2024-2025 La Nina

[Allsnow]

 

[LakePaste25]

 

[donsutherland1]

14 minutes ago, LakePaste25 said:

 

A point worth repeating from last year, is that whether one is dealing with the MJO, teleconnections, etc., the coefficients of determination are low. Each variable has an impact on the pattern, but their explanatory power is sufficiently low that they can be overwhelmed by other variables.

[snowman19]

Euro's last monthly forecast did a pretty good job with the drop. IF it maintains its forecast accuracy, it hascthe Niña peaking mid-January. Euro monthly updates in around 10 days or so, so maybe it changes. I do think the westerlies the Eps has sneaking in before restarting trades will at least stall further cooling and may, I  said may (lol), interrupt the cooling process despite resumption of the trades. That would coincidence with the Euro's monthly forecast it seems.
Obviously, this is 1 possible scenario. We'll see.

There is going to be a brief, transient weakening of the trades and EWBs at the beginning of January, then they come right back in region 3.4. Also, region 1+2 is going to be much warmer than 3.4….very consistent with a classic CP/Modoki La Niña event

[GaWx]

PNA update:

1. The PNA after applying a rough 1.8 tabular conversion factor is roughly +1.8 MTD. It will be dropping for the rest of Dec as has been well predicted by GEFS means since the Dec 14th run. But I maintain that won’t be enough to prevent 2024 from having a decent shot at the record high Dec +PNA for non-El Nino, which is currently 2020’s +1.58. My current projection is for ~+1.45 to +1.70. So, it will probably be pretty close. The 2nd highest for non-Nino is 1960’s +1.46. So, I still think there’s a very good chance that 2024 will exceed the current 2nd highest and end up either highest or 2nd highest for non-Nino Dec PNA. (Records go back to 1950.)

 The reason I’ve been posting a lot about the strong Dec +PNA projection is that there’s a significant tendency for a strong non-Nino Dec PNA to carryover to Jan. As posted previously, the average Jan PNA for the non-Nino winters with the strongest 5 Dec PNAs on record has averaged +0.9 with 3 of the 5 Jans strong (within top 9 for non-Nino Jan): +1.51 (2001), +1.41 (1981), and +0.97 (1986). The other two were either weak +PNA (2006’s +0.43) or neutral (2021’s +0.19).

2. Even more significantly when looking ahead to Jan, especially with a strong -AO and moderate -NAO being predicted as well as a favorable for cold MJO, is to note that today’s 0Z GEFS based PNA prog for the 1st week of Jan has risen notably (see images below) and easily has the highest of the last 6 runs going into Jan as the 0Z GEFS maps showed a significant shift toward recent EPS runs:

 Here’s yesterday’s to compare to:

Tabular monthly PNA since 1950:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

[snowman19]

14 minutes ago, GaWx said:

PNA update:

1. The PNA after applying a rough 1.8 tabular conversion factor is roughly +1.8 MTD. It will be dropping for the rest of Dec as has been well predicted by GEFS means since the Dec 14th run. But I maintain that won’t be enough to prevent 2024 from having a decent shot at the record high Dec +PNA for non-El Nino, which is currently 2020’s +1.58. My current projection is for ~+1.45 to +1.70. So, it will probably be pretty close. The 2nd highest for non-Nino is 1960’s +1.46. So, I still think there’s a very good chance that 2024 will exceed the current 2nd highest and end up either highest or 2nd highest for non-Nino Dec PNA. (Records go back to 1950.)

 The reason I’ve been posting a lot about the strong Dec +PNA projection is that there’s a significant tendency for a strong non-Nino Dec PNA to carryover to Jan. As posted previously, the average Jan PNA for the non-Nino winters with the strongest 5 Dec PNAs on record has averaged +0.9 with 3 of the 5 Jans strong (within top 9 for non-Nino Jan): +1.51 (2001), +1.41 (1981), and +0.97 (1986). The other two were either weak +PNA (2006’s +0.43) or neutral (2021’s +0.19).

2. Even more significantly when looking ahead to Jan, especially with a strong -AO and moderate -NAO being predicted, is to note that today’s 0Z GEFS based PNA prog for the 1st week of Jan has risen notably (see images below) and easily has the highest of the last 6 runs going into Jan as the 0Z GEFS maps showed a significant shift toward recent EPS runs:

 Here’s yesterday’s to compare to:

Tabular monthly PNA since 1950:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

While the first couple of weeks of January may well average a positive PNA, I very seriously doubt it continues much past mid-month. I think we see a very different PNA regime in place come late January….

[mitchnick]

1 hour ago, snowman19 said:

There is going to be a brief, transient weakening of the trades and EWBs at the beginning of January, then they come right back in region 3.4. Also, region 1+2 is going to be much warmer than 3.4….very consistent with a classic CP/Modoki La Niña event

 

 

 

 

 

 

 

 

Agree on the return of trades after westerlies, but not so sure I'm sold on the certainty of that poster. If I  recall, Patel was predicting a few months ago with a lot of confidence how the Niña was coming and it was delayed as we now know. Not a lot of late peaking Niñas and latest forecasts from the  Euro and Cfs say it starts to fade in January, so whether Niña intensifies remains a question to me. Of course, Patel didn't say if the Niña would begin cooling again after trades return, so I'm not sure what value it is as to a forecast.

[LibertyBell]

14 hours ago, 40/70 Benchmark said:

I think its a great analog.

This might be controversial, but I'd rather have a La Nina than an El Nino.  El Nino winters torch early and seem to enhance the effects of global warming.  Thanks to La Nina we at least got a cold and somewhat snowy holiday period.  I'll take this over a torch December and praying for a fluke January/February blizzard which is what you need to get to normal snowfall in an el nino. This is MUCH better.

[LibertyBell]

1 hour ago, snowman19 said:

While the first couple of weeks of January may well average a positive PNA, I very seriously doubt it continues much past mid-month. I think we see a very different PNA regime in place come late January….

Maybe by January 20, but at least we can have a wintry period when the days are shortest and when we have our peak climo coldest weather. 

[LibertyBell]

6 hours ago, roardog said:

If I was betting, I would certainly bet against the Nino look sticking around the entire winter. However, that being said, it’s looking like we are essentially going to have this Nino like pattern for at least half of this met winter. For the people who like cold and snow chances in the east, you can’t ask for more than that with what everyone expected going into this winter. 

Not only that you are actually getting winter during peak climo winter rather than waiting for February, this is a lot better than the torch Decembers we get in el ninos

 

[LibertyBell]

14 hours ago, PhiEaglesfan712 said:

The closest analogs are 05-06, 08-09, and 21-22. Two of these (2006 and 2009) flipped to el nino the following year (with one, 09-10, being a strong el nino), while the third (2022) stayed a la nina. Oddly enough, the two that flipped to el nino produced strong la ninas in year 2, while the one that stayed a la nina flipped to a strong el nino in year 2. So I guess whatever ENSO state we have in 2025-26, we'll have the reverse in 2026-27 (and likely a strong event).

also need to factor in the lag effect of the solar max for upcoming winters

 

[LibertyBell]

5 hours ago, Allsnow said:

 

just need to correct that they got 2002 backwards

[GaWx]

12Z ensembles are still cold dominated in the E US day 9+:
- 12Z GEFS is colder than 6Z, which was overall slightly warmer (by 4 HDD) than the then coldest run to date 0Z and looks to be back at least about as cold as 0Z. Did it gain at least the full 4 HDD back? I’m guessing yes, which would mean at least tied for coldest run yet.

- 12Z EPS looks colder than 0Z, which was overall a bit warmer than yesterday’s 12Z, which had been the coldest run to date. The 0Z was 6 HDD warmer than yesterday’s 12Z. But today’s 12Z EPS may be back to at least as yesterday’s 12Z. If so, it is at least tied for coldest run yet.

 I’ve said this before and feel it deserves to be repeated for readers who don’t come here often and thus who may be confused. Based on some of the posts ITT, a reader not too familiar might not realize the cold potential in the E US for at least much of the 1st half of Jan. The potential is very real and is not baseless hype, which I actually hate. Model consensus has been insisting on this being likely. It will of course warm back up eventually. That’s obvious. But well before that we have the strong cold potential. It looks like the most intense cold would likely come in at least two waves meaning warming in between of course.

[LibertyBell]

14 minutes ago, GaWx said:

12Z ensembles are still cold dominated in the E US day 9+:
- 12Z GEFS is colder than 6Z, which was overall slightly warmer (by 4 HDD) than the then coldest run to date 0Z and looks to be back at least about as cold as 0Z. Did it gain at least the full 4 HDD back? I’m guessing yes, which would mean at least tied for coldest run yet.

- 12Z EPS looks colder than 0Z, which was overall a bit warmer than yesterday’s 12Z, which had been the coldest run to date. The 0Z was 6 HDD warmer than yesterday’s 12Z. But today’s 12Z EPS may be back to at least as yesterday’s 12Z. If so, it is at least tied for coldest run yet.

 I’ve said this before and feel it deserves to be repeated for readers who don’t come here often and thus who may be confused. Based on some of the posts ITT, a reader not too familiar might not realize the cold potential in the E US for at least much of the 1st half of Jan. The potential is very real and is not baseless hype, which I actually hate. Model consensus has been insisting on this being likely. It will of course warm back up eventually. That’s obvious. But well before that we have the strong cold potential. It looks like the most intense cold would likely come in at least two waves meaning warming in between of course.

It would be nice to place some benchmarks for the type of cold we might see.  I notice you often use NYC and ATL for your benchmarks.  I'm not familiar with ATL climo but as far as NYC is concerned, at peak cold, I think single digit temperatures are a high probability.  Not 0 or below because that's very rare anyway but 5 or so might be a reasonable possibility.

 

[Stormchaserchuck1]

17 hours ago, PhiEaglesfan712 said:

The closest analogs are 05-06, 08-09, and 21-22. Two of these (2006 and 2009) flipped to el nino the following year (with one, 09-10, being a strong el nino), while the third (2022) stayed a la nina. Oddly enough, the two that flipped to el nino produced strong la ninas in year 2, while the one that stayed a la nina flipped to a strong el nino in year 2. So I guess whatever ENSO state we have in 2025-26, we'll have the reverse in 2026-27 (and likely a strong event).

That's kind of a small sample size though. We know that in +3-6 years we have twice as likely chance of El Nino vs La Nina, but the odds are a bit more even, if not slightly favoring cold ENSO, next year. 

[GaWx]

 The latest model consensus covering much of the 1st half of Jan suggests a good chance for  a +PNA (trended recently from neutral or -PNA), -AO, and -NAO. (The 2nd half of the month, which only the extended ensembles show, is still too far out for reliability.)

 During non-El Nino DJF back to 1950, these are the 15 non-Nino months with a +PNA (+0.25+), AO (-0.5-), and -NAO (-0.25-) along with E US temps:

-2/2013 (weak +PNA/-NAO; +EPO): cool SE/MidATL, NN NE

-1/2011: cold

-12/2005: cold

-1/2004 (weak +PNA/-NAO but -EPO): cold

-12/2001 (+EPO): mild

-12/2000: cold

-12/1995: cold

-12/1989: cold

-1/1985: cold

-2/1968: cold

-2/1963: cold

-1/1963: cool

-1/1960: mild

-1/1955 (+EPO): cool

-12/1952 (+EPO): cool SE/mild NE

 

So, 11 of these 15 were cold or cool most everywhere.

The other 4:

-2/2013: +PNA and -NAO weak and +EPO 

-12/2001: +EPO

-1/1960: can’t explain

-12/1952: +EPO

 

  So, if we end up with the full Jan averaging +PNA/-AO/-NAO and considering the favorable MJO for at least the 1st half, the odds would be high that the only index standing in the way of a cool to cold E US Jan would be a +EPO. Current consensus has it mainly negative to neutral much of first half of Jan.

[PhiEaglesfan712]

I actually think the below normal temperatures for the 1/4 to 1/17 period will be contained to south of DCA. North of DCA, I think we'll see near normal temperatures for that period, and well above average temperatures for the last 2 weeks of January.

[roardog]

43 minutes ago, PhiEaglesfan712 said:

I actually think the below normal temperatures for the 1/4 to 1/17 period will be contained to south of DCA. North of DCA, I think we'll see near normal temperatures for that period, and well above average temperatures for the last 2 weeks of January.

Nothing about the upcoming pattern would indicate that areas north of DC wouldn’t be below average. I mean the great ensemble agreement could be wrong but they show a flow direct from the North Pole into the east. The lowest heights in the hemisphere are in eastern Canada and the eastern US. 

[Snowstorms]

4 hours ago, LibertyBell said:

This might be controversial, but I'd rather have a La Nina than an El Nino.  El Nino winters torch early and seem to enhance the effects of global warming.  Thanks to La Nina we at least got a cold and somewhat snowy holiday period.  I'll take this over a torch December and praying for a fluke January/February blizzard which is what you need to get to normal snowfall in an el nino. This is MUCH better.

I guess it depends where you're geographically located. A strong El Nino is an almost guaranteed torch especially now with climate change and we can see that radical shift after the 70's. 82-83, 91-92, 97-98, 15-16, and 23-24 all blowtorches.

El Nino's are great in offering big storm potentials. However, most moderate-strong Nina's that were preceded by El Nino's can offer a lot of storm potentials and we saw this with 2007-08, 2010-11, 2016-2018. Most weak Nino's are great at keeping a weak Aleutian low present allowing for good cross polar and blocking patterns to emerge.  

Similarly, La Nina is great if its dominating the pattern which allows for a poleward Aleutian ridge which can either morph into a -EPO pattern or allow for cross polar flow with a -AO/NAO. It may keep the centre of cold near the Plains and Midwest, but it's good for allowing strong gradient storms to develop or coastal storms when the trough displaces east. This also helps keep a longer lasting snow cover. 

I prefer mod-strong La Nina's and weak Nino's. Weak Nina's (ONI <= -0.9) or strong Nino's can go either way. Mod Nino's are okay, if we have good blocking. 

Merry Christmas 

 

[40/70 Benchmark]

4 hours ago, roardog said:

Nothing about the upcoming pattern would indicate that areas north of DC wouldn’t be below average. I mean the great ensemble agreement could be wrong but they show a flow direct from the North Pole into the east. The lowest heights in the hemisphere are in eastern Canada and the eastern US. 

He's been calling for a January torch since last fall, so that's probably where it stems from.

[George001]

8 hours ago, LibertyBell said:

This might be controversial, but I'd rather have a La Nina than an El Nino.  El Nino winters torch early and seem to enhance the effects of global warming.  Thanks to La Nina we at least got a cold and somewhat snowy holiday period.  I'll take this over a torch December and praying for a fluke January/February blizzard which is what you need to get to normal snowfall in an el nino. This is MUCH better.

Interestingly, weak La Ninas are snowier than ENSO neutral for my area. So I’m glad to see that La Niña development has progressed during December. 

[George001]

12 minutes ago, 40/70 Benchmark said:

He's been calling for a January torch since last fall, so that's probably where it stems from.

I was calling for a January torch in my winter forecast, thats one of the reasons why I put said forecast on bust watch last night.

[40/70 Benchmark]

31 minutes ago, George001 said:

I was calling for a January torch in my winter forecast, thats one of the reasons why I put said forecast on bust watch last night.

Went +3 to +5 in December, which is off....PNA killed me. I expected that in January, not December. 

[Maxim]

Still wouldn’t rule out a warm month for a good chunk of the CONUS. The Euro AIFS in particular is not at all buying into the cold that the GFS seems to be exaggerating in recent runs.

[MJO812]

2 minutes ago, Maxim said:

Still wouldn’t rule out a warm month for a good chunk of the CONUS. The Euro AIFS in particular is not at all buying into the cold that the GFS seems to be exaggerating in recent runs.

Euro AI hasn't been accurate at all

 

[snowman19]

7 minutes ago, Maxim said:

Still wouldn’t rule out a warm month for a good chunk of the CONUS. The Euro AIFS in particular is not at all buying into the cold that the GFS seems to be exaggerating in recent runs.

IMO it doesn’t get warm in the east until after mid-January. Come late month, I think it’s canonical La Niña time…..-PNA/RNA and the SE ridge pops

[roardog]

2 hours ago, snowman19 said:

IMO it doesn’t get warm in the east until after mid-January. Come late month, I think it’s canonical La Niña time…..-PNA/RNA and the SE ridge pops

I’m kind of at the point of I’ll believe when I see it. Even at the end of today’s ensembles, there’s no sign of that type of pattern developing. The warmer look on the AI is due to lower heights in Alaska and Canada allowing a mild westerly flow across the country not due to any kind of SE ridge. 

[LakePaste25]

47 minutes ago, roardog said:

I’m kind of at the point of I’ll believe when I see it. Even at the end of today’s ensembles, there’s no sign of that type of pattern developing. The warmer look on the AI is due to lower heights in Alaska and Canada allowing a mild westerly flow across the country not due to any kind of SE ridge. 

It is indeed too early for this to start showing up on the medium range ensembles. The MJO progression and La Niña strengthening all allude to the traditional Nina February climo taking hold between after mid-month and early February. But as discussed yesterday, it’s not a sole predictor. Wildcards are there, such as the SPV. For now, I would simply lean towards this progression. 

[snowman19]

This hasn’t been just a 1 or 2 week push towards La Niña, it’s been a strong, sustained oceanic and atmospheric push since November and it looks to continue into January. There is going to be a NPAC response to what has and continues to be going on in the tropical PAC

[GaWx]

39 minutes ago, snowman19 said:

This hasn’t been just a 1 or 2 week push towards La Niña, it’s been a strong, sustained oceanic and atmospheric push since November and it looks to continue into January. There is going to be a NPAC response to what has and continues to be going on in the tropical PAC
 

 Despite the recent at or near record rapid strengthening of La Niña from Nov to Dec, Jan is likely going to be another BN temps month in much of the E US.  If so and with 2 of the 3 winter months BN, this winter would highly likely not be the AN E US winter (+2+ F) many including both of us expected. In that case Feb would have to be an absolute blowtorch just for the slight chance for DJF to average +2+.