2024-2025 La Nina

[PhiEaglesfan712]

46 minutes ago, bluewave said:

Subsurface continues to warm and Nino 1+2 is still holding at +0.8 for the week. We have a real shot at not reaching a -0.5 trimonthly following the +2.0 peak last year. This would be a first since 1950 for the following year from such a strong El Niño. Global SSTs are almost as warm as last year so this is really inhibiting La Niña development. It will be interesting if this is signaling an era with more frequent El Niños than we have seen since the 1980s when La Nina’s increased over that period. 
 

23-24…..+2.0 peak…lowest so far -0.2

15-16…..+2.6 peak with following year low at -0.7

97-98…..+2.4……-1.6

82-83…..+2.2……-1.0

72-73……+2.1…..-2.0

65-66……+2.0….-0.5

 

https://www.cpc.ncep.noaa.gov/data/indices/

https://www.cpc.ncep.noaa.gov/data/indices/wksst9120.for

20NOV2024     22.7 0.8     25.2 0.1     26.7-0.1     28.8 0.1

I don't consider 2023-24 a super el nino. The RONI never reached 1.5 and the MEI only had one bimonthly at 1 (basically a weak el nino like 2006-07). 1991-92 has a better case for a super el nino, as it reached +2 on both the RONI and MEI. If included, 1992 would be a precedent year (since it never went to la nina, and in fact stayed an el nino on the MEI until 1995).

[mitchnick]

9 minutes ago, bluewave said:

The Pacific Jet is still Niña-like in strength. Notice the trough correcting closer to the Aleutians for the start of December. If the models continue to underestimate it, then the ridge axis will gradually start drifting east in later runs. So it will be a battle between the jet extensions enhancing the ridge and trying to weaken it. Modeling by next week will probably give us a more definitive answer as to where that ridge axis ends up in mid to late December.

New run stronger jet carving out trough near the Aleutians with ridge axis into the West 

 

 

Old run jet was weaker with ridge axis further west

 

If you go to the N Hemisphere link below and put last night's EPS run in motion, backwards and forward, you can see that the cause of the weakness in the ridge is from the remnants of the prior trough off the Aleutians that was dragged back into the next trough replacing that prior trough. The ridge was solid before the weakness you mentioned and quickly corrects back to a strong state. So although it may happen as you muse sometime in the future, I don't think last night's run is an example of that. Otoh, if you think that interaction does represent a Niña strength Pacific Jet, it's effects were so brief and overpowered by the stability of the pattern it argues against the Pacific Jet being the source of a collapse in the pattern any time soon imho.

https://www.tropicaltidbits.com/analysis/models/?model=eps&region=nhem&pkg=z500a&runtime=2024112600&fh=132

[bluewave]

25 minutes ago, mitchnick said:

If you go to the N Hemisphere link below and put last night's EPS run in motion, backwards and forward, you can see that the cause of the weakness in the ridge is from the remnants of the prior trough off the Aleutians that was dragged back into the next trough replacing that prior trough. The ridge was solid before the weakness you mentioned and quickly corrects back to a strong state. So although it may happen as you muse sometime in the future, I don't think last night's run is an example of that. Otoh, if you think that interaction does represent a Niña strength Pacific Jet, it's effects were so brief and overpowered by the stability of the pattern it argues against the Pacific Jet being the source of a collapse in the pattern any time soon imho.

https://www.tropicaltidbits.com/analysis/models/?model=eps&region=nhem&pkg=z500a&runtime=2024112600&fh=132

Right now we are seeing a constructive interference pattern with the Pacific Jet extensions enhancing the ridge position. Though the position is further east than forecast due to the stronger Pacific Jet influence. My guess is that it will be a battle between those forces for December. If the constructive interference wins out ,then the ridge will stay out West for all of December and only slightly drifting into the Plains at times. But if the the Jet stream disturbances can push through due to the stronger Pacific Jet, then the ridge will shift East by mid to to late December and the whole pattern will relax. So a small difference between the forces can tip the scales one way or another. You can see the older run of the EPS underestimating the Pacific Jet.

 
New run stronger Pacific Jet  with lower heights near Alaska 

Old run EPS weaker jet

 

 

 

[PhiEaglesfan712]

There seems to be a shift with the recent strong el ninos. The 2015-16 and 2023-24 el ninos didn't drop below -0.5C. (This is the first time that two consecutive strong el ninos didn't drop below -0.5 since the 1957-58 and 1965-66 el ninos.) That differs from the 1972 to 2011 period, when all strong el ninos (+1.5) dropped below the -0.5C threshold, except 1991-92.

1957-58 -> no

1965-66 -> no

1972-73 -> yes (strong la nina 1973-74)

1982-83 -> yes

1986-88 -> yes (strong la nina 1988-89)

1991-92 -> no

1997-98 -> yes (strong la nina 1998-2000)

2010-11 -> yes (strong la nina 2010-11)

2015-16 -> no

2023-24 -> no

[bluewave]

44 minutes ago, PhiEaglesfan712 said:

I don't consider 2023-24 a super el nino. The RONI never reached 1.5 and the MEI only had one bimonthly at 1 (basically a weak el nino like 2006-07). 1991-92 has a better case for a super el nino, as it reached +2 on both the RONI and MEI. If included, 1992 would be a precedent year (since it never went to la nina, and in fact stayed an el nino on the MEI until 1995).

It was a borderline super event with one ONI reaching +2.0. A lower RONI doesn’t diminish the actual Nino 3.4 SSTs. So it’s not a metric used to evaluate the El Niño strength.

[snowman19]

12 minutes ago, bluewave said:

Right now we are seeing a constructive interference pattern with the Pacific Jet extensions enhancing the ridge position. Though the position is further east than forecast due to the stronger Pacific Jet influence. My guess is that it will be a battle between those forces for December. If the constructive interference wins out ,then the ridge will stay out West for all of December and only slightly drifting into the Plains at times. But if the the Jet stream disturbances can push through due to the stronger Pacific Jet, then the ridge will shift East by mid to to late December and the whole pattern will relax. So a small difference between the forces can tip the scales one way or another. You can see the older run of the EPS underestimating the Pacific Jet.

 
New run stronger Pacific Jet  with lower heights near Alaska 

Old run EPS weaker jet

 

 

 

EPS and to a certain extent the GEPS (though not nearly as bad) has been doing this in the long range for years now. The EPS is by far the worst at constantly trying to incorrectly weaken and retract the PAC jet and it’s an ongoing issue despite the upgrades

[PhiEaglesfan712]

1 minute ago, bluewave said:

It was a borderline super event with one ONI reaching +2.0. A lower RONI doesn’t diminish the actual Nino 3.4 SSTs. So it’s not a metric used to evaluate the El Niño strength.

But we do have a similar precedent for this with 1992 not going la nina (even if it was affected by Mt. Pinatubo, and the global temperatures are ~1C warmer now than in 1992).

1991-92 was a similar el nino strength as 2023-24 (maybe even stronger).

[mitchnick]

26 minutes ago, bluewave said:

Right now we are seeing a constructive interference pattern with the Pacific Jet extensions enhancing the ridge position. Though the position is further east than forecast due to the stronger Pacific Jet influence. My guess is that it will be a battle between those forces for December. If the constructive interference wins out ,then the ridge will stay out West for all of December and only slightly drifting into the Plains at times. But if the the Jet stream disturbances can push through due to the stronger Pacific Jet, then the ridge will shift East by mid to to late December and the whole pattern will relax. So a small difference between the forces can tip the scales one way or another. You can see the older run of the EPS underestimating the Pacific Jet.

 
New run stronger Pacific Jet  with lower heights near Alaska 

Old run EPS weaker jet

 

 

 

Isn't the strength of the features in close vs far out more just a function of the weakening of features the further out you go in the forecast? For example, taking the 300hr map from 0z 11/19 compared to last night's run, surface temps are wayyy colder . But that's not due to a different pattern, rather the closer in time you go with ensemble forecasting, the more clarity ---> strength many features will have (providing the same basic pattern holds thru the period, of course.)

[snowman19]

4 minutes ago, mitchnick said:

Isn't the strength of the features in close vs far out more just a function of the weakening of features the further out you go in the forecast? For example, taking the 300hr map from 0z 11/19 compared to last night's run, surface temps are wayyy colder . But that's not due to a different pattern, rather the closer in time you go with ensemble forecasting, the more clarity ---> strength many features will have (providing the same basic pattern holds thru the period, of course.)

I think the larger issue is the EPS’s handling of the PAC in the long range. For whatever reason it does a really bad job on the PAC side, has for years and it hasn’t gotten any better. Last year was a great example. Surprisingly, the GEFS has done way better and the EPS is always playing catchup. I’m not really sure what they did as far as the EURO upgrades but it hasn’t helped

[bluewave]

21 minutes ago, snowman19 said:

EPS and to a certain extent the GEPS (though not nearly as bad) has been doing this in the long range for years now. The EPS is by far the worst at constantly trying to incorrectly weaken and retract the PAC jet and it’s an ongoing issue despite the upgrades

While the early December pattern will be colder than normal, it really isn’t that cold by early December historical standards. The slightly lower heights near Alaska are allowing some Pacific air mass moderation. Plus the record fall warmth and low snow cover are having an influence. 

[PhiEaglesfan712]

For the record, I'd gladly take a 1992-93 type winter. That one was backloaded (of course, highlighted by the Blizzard in mid-March), with January being the very warm month.

In this 2024-25 climate, I highly doubt we get a blizzard of that magnitude in mid-March. It would probably fall down as mostly rain. That's probably the winter version of Hurricane Sandy.

[bluewave]

27 minutes ago, mitchnick said:

Isn't the strength of the features in close vs far out more just a function of the weakening of features the further out you go in the forecast? For example, taking the 300hr map from 0z 11/19 compared to last night's run, surface temps are wayyy colder . But that's not due to a different pattern, rather the closer in time you go with ensemble forecasting, the more clarity ---> strength many features will have (providing the same basic pattern holds thru the period, of course.)

I was discussing the strength of the Pacific Jet and the ridge axis ending up well to the east of the old EPS run. So the pattern is different from what the model was originally showing. More amplified ridge out West and deeper trough in East is why the East is forecast to be colder and the West warmer than the earlier runs. 

[GaWx]

53 minutes ago, bluewave said:

It was a borderline super event with one ONI reaching +2.0. A lower RONI doesn’t diminish the actual Nino 3.4 SSTs. So it’s not a metric used to evaluate the El Niño strength.

 Yes, 2023-4 was officially a borderline super event or a super “in name only”. But it was only a borderline moderate/strong El Niño at most for all practical purposes when taking the overall tropical waters’ warming into account. For a similar reason, we’re currently for all practical purposes in a weak La Niña even though officially it may end up cold neutral.

[PhiEaglesfan712]

9 minutes ago, GaWx said:

 Yes, 2023-4 was officially a borderline super event. But it was only a borderline moderate/strong El Niño at most for all practical purposes when taking the overall tropical waters’ warming into account. For a similar reason, we’re currently for all practical purposes in a weak La Niña even though officially it may end up cold neutral.

But 1992 gives us a precedent for strong/borderline super el nino event not going la nina though, correct?

[GaWx]

8 minutes ago, PhiEaglesfan712 said:

But 1992 gives us a precedent for strong/borderline super el nino event not going la nina though, correct?

For all practical purposes, I say yes. Actually, for all practical purposes, 1991-2 was a solid super-Nino with a +2.3 trimonthly peak per RONI along with 4 trimonthlies in a row of +2+. So, not just a borderline super.

[George001]

I wouldn’t say last years Nino resembled a moderate event. The temp and precip profile resembled the borderline super Nino composite. The subtropical jet in particular was extremely strong, the big difference was the lack of a raging GOA low, so in that aspect it differed. We also saw more MJO in the maritime phases than is typical of a Nino this strong. It was most similar to some of the older analogs like 57-58 and 72-73, but ended up being much warmer since the climate is much warmer now.

[bluewave]

6 minutes ago, GaWx said:

For all practical purposes, I say yes. Actually, for all practical purposes, 1991-2 was a solid super-Nino with a +2.3 trimonthly peak per RONI along with 4 trimonthlies in a row of +2+. So, not just a borderline super.

RONI is not meant to rate the actual El Nino intensity only what the SSTs in other regions were relative to Nino 3.4. 

[LakePaste25]

2 hours ago, bluewave said:

Subsurface continues to warm and Nino 1+2 is still holding at +0.8 for the week. We have a real shot at not reaching a -0.5 trimonthly following the +2.0 peak last year. This would be a first since 1950 for the following year from such a strong El Niño. Global SSTs are almost as warm as last year so this is really inhibiting La Niña development. It will be interesting if this is signaling an era with more frequent El Niños than we have seen since the 1980s when La Nina’s increased over that period. 
 

23-24…..+2.0 peak…lowest so far -0.2

15-16…..+2.6 peak with following year low at -0.7

97-98…..+2.4……-1.6

82-83…..+2.2……-1.0

72-73……+2.1…..-2.0

65-66……+2.0….-0.5

 

https://www.cpc.ncep.noaa.gov/data/indices/

https://www.cpc.ncep.noaa.gov/data/indices/wksst9120.for

20NOV2024     22.7 0.8     25.2 0.1     26.7-0.1     28.8 0.1

The long-term climate models expected us to be in more frequent el niño episodes as SSTs and overall background state warmed. Recently we have seen the opposite - more frequent la niña events. It could be that we will eventually see the expected increase of el niño events, while this recent streak of la niña was just a temporary state. 

[GaWx]

18 minutes ago, bluewave said:

RONI is not meant to rate the actual El Nino intensity only what the SSTs in other regions were relative to Nino 3.4. 

I don’t disagree with what you wrote here from an “official” standpoint or “in name only”. But for all practical purposes, RONI is the more accurate metric imho because of where the SSTs in other tropical regions are is very important to consider.

 I’ll do an extreme hypothetical example to illustrate. Let’s say the average global tropical SST anomaly were +4.5C. And let’s say Nino 3.4 were at +2.3. Officially or in name only it would be a super Nino since it was at +2+. But, for all practical purposes it would actually be a super Niña because 3.4 was 2.2C colder than overall tropical waters. For that metric what’s important is how 3.4 is on a relative basis, which is what I mean by “for all practical purposes.” There’s really nothing El Niño about having a +2.3 in 3.4 other than “in name only” if the surrounding waters are averaging +4.5. In fact it is the opposite.

@PhiEaglesfan712

[Daniel Boone]

22 hours ago, donsutherland1 said:

I suspect that the strengthening PV and lagged response to the development of an AO+/NAO+ will increase the risk for warming late in December. It will take some time to scour out the cold that will dominate during the first half of the month, especially when the PNA is positive.

If we get a +TNH Pattern at regular intervals through the Winter Don we could also wind up with a Feb. 2015 type Pattern at time's. Positive AO/NAO tall PNA Ridge. Eric Webber has brought up a case for that with research backing.

[bluewave]

10 minutes ago, GaWx said:

I don’t disagree with what you wrote here from an “official” standpoint or “in name only”. But for all practical purposes, RONI is the more accurate metric imho because of where the SSTs in other tropical regions are is very important to consider.

 I’ll do an extreme hypothetical example to illustrate. Let’s say the average global tropical SST anomaly were +4.5C. And let’s say Nino 3.4 were at +2.3. Officially or in name only it would be a super Nino since it was at +2+. But, for all practical purposes it would actually be a super Niña because 3.4 was 2.2C colder than overall tropical waters.

It’s like using temperature departures which keep rising every 30 year period. An equally warm month now as many years ago will have a smaller departure relative to the new warmer 30 year baseline. But the actual temperature will be the same. So RONI is more of a relativity index like 30 year climate normals. To me it’s actual temperatures like the Nino 3.4s which have more weight as the means and departures are more relative metrics like RONI. That why I frequently use rankings vs departures. So departures and RONI still have place when weighed against the actual temperatures.

[GaWx]

5 minutes ago, bluewave said:

It’s like using temperature departures which keep rising every 30 year period. An equally warm month now as many years ago will have a smaller departure relative to the new warmer 30 year baseline. But the actual temperature will be the same. So RONI is more of a relativity index like 30 year climate normals. To me it the actual temperatures like the Nino 3.4s which matter and the means and departures are more relative metrics like RONI. 

But if the global tropics were averaging +4.5C but Nino 3.4 were only at +2.3C, why does 3.4 being at +2.3 really matter from El Niño perspective when it is actually a cold area of water relatively speaking and thus should act like La Niña?

[bluewave]

2 hours ago, GaWx said:

But if the global tropics were averaging +4.5C but Nino 3.4 were only at +2.3C, why does 3.4 being at +2.3 really matter from El Niño perspective when it is actually a cold area of water relatively speaking and thus should act like La Niña?

Because as we saw last winter, the 500mb Nino ridge over Canada which drove the record warmth was actually more expansive than much stronger El Niño events like 1997-1998 and 1877-1878. The event was a full fledged super El Niño if you take into account the westward extension of the warmest SSTs near and west of the Dateline and record Nino 4s. This essentially rendered the RONI ineffective last winter as a metric for El Niño strength. We got a super El Niño 500 mb and temperature response over North America and globally. The one possible way RONI worked out was the lower number was reflective of the Niña background which helped to boost the ridge in the East much stronger than past El Niños.

 

 

 

 

[GaWx]

If the global tropics were averaging +4.5C but Nino was only at +2.3C, would you still be thinking of it as a super El Niño other than “in name”? Do you at least see my point?

[PhiEaglesfan712]

To be brutally honest, if the global tropics were averaging +4.5C, I'd be more worried about if the planet was still habitable. For sure, where I currently live would be in the Atlantic Ocean if we reached that point. If the planet was still habitable, I'd probably have moved to West Antarctica by that point.

(And if the global tropics averaging +4.5C and Nino +2.3C scenario happened while I am still living, I'd probably be looking at Eric Webb's Ensemble Oceanic Nino Index to see if he classified it a strong el nino or a strong la nina.)

[Maestrobjwa]

3 hours ago, LakePaste25 said:

The long-term climate models expected us to be in more frequent el niño episodes as SSTs and overall background state warmed. Recently we have seen the opposite - more frequent la niña events. It could be that we will eventually see the expected increase of el niño events, while this recent streak of la niña was just a temporary state. 

Now this is really interesting to me. Now, I'll preface this by saying I'm a layman and amateur weather need. To me, there are some things in weather that just seem so counterintuitive--and the amount of la ninas we've been getting recently always baffled me because common sense would say warming planet, warm waters, more el niño! But then I learned a tad about how trade winds cool the water and it made a little more sense but not a lot. So your saying that it's still possible that we see more ninos?

[GaWx]

The EPO as expected dipped sharply to its lowest level in 13 months after being at its highest since June 4th just 5 days earlier:

2024 11 17  232.92
2024 11 18  182.78
2024 11 19   30.24
2024 11 20 -168.33
2024 11 21 -243.29
2024 11 22 -258.96
2024 11 23 -229.99

[donsutherland1]

8 hours ago, Daniel Boone said:

If we get a +TNH Pattern at regular intervals through the Winter Don we could also wind up with a Feb. 2015 type Pattern at time's. Positive AO/NAO tall PNA Ridge. Eric Webber has brought up a case for that with research backing.

In theory, yes. But a lot would have to happen for such a pattern to actually develop.

[40/70 Benchmark]

December update

https://easternmassweather.blogspot.com/2024/11/december-appears-poised-to-evolve.html

[bluewave]

20 hours ago, Daniel Boone said:

If we get a +TNH Pattern at regular intervals through the Winter Don we could also wind up with a Feb. 2015 type Pattern at time's. Positive AO/NAO tall PNA Ridge. Eric Webber has brought up a case for that with research backing.

We’ll need the Pacific Jet stream and Aleutian Low to back off enough got get a pattern like 13-14 or 14-15. Notice how these features are eroding the western edge of the ABNA pattern. So the ridge axis is getting pushed further east with warmer conditions over NA than during those two winters. It’s still early so there is time for things to change later on. 

13-14 and 14-15 winters weak Pacific Jet and Aleutian Low

Early December forecast stronger Pacific Jet and Aleutian low tucked in near Alaska and ridge axis further east.