 29% just since the high of Dec 4th!

30 minutes ago, wncsnow said:

I don't even have an account on there. 

7 minutes ago, BooneWX said:

You don’t have to. I peak over there to cross check the vibes and today is a hilarious war of words. That’s why I stick here. Everything is measured and while they have some great posters, it’s full of too many folks speaking in absolutes and getting obnoxious when the ball doesn’t roll their way. 
 

I go here to converse, read anything from @Carvers Gapto learn, and head there for my entertainment.

 The two forums are very intertwined between many (probably a majority) of its members also being members and former posters here as well as some currently posting at both (in some cases with different names). I’m sure many read both boards daily.

1 hour ago, BooneWX said:

It is what it is at this point. We won’t be the only ones suffering. Best advice I’ve got is for everyone to take a deep breath at the keyboard, go outside, smell some Christmas trees, golf, fish, get some vitamin d. It’s been a cold 3 weeks and a break won’t be bad. I hope it’s not extended but what can any of us do about it? Jammin January and Fab Feb are just around the corner. 

 For me it wouldn’t be “suffering”. It isn’t anything like, say, bad health/getting sick. “Suffering” is too harsh a word from my standpoint even though it’s not at all what I prefer as I want it colder than normal at any point in the year. The good thing is that it’s my favorite season of the year and warmer than normal in winter is still much colder than, say, below normal in summer. In addition, this warmer period will be following one of the coldest 3 week periods from Thanksgiving through the first 17 or so days of December I’ve ever experienced and easily the coldest since 2010.

 Even if it’s going to be mild for awhile, forecast discussions would still be interesting in the most volatile season of all, winter.