2024-2025 La Nina

[40/70 Benchmark]

2 hours ago, bluewave said:

The EPS tends to be too weak with its MJO amplitude near the end of the effective 15 day forecast period when going into phase 4-6 like it’s showing in early December. So if we look at the VP anomalies charts they are all showing this current MJO in the IO progressing to the Maritime Continent in December but the GEFS is stronger. If there isn’t to be some type of mismatch like we saw in 2020, I expect the models to correct stronger going into 4-6 in December over the next few weeks. Then the models will be playing catch up with the milder pattern over the next few weeks and especially during the first week of December due to the lag between the MJO convection and the eventual 500mb response. Also note the record SSTs near the Maritime Continent with the -IOD which could stall the MJO in 4-6 well into December beyond what the current weekly forecasts are showing.

 

GEFS stronger with MJO 4-6 VP anomalies in early December

 

 

This is what I expect...that mid December, phase 6 period to get pushed back and muted. Phase 6 is actually decent, -WPO ish in December, so it would probbaly have to stall in 5...at least for NE. Probably not for your area and the mid atl.

[GaWx]

3 hours ago, bluewave said:

The EPS tends to be too weak with its MJO amplitude near the end of the effective 15 day forecast period when going into phase 4-6 like it’s showing in early December. So if we look at the VP anomalies charts they are all showing this current MJO in the IO progressing to the Maritime Continent in December but the GEFS is stronger. If there isn’t to be some type of mismatch like we saw in 2020, I expect the models to correct stronger going into 4-6 in December over the next few weeks. Then the models will be playing catch up with the milder pattern over the next few weeks and especially during the first week of December due to the lag between the MJO convection and the eventual 500mb response. Also note the record SSTs near the Maritime Continent with the -IOD which could stall the MJO in 4-6 well into December beyond what the current weekly forecasts are showing.

 

GEFS stronger with MJO 4-6 VP anomalies in early December

 

 

 I agree with the bolded. Thus due to Euro ensemble often being too weak going into the right side of the diagram, I’ve found the GEFS to be about the most accurate of the models going into the right side. Currently the EPS is much weaker as you stated.

[GaWx]

48 minutes ago, mitchnick said:

0z run of the Cfs2 weeklies shows a cooler 2-3 weeks than previous runs, but then starts to warm toward the end of the month of December. The Cfs2 is definitely on board with a strong pass thru the warm phases and has been for days, so I  assume it represents your thinking.

https://www.tropicaltidbits.com/analysis/models/?model=cfs-avg&region=us&pkg=T2maMean&runtime=2024111500&fh=504

But the monthly forecast shows a normal to BN temps in the MA & NE for January. My guess is it holds a fairly strong wave into the cooler phases to support the cooler January. 

 I found in my multidecadal analyses for winter that stronger amplitude of MJO hasn’t correlated to colder in the E US in the means. I actually found the opposite: weaker tended to be colder (in the means). After doing my own analyses, I then found this (for all seasons), which agrees with my findings that cold in the E US correlates best with weak MJO rather than strong:

[40/70 Benchmark]

3 minutes ago, GaWx said:

 I found in my multidecadal analyses that stronger amplitude of MJO hasn’t correlated to colder in the E US in the means. I actually found the opposite: weaker tended to be colder (in the means). After doing my own analyses, I then found this, which agrees with my findings that cold in the E US correlates best with weak MJO rather than strong:

My guess is that is due to the warmer phases outperforing the colder phases as a result of CC, so overall less amplitutude would correlate to cold in the mean. However, I will take high amplitude in the colder phases.

[GaWx]

57 minutes ago, 40/70 Benchmark said:

My guess is that is due to the warmer phases outperforing the colder phases as a result of CC, so overall less amplitutude would correlate to cold in the mean. However, I will take high amplitude in the colder phases.

1. Colder phases outside the circle in winter averaged colder than inside the circle for warm phases in my own studies, especially in or near midwinter. But I found amplitude of 0.5 to 1.5 left side to be colder in the means than 1.5+ left side.
 

2. The following is from that same outside study (that I found after doing my own analyses) but just for winter: just outside circle and inside the circle MJO (amp of <1.5) averaged colder than stronger (>1.5):

[michsnowfreak]

1 hour ago, mitchnick said:

0z run of the Cfs2 weeklies shows a cooler 2-3 weeks than previous runs, but then starts to warm toward the end of the month of December. The Cfs2 is definitely on board with a strong pass thru the warm phases and has been for days, so I  assume it represents your thinking.

https://www.tropicaltidbits.com/analysis/models/?model=cfs-avg&region=us&pkg=T2maMean&runtime=2024111500&fh=504

But the monthly forecast shows a normal to BN temps in the MA & NE for January. My guess is it holds a fairly strong wave into the cooler phases to support the cooler January. 

The CFS (and several other models) has been steadfast in having well below average temps in already frigid Canada in the coldest month of the year (Jan), and the same for Feb. Never any guarantees, but I like that look and the potential it holds.

[mitchnick]

59 minutes ago, bluewave said:

If you take the totality of the forcing driving the Rossby wave patterns we have experienced a slowing and amplification of the convection near the Maritime Continent as the WPAC warm pool has greatly expanded over the years. The models begin to hint at movement from the IO to Maritime Continent in the longer ranges but their amplitudes of the forcing are usually too weak. So if you run back the those Euro weeklies VP anomaly charts and animate then you see the short term correction stronger where the amplitudes have been too weak. This is one of the reasons the Euro weeklies shift around so much after 10-15 days since they underestimate the convection near the Maritime Continent and other key forcing regions. Perhaps the weeklies could become reliable after 15 days if they incorporate AI into them to correct this bias. That may be when the model can make a significant improvement week 2 to 4. But not sure if they have the technology yet needed  to pull off that feat.

We should actually have a pretty good idea which camp is on the right track in a few days. When you compare the Euro/JMA to the GFS/CFS, the Gfs/CFS have the wave exiting the COD within a few days while the other 2 keep it buried in the COD.

[snowman19]

4 hours ago, bluewave said:

If you take the totality of the forcing driving the Rossby wave patterns we have experienced a slowing and amplification of the convection near the Maritime Continent as the WPAC warm pool has greatly expanded over the years. The models begin to hint at movement from the IO to Maritime Continent in the longer ranges but their amplitudes of the forcing are usually too weak. So if you run back the those Euro weeklies VP anomaly charts and animate then you see the short term correction stronger where the amplitudes have been too weak. This is one of the reasons the Euro weeklies shift around so much after 10-15 days since they underestimate the convection near the Maritime Continent and other key forcing regions. Perhaps the weeklies could become reliable after 15 days if they incorporate AI into them to correct this bias. That may be when the model can make a significant improvement week 2 to 4. But not sure if they have the technology yet needed  to pull off that feat.

The CPC has just spoken: 

[Terpeast]

57 minutes ago, snowman19 said:

The CPC has just spoken: 

That’s to be expected as the mjo circles through the warm phases. It’s what happens after that I’m interested in.

[roardog]

39 minutes ago, Terpeast said:

That’s to be expected as the mjo circles through the warm phases. It’s what happens after that I’m interested in.

If we can keep a nice stout Aleutian ridge to keep the Arctic air coming into North America and the MJO actually does make it into the cold phases, you guys might have a nice window later in December with cold air already close by. 

[GaWx]

Euro Weeklies mean over last couple of days has reverted back to a strong SPV throughout Dec: today’s is as strong as any run yet

[brooklynwx99]

1 hour ago, GaWx said:

Euro Weeklies mean over last couple of days has reverted back to a strong SPV throughout Dec: today’s is as strong as any run yet

i will never understand why they decided to run the weeklies every day 

[mitchnick]

2 hours ago, brooklynwx99 said:

i will never understand why they decided to run the weeklies every day 

That's because you don't speak French.

[snowman19]

8 hours ago, Terpeast said:

That’s to be expected as the mjo circles through the warm phases. It’s what happens after that I’m interested in.

Yes I agree. December is starting to look like a very warm month. MJO forcing in warm phases (-IOD, -PDO, -ENSO = +EPO/-PNA, neutral WPO) and the SPV is about to go on steroids (+NAO/+AO). The entire subseasonal picture looks warm to very warm, PAC side, Atlantic side, arctic side. Question becomes does it change come January?

[GaWx]

1 hour ago, snowman19 said:

Yes I agree. December is starting to look like a very warm month. MJO forcing in warm phases (-IOD, -PDO, -ENSO = +EPO/-PNA, neutral WPO) and the SPV is about to go on steroids (+NAO/+AO). The entire subseasonal picture looks warm to very warm, PAC side, Atlantic side, arctic side. Question becomes does it change come January?

1. If this leads to <3” of SN in Dec at NYC, look for Jan+ SN to likely be solidly BN per bluewave’s stats.

2. I just looked at the comparison of US HDDs for 11/23-27 on the 0Z 11/14 EPS and the same on both the 12Z 11/15 and 0Z 11/16 runs. The warming was strong as it went from an average of 0.5 AN HDDs to 3+ BN HDDs! Whereas the 0Z 11/14 run had 4 days with AN HDDs, the last 2 runs had no days like that! Is this a sign of what’s to come this winter on the EPS? Are the various ensembles going to once again be cold biased much of the time like has been the case for much of the last 7-8 years?

[mitchnick]

In case you're interested, here's a link to all the MJO forecasts on 1 page that make them a whole lot easier to compare. They are the same forecasts as the CPC site. Note that like the CPC site, however, starting dates of the forecasts are not always the same.

https://www.stormsurf.com/page2/links/mjo_phase.html

[mitchnick]

Yesterday's weeklies have increased the number of weeks to 5 out of 6 with a trough over or near Japan, though an argument could be made that it's all 6 imho.

https://charts.ecmwf.int/products/extended-anomaly-z500?base_time=202411150000&projection=opencharts_eastern_asia&valid_time=202411250000

[mitchnick]

1 hour ago, bluewave said:

The interesting thing about a trough near Japan in December is that it can be a precursor to some type of El Niño in 25-26. We saw this pattern in December 2022, 2014, and 2001 with El Niños the following winters. But it would be a first to go back into El Niño so soon after last winter so I am not ready yet to buy that idea that some of the long range models are currently showing until we see how things go next spring and summer. 
 

Maybe, who knows. All I  know is that it correlates well with a trough in the east and will likely help waters to cool which, imho, will rise the PDO, and any rise will help.

[snowman19]

19 minutes ago, mitchnick said:

Maybe, who knows. All I  know is that it correlates well with a trough in the east and will likely help waters to cool which, imho, will rise the PDO, and any rise will help.

The tropical forcing progression in December is going to be completely unsupportive of an east coast trough. Does it change in January? Going to have to wait and see

[mitchnick]

27 minutes ago, snowman19 said:

The tropical forcing progression in December is going to be completely unsupportive of an east coast trough. Does it change in January? Going to have to wait and see

I'm not seeing a wall-to-wall December furnace at this point as I  thought a few weeks ago. I think there will be at least 1 week, maybe 2 in the NE, with a shot(s) of wintry weather. But January will be the do or die month for most in the east, at least that's the way it looks now (subject to change, of course.)

[GaWx]

2 hours ago, bluewave said:

The interesting thing about a trough near Japan in December is that it can be a precursor to some type of El Niño in 25-26. We saw this pattern in December 2022, 2014, and 2001 with El Niños the following winters. But it would be a first to go back into El Niño so soon after last winter so I am not ready yet to buy that idea that some of the long range models are currently showing until we see how things go next spring and summer. 
 

Regarding the bolded:

-2004,5,6 was Nino, Niña, Nino

-1963,4,5 was the same

-1923,4,5 “ “

-1902,3,4 “ “

-1885,6,7 “ “

-Since 1851 there were 19 cases of Nino to Niña. Out of these 19, 5 ended up Nino to Niña to Nino.

-So, they’re not as rare as one might think.

-Last 3 runs of CANSIPS have been showing Modoki Nino next summer fwiw.

[PhiEaglesfan712]

2 hours ago, mitchnick said:

Maybe, who knows. All I  know is that it correlates well with a trough in the east and will likely help waters to cool which, imho, will rise the PDO, and any rise will help.

Yeah, I think 2025 will be more of a rise in the PDO, rather than an el nino formation, kind of like 2013. I think the ENSO in 2025-26 will be near neutral like 2013-14 or 2014-15. I think the el nino is more likely to happen in either 2026-27 or even 2027-28. We're probably getting ready to transition from a secular -PDO period to a secular +PDO period (like in the late 70s).

[qg_omega]

Record warmth looks likely to start December 

[George001]

42 minutes ago, qg_omega said:

Record warmth looks likely to start December 

Correct. Things do not look good at all, all the fall indicators looked bad. It has been very very warm so far this November, and it has also been very dry. I was holding out a glimmer of hope that the long range guidance had a clue with the shift to a -EPO pattern, but that is already looking transient. 3 weeks of warmth, a week of cold and then December starts and right back to warm.  If that 3 weeks warm 1 week cold rinse and repeat pattern continues into the winter, there is no realistic hope for winter prospects in the East. You need at least a 2 week warm/2 week cold, otherwise you are relying on getting lucky in a bad pattern which is not sustainable. I’m not pulling the plug yet, too early but if I don’t see any signs of sustained cold in the next 2 weeks in the medium range I am out on this winter.

[George001]

I was more optimistic a month ago, but things change. It’s important to be objective and make adjustments as we get new information. There are 2 possible paths, the 08-09/10-11/13-14 one or the 16-17/01-02/21-22 one. Unfortunately, we appear to be trending towards the second camp. 

[PhiEaglesfan712]

I disagree. I see the first third of December being cool, and I think there's a chance of a snow event on Dec 4 or 5. The second third looks warm, and I think it will be back to cool again the final third. (I go to the Eagles game on Dec. 29. I don't think this one will be a torch like the first week of January 2023.)

January is likely to be very warm. As I've said all along, the winter comes down to February. I think that final month of winter looks the most promising, but it's way too early to tell.

[michsnowfreak]

33 minutes ago, George001 said:

Correct. Things do not look good at all, all the fall indicators looked bad. It has been very very warm so far this November, and it has also been very dry. I was holding out a glimmer of hope that the long range guidance had a clue with the shift to a -EPO pattern, but that is already looking transient. 3 weeks of warmth, a week of cold and then December starts and right back to warm.  If that 3 weeks warm 1 week cold rinse and repeat pattern continues into the winter, there is no realistic hope for winter prospects in the East. You need at least a 2 week warm/2 week cold, otherwise you are relying on getting lucky in a bad pattern which is not sustainable. I’m not pulling the plug yet, too early but if I don’t see any signs of sustained cold in the next 2 weeks in the medium range I am out on this winter.

You seem to be quite knowledgeable, but honestly, it seems crazy to me to pull the plug on an entire winter on the east coast if you don't see sustained cold in November. It just doesn't make sense. You talk about 16-17 frequently...well there was plenty of cold from Thanksgiving to Christmas. How did the rest of that winter work out?

And also I do not see any signs of record warmth starting December.

[michsnowfreak]

7 minutes ago, PhiEaglesfan712 said:

I disagree. I see the first third of December being cool, and I think there's a chance of a snow event on Dec 4 or 5. The second third looks warm, and I think it will be back to cool again the final third. (I go to the Eagles game on Dec. 29. I don't think this one will be a torch like the first week of January 2023.)

January is likely to be very warm. As I've said all along, the winter comes down to February. I think that final month of winter looks the most promising, but it's way too early to tell.

I disagree on January. I'm really liking January here, and while it will probably be somewhat milder than normal on the east coast it's probably your best winter month this season. I think @40/70 Benchmarkalso thinks Jan will be be your best month. A few months ago I thought Dec might be great and Jan would suck (going by some previous nina years) but I've completely flipped recently. Dec looks to have it's chances but should be the least favorable of the 3 winter months. Cfs and some other models have been steadfast on western Canada just loaded with cold by January. 

[bluewave]

2 hours ago, GaWx said:

Regarding the bolded:

-2004,5,6 was Nino, Niña, Nino

-1963,4,5 was the same

-1923,4,5 “ “

-1902,3,4 “ “

-1885,6,7 “ “

-Since 1851 there were 19 cases of Nino to Niña. Out of these 19, 5 ended up Nino to Niña to Nino.

-So, they’re not as rare as one might think.

-Last 3 runs of CANSIPS have been showing Modoki Nino next summer fwiw.

You have to examine the magnitudes to understand the rarity. There were no El Niños this soon after a +2.0 or greater ONI event like we had last winter. Think 15-16, 97-98, 82-83, 72-73 and 65-66. None of those events had a follow up El Niño only 2 years later. That’s why it would be extremely rare for us to go back to El Niño so soon unless the unprecedented global temperature rise last 17 months is signaling some type of new climate shift. But it’s way to early to know the state of the ENSO next winter since in the past another La Niña has been favored.

[qg_omega]

This sums up last winter