2024-2025 La Nina

[raindancewx]

Atlantic still has a long way to go to be anywhere near average for ACE. We're running more than 20% below average still and that's after a very fast start. The season after Beryl has been extremely inactive. It's Beryl and then less than 40 ACE otherwise. 

Isaac & Joyce will both die Sunday/Monday. Neither is going to add very much ACE in the short term. The formula is sustained winds in knots squared measured every six hours (UTC time) divided by 10,000. You're looking at 3-5 ACE per day for another two days or so from those storms. At that point we're around 80 ACE with 94 as average through 9/30. It doesn't look like there is anything that will be strong enough imminently to bump up ACE quick after Isaac dies. So entering October we probably start to fall behind relative to average again. Early October still sees ACE go up by 1 point or so per day. 

October averages 20-25 ACE so even in a bit of a dead season you should see some tropical activity.

My general rule is September + 60 ACE is a pretty safe ceiling. It's very rare to get anywhere near 60 ACE in Oct-Nov. So we're almost certainly looking at 80-140 for the season. Still think we could finish as low as 90 ACE but 100-110 is probably a better bet now. Since 1850 (170+ years) it's like seven hurricane seasons with 60+ ACE for Oct-Nov. Even for the 1991-2020 period which is mostly the warmed up, warm AMO, it's still only 2005, 2016, 2020 (3/30 years) or 10%. The 2016 season had Matthew (cat 5) and Nicole (cat 4) form in late Sept/early Oct and carry on for a while after an inactive start. Matthew was a 4/5 in October for like five days which is nuts. That's probably the best case for those of you who want the hyperactive ACE totals. But I don't expect to see multiple long-duration cat 4+ storms in early October this year.

[snowman19]

4 minutes ago, raindancewx said:

Atlantic still has a long way to go to be anywhere near average for ACE. We're running more than 20% below average still and that's after a very fast start. The season after Beryl has been extremely inactive. It's Beryl and then less than 40 ACE otherwise. 

Isaac & Joyce will both die Sunday/Monday. Neither is going to add very much ACE in the short term. The formula is sustained winds in knots squared measured every six hours (UTC time) divided by 10,000. You're looking at 3-5 ACE per day for another two days or so from those storms. At that point we're around 80 ACE with 94 as average through 9/30. It doesn't look like there is anything that will be strong enough imminently to bump up ACE quick after Isaac dies. So entering October we probably start to fall behind relative to average again. Early October still sees ACE go up by 1 point or so per day. 

October averages 20-25 ACE so even in a bit of a dead season you should see some tropical activity.

My general rule is September + 60 ACE is a pretty safe ceiling. It's very rare to get anywhere near 60 ACE in Oct-Nov. So we're almost certainly looking at 80-140 for the season. Still think we could finish as low as 90 ACE but 100-110 is probably a better bet now. Since 1850 (170+ years) it's like seven hurricane seasons with 60+ ACE for Oct-Nov. Even for the 1991-2020 period which is mostly the warmed up, warm AMO, it's still only 2005, 2016, 2020 (3/30 years) or 10%. The 2016 season had Matthew (cat 5) and Nicole (cat 4) form in late Sept/early Oct and carry on for a while after an inactive start. Matthew was a 4/5 in October for like five days which is nuts. That's probably the best case for those of you who want the hyperactive ACE totals. But I don't expect to see multiple long-duration cat 4+ storms in early October this year.

Would not surprise me at all to see a final Atlantic ACE of 90-110 come 11/30

[GaWx]

4 hours ago, bluewave said:

My guess is that the uptick in tropical activity is related to the Atlantic warming in the last few weeks. Notice how the Atlantic was the warmest early in the season for Beryl and then dropped during the lull through August. Could be related to the lapse rates improving as the upper atmosphere differential probably wasn’t as great and the stability dropped. So we have a shot at finishing the season over 100 ACE which would be closer to average. We also had a lull during August 2022 and then an increase in September like this year. That year featured Ian in the Gulf during September and this year Helene.

 

Warming surface decreased the delta from the upper levels to surface allowing more development.

 

 

 

I think that regarding decreasing stability that the much lower SSN should be considered as a possible contributor. Keep in mind that Aug was way up at 215 and that it still was quite high into early Sep:

2024 09 01 2024.668 182  14.2  29  37
2024 09 02 2024.671 195  20.7  26  33
2024 09 03 2024.673 180  21.2  20  23
2024 09 04 2024.676 174  26.1  21  26
2024 09 05 2024.679 182  13.4  16  21
2024 09 06 2024.682 189  13.3  20  25
2024 09 07 2024.684 168  17.5  25  30
2024 09 08 2024.687 171  18.7  20  26
2024 09 09 2024.690 157  19.2  24  27
2024 09 10 2024.693 149  12.9  25  31
2024 09 11 2024.695 153  15.4  29  34
2024 09 12 2024.698 145  11.8  25  29
2024 09 13 2024.701 118  12.8  27  32
2024 09 14 2024.704 116  11.4  25  32
2024 09 15 2024.706 102  14.7  26  31
2024 09 16 2024.709 142  16.2  22  27
2024 09 17 2024.712 141  13.0  30  38
2024 09 18 2024.714 110   8.6  28  33
2024 09 19 2024.717 109  12.1  34  42
2024 09 20 2024.720 126  13.0  29  35
2024 09 21 2024.723 131   9.6  20  26
2024 09 22 2024.725 144  13.7  13  17
2024 09 23 2024.728 130   7.4  20  26
2024 09 24 2024.731 141  12.2  20  24
2024 09 25 2024.734 141   9.0  20  25
2024 09 26 2024.736 145  15.8  18  22

[40/70 Benchmark]

2022 is an outstanding analog....no analog will be perfect, so dismiss it at your own peril.

[roardog]

1 hour ago, 40/70 Benchmark said:

2022 is an outstanding analog....ni anamog will be perfect, so dismiss it at your own peril.

I think you might have said this before too but that winter with a less amplified trough west/ridge east would actually be a very interesting winter here and possibly for you too.

 

 

[binbisso]

@bluewave you were monitoring the mjo in october for clues about this coming winter. With October starting in phase 1 and ending in the COD mid month does this give you any hints regarding winter 

[jm1220]

Just now, roardog said:

I think you might have said this before too but that winter with a less amplified trough west/ridge east would actually be a very interesting winter here and possibly for you too.

 

 

I mean if we could actually have a standalone Greenland block that doesn't become part of the insane/steroidal SE Ridge, that would be a good thing for many. It was jaw dropping that "winter" how that happened multiple times. It was just one horrible feedback mechanism after another that kept screwing us. But as is the case in most Ninas, further north in New England was perfectly fine and even very snowy. The north cutting storms eventually hit cold enough air somewhere in upstate NY and New England and start dumping. In 07-08 that gradient was S of I-90, 22-23 season much further north because of that SE ridge. 

[qg_omega]

17 minutes ago, binbisso said:

@bluewave you were monitoring the mjo in october for clues about this coming winter. With October starting in phase 1 and ending in the COD mid month does this give you any hints regarding winter 

4-5-6 all winter

[mitchnick]

1 hour ago, 40/70 Benchmark said:

2022 is an outstanding analog....ni anamog will be perfect, so dismiss it at your own peril.

 

[mitchnick]

30 minutes ago, binbisso said:

@bluewave you were monitoring the mjo in october for clues about this coming winter. With October starting in phase 1 and ending in the COD mid month does this give you any hints regarding winter 

I think he was focusing on the strength of it.

[PhiEaglesfan712]

2 hours ago, raindancewx said:

The 2016 season had Matthew (cat 5) and Nicole (cat 4) form in late Sept/early Oct and carry on for a while after an inactive start. Matthew was a 4/5 in October for like five days which is nuts. That's probably the best case for those of you who want the hyperactive ACE totals. But I don't expect to see multiple long-duration cat 4+ storms in early October this year.

2016 ended with 15/7/4 and 140 ACE. I think those are the upper end numbers for this year.

[George001]

5 hours ago, PhiEaglesfan712 said:

07-08 is probably the top analog right now. That year, we had just the 2 big storms (Dean and Felix) like we do this year (Beryl and Helene). Also, the la nina development took off right about this time in 2007, and though we will likely not reach the ONI strength of that year, the MEI/RONI are a near perfect match. Not to mention, 07-08 was a central based, modoki la nina. Only thing really going against it was that 07-08 was near a solar minimum, while we are currently near a solar maximum.

22-23 was a dissipating la nina, which is opposite of what we have this year.

I have 2022-2023 as my #1 analog right now mainly due to the extreme -PDO, solar, and I like the ENSO match for both strength and structure (moderate modoki). However, I do agree that 07-08 is also a good analog (my #2 annalog) and that the Atlantic hurricane season is closer to 07-08 than 22-23. It’s too early to make a forecast but I’m definitely going to heavily weight both of those years and do a blend of some sort with other years that I like. 

[George001]

3 hours ago, snowman19 said:

Would not surprise me at all to see a final Atlantic ACE of 90-110 come 11/30

In my opinion 90 is too low, I’m thinking around 120-130. I could be wrong though, I expected 200+ ACE before the season started and that clearly isn’t going to happen. You had the right idea, good call with the skepticism of a hyperactive season. The gfs is fairly aggressive but like you and Raindance said, fairly big hole to climb out of.

[George001]

2 hours ago, 40/70 Benchmark said:

2022 is an outstanding analog....ni anamog will be perfect, so dismiss it at your own peril.

Completely agree with all of this. You can nitpick any analog, but dismissing the bigger picture because a couple minor details don’t match would be a mistake. Yeah the ACE might be a bit higher and we are coming off a strong Nino instead of a moderate Nina, but I don’t see that as a good reason to discount 2022-2023. It’s an excellent match for ENSO strength, warm Atlantic, ENSO structure, and the strong -PDO. Another big factor that 2022-2023 has going for it is climate change (2022-2023 was only 2 years ago, so a more similar climate to today than older analogs). Thats not something that should be ignored just because a couple other things don’t line up.

[snowman19]

1 hour ago, George001 said:

In my opinion 90 is too low, I’m thinking around 120-130. I could be wrong though, I expected 200+ ACE before the season started and that clearly isn’t going to happen. You had the right idea, good call with the skepticism of a hyperactive season. The gfs is fairly aggressive but like you and Raindance said, fairly big hole to climb out of.

I’m starting to get a good idea of where we are headed for winter. Going to wait until the beginning of November to make a final guess and write something up here, but safe to say my analogs are not going to be 83-84, 95-96, 10-11, 13-14, 17-18 or 20-21……

[George001]

59 minutes ago, snowman19 said:

I’m starting to get a good idea of where we are headed for winter. Going to wait until the beginning of November to make a final guess and write something up here, but safe to say my analogs are not going to be 83-84, 95-96, 10-11, 13-14, 17-18 or 20-21……

Yeah I wouldn’t choose any of those as my top analogs either, but I do think there is an important distinction to make. I don’t think there is anything terribly wrong with 13-14, 20-21 and 10-11. I wouldn’t weigh them as heavily as 2022-2023 and 2007-2008, but I do think they have some value as analogs. 95-96, 17-18 and 83-84 absolutely not. If anything, 95-96, 17-18 and 83-84 are such horrible analogs they may have more utility than the first 3 years by including them but as anti logs. Especially 95-96, that was a raging +PDO and east based Nina and I’m pretty sure solar is also opposite to this year. I don’t even think Joe Bastardi is using 95-96 as an analog. 

[Stormchaserchuck1]

The GFS ensemble mean now has a >594dm ridge over Japan in the medium range! I think this could be record breaking by a little bit. It's part of a strong +WPO pattern, which I said would be more likely to happen this October earlier in this thread (because of the Winter +NAO tendency projection and -PDO). 

This is how a +WPO October rolls forward to the Winter across the CONUS

December

January

February

January has a pretty good +NAO match.. which I have seen with a few different things, like -PNA conditions in September.. this could be the month where -PNA/+EPO conditions ease up. 

[raindancewx]

The low Atlantic ACE thing in a September La Nina (it tends to be around 60) is interesting to look at. I know you all like 2022. But we had major cold waves in the West in November. Don't really expect that this year. But I do see evidence for a lot of cold days again (relatively) for a La Nina locally with ACE remaining low. This is mostly because our dew points have been consistently running much lower than in 2022 so lows should get very cold at times.

If you notice six of the nine the inactive Septembers for Atlantic ACE in La Ninas tend to follow El Ninos (1983, 1970, 1973, 2016 2007, 1954).

You can see that Jan/Feb are the most likely months to see a lot of cold days in a low Sept ACE / 70-130 ACE type hurricane season. September ACE has fairly weak correlations to monthly highs in La Nina here. But it does correlate somewhat strongly with January (r-squared is about 0.3). It's actually been quite a while since we've had a La Nina with an inactive September. In 2022, September was pretty active.

October actually looks pretty different from 2022 anyway. It's going to be pretty warm down here if you buy into the models in October. In 2022 it was warmest in the Northwest not the Southwest. The cool/average spot shown on the CFS is also fairly off from 2022 when it was chilly in the South.

[Stormchaserchuck1]

The Summer Hurricane season has nothing to do with the Winter, except for larger macro factors that correlate both things.  People use it because it's an easy data point, but sometimes you have to think about the physics of meteorology.  Storm systems would have circled the globe 3x by the time the Winter is here. 

[raindancewx]

Honestly the WPO definition is 50-70N minus 25-40N for 140E-150W. It doesn't look negative for October but what the CFS shows is neutral. You have a mix of strong heights and neutral heights in the north and then consistently low heights to the south.

I'm still expecting a mixed bag of WPO conditions in the winter. I don't think its very likely we see the Feb/Mar 2023 type of WPO without a transition to an El Nino. So my guess would be +/= WPO early in winter then =/- later on. 

 

[Stormchaserchuck1]

4 minutes ago, raindancewx said:

Honestly the WPO definition is 50-70N minus 25-40N for 140E-150W. It doesn't look negative for October but what the CFS shows is neutral. You have a mix of strong heights and neutral heights in the north and then consistently low heights to the south.

I'm still expecting a mixed bag of WPO conditions in the winter. I don't think its very likely we see the Feb/Mar 2023 type of WPO without a transition to an El Nino. So my guess would be +/= WPO early in winter then =/- later on. 

 

You can see by my post above that the WPO tends to reverse for December, and sometimes January. In all the historical data, this reversal does tend to happen on different time scales. I think that we have seen 5/6 +WPO Winters, with one being neutral means it's somewhat unlikely to happen as a mean again this year.  I think you have been intuitively saying this for a while. 

[raindancewx]

I don't think the WPO is going to show up positively on the index in October. The type of huge heat we're forecast to see in the West in October is antithetical to +WPO conditions in Fall/Spring.

From what I can see there are also three major problems with 2022-23:

- It rapidly collapsed into an El Nino in Feb-Apr 2023. Not looking likely with this event.

- It was much weaker than the prior two La Ninas. Y/Y warming in Nino 3.4 favors Western cold. There are exceptions after two El Ninos in a row (1959/1978/1988/2016/2020) but it does generally hold up. We have massive y/y cooling.

- MJO/harmonics timing features are off on everything.  ITCZ placement, monsoon development, hurricane activity timing - all the stuff triggered by waves from the tropics is off a bit. 2022 was pretty active for Atlantic hurricanes in September, and it had a very strong monsoon in MX and the SW US as a few examples. Getting MJO phase 5 or whatever 30-days off from 2022 would be a different pattern.

In a more mechanical sense the SST profile is much colder in the MJO 4-6 zones, North Atlantic, North Pacific, and tropical Atlantic. On the flip side, the La Nina development is way behind. With the tropical Atlantic and Indonesian waters colder, I'd also imagine the RONI effect is diminished since it is subtracting out global tropical heat content as a global warming signal.

[Stormchaserchuck1]

This is what a +WPO looks like in October

This is what models are showing

[raindancewx]

I don't know why you're so adamant about this. My point for months has been that the North Pacific would look different than prior years, and the models do show that.

Look at Oct 2021, which +1.7 for the index. https://psl.noaa.gov/data/correlation/wp.data

You're supposed to have low pressure north of high pressure in the NW Pacific for a +WPO.

Now look at the forecast. You have generalized high pressure everywhere. Again, it's 25-40N v. 50-70N. If you smooth out the reds, there isn't much of a difference between the two, which means the index isn't going to be positive. It's nothing like 2021 or 2022 if the forecast is anywhere near right.

[Stormchaserchuck1]

It's not a big deal.. I know right off the coast of Japan is the south part of the West-Pacific indexes measurement, and they are going to break their record by a lot so it's kind of exciting to have such a good data point at play. GFS ensembles have negative anomalies over Siberia when this happens, but maybe not later in the month, but the index will be strongly positive for at least a few days. The roll forward matches what other things are showing too, so it all fits together as part of a pattern. 

[snowman19]

One thing is for sure, this La Niña definitely looks like a central-based/CP event now. The only cold subsurface water left is in region 3.4 @40/70 Benchmark




 

[mitchnick]

2 hours ago, snowman19 said:

One thing is for sure, this La Niña definitely looks like a central-based/CP event now. The only cold subsurface water left is in region 3.4




 

You got married in March, if I'm not mistaken. You should be in bed with your bride at 3 or 4 in the morning instead of posting here! Lol

[snowman19]

1 minute ago, mitchnick said:

You got married in March, if I'm not mistaken. You should be in bed with your bride at 3 or 4 in the morning instead of posting here! Lol

Sorry, I work double shifts to pay off all the loans I took out for that wedding

[bluewave]

The Pacific heading into October is fairly close to 2022 with a strong Aleutian Ridge and Western US Ridge. But the NAO is more negative this time. We’ll have to see how the rest of the month goes since it’s tough to forecast the whole month based on an early snapshot.

 

 

[so_whats_happening]

23 hours ago, bluewave said:

We got Debby back in early August during the last favorable MJO interval, but Helene was much more intense this week. My guess is that the warming surface SSTs relative to the higher atmosphere allowed a more unstable storm environment. I was pointing this out back during the August lull that a storm getting into the Gulf had a chance of really taking off due to the record SSTs. Notice the SST warming pulse just prior to Helene in the Gulf like we saw with the entire Atlantic basin. There were comments back in early August how people were surprised that the favorable MJO interval back then didn’t lead to another major hurricane like Beryl.

This storm was very much how Michael developed 6 years ago and had such a better opportunity to go all out then Debby did due to track, If Debby had a little less land interaction initially like Helene did it could have done similar. 

 This was the Satellite loop for Debby when it got the opportunity to get going into the Gulf. 

https://rammb-data.cira.colostate.edu/tc_realtime/loop.asp?product=4kmirimg&storm_identifier=al042024&starting_image=2024al04_4kmirimg_202408021340.gif&ending_image=2024al04_4kmirimg_202408051806.gif

Ernesto did pretty well but came up just short too for a major hurricane, surprisingly VP was not good for a phase 1 passage. So location of the storm being east of the warmest regions limited the overall strength with that system. Here is the VP of Debby, Ernesto, and Helene. The VP overall this summer has been against us from opening the Atlantic up fully but these weak breaks in the overall positive VP setup from 7/1- 8/31 have yielded several storms.