When will the multi-decade active era that began in 1995 end?

[Category5Kaiju]

You know, this question was indeed interesting in 2015. Since then:

1. We had an above average season with one of Haiti's worst natural disasters.
2. We had Texas, Florida, and Puerto Rico get impacted by Cat 4 hurricanes.
3. We had a flooding disaster in the Carolinas and a Cat 5 landfall in Florida.
4. We had a Cat 5 landfall in the Bahamas and one of the strongest hurricanes of all time.
5. We had yet another Cat 4 CONUS landfall and two systems that brought devastation to Central America and an end to Greek alphabet naming.
6. We had yet another Cat 4 CONUS landfall.
7. We had Florida's costliest hurricane on record.
8. We had a Cat 3 CONUS landfall.

So, yeah, idk. You tell me what's happening.

[ScottNAtlanta]

We talk about a "27 year" oscillation, but in all honesty, how long have we had real comprehensive ocean data? My guess is that it would be hard to identify 30+- cycles because of that.

[MEANINGLESS_NUMBERS]

Clearly the multi-decade oscillation looks different as the baseline drifts upwards. This is climate change.

[skyline385]

We talk about a "27 year" oscillation, but in all honesty, how long have we had real comprehensive ocean data? My guess is that it would be hard to identify 30+- cycles because of that.

Even the guy who came up with the AMO doesn't believe its an oscillating cycle anymore. The era will probably end sometime but with global warming its not going to be much cooler.

[Category5Kaiju]

I think if I traveled back in time to 2015 and told everybody here that in 5 years the Atlantic would break 2005's NS record and that after that the Atlantic would be no longer using the Greek alphabet, I probably would've been flamed and received a nice stern warning about trolling by the admins

[wxman57]

I've discussed this with Klotzbach. It looked like we went into a cool cycle in 2013. See the link below. However, the tropics kept spiking warm every summer. Quite different from the previous cool cycle.

http://wxman57.com/images/AMO.jpg

[Teban54]

I've discussed this with Klotzbach. It looked like we went into a cool cycle in 2013. See the link below. However, the tropics kept spiking warm every summer. Quite different from the previous cool cycle.

http://wxman57.com/images/AMO.jpg

http://wxman57.com/images/AMO.jpg

Judging from this chart alone, could it be that the "cool cycle" only lasted about 10 years (2013-2022) before returning to the warm cycle in 2023? Also, given the activity of these years (especially since 2016) that are unmatched in previous -AMO eras, perhaps even the -AMO "era" much more active now than they previously were?

(All this is assuming we had a cool cycle in the first place.)

[MEANINGLESS_NUMBERS]

I've discussed this with Klotzbach. It looked like we went into a cool cycle in 2013. See the link below. However, the tropics kept spiking warm every summer. Quite different from the previous cool cycle.

http://wxman57.com/images/AMO.jpg

http://wxman57.com/images/AMO.jpg

Judging from this chart alone, could it be that the "cool cycle" only lasted about 10 years (2013-2022) before returning to the warm cycle in 2023? Also, given the activity of these years (especially since 2016) that are unmatched in previous -AMO eras, perhaps even the -AMO "era" much more active now than they previously were?

(All this is assuming we had a cool cycle in the first place.)

The baseline is rising.

[NotSparta]

I've discussed this with Klotzbach. It looked like we went into a cool cycle in 2013. See the link below. However, the tropics kept spiking warm every summer. Quite different from the previous cool cycle.

http://wxman57.com/images/AMO.jpg

http://wxman57.com/images/AMO.jpg

Reminds me of the +PDO in the 2010s. It does exist there but ends rather quickly as we are evidently not in -AMO anymore (in agreement with the graph)

[Teban54]

I am bumping this thread not because I want to argue the answer is any recent year nor that we're in a new -AMO era, but solely as a response to this comment in the latest 2024 thread, as I feel the point about AMO is distracting for that discussion.

I'm usually an extremely bullish forecaster, but the fact that recent seasons, and especially this one, have been so strange is making me wonder whether the AMO is beginning to flip. Maybe 2018 was the last positive AMO year? It would line up with 1969, another year with a Category 5 landfall on the Gulf coast, as the end of its own AMO+ era.

I'm not sure what the state-of-the-art measure of AMO is, but I found two sources from a quick Google: CSU's index and NOAA's index. Here's the CSU table since 2017:



Almost all years had non-negative AMO in August and September, with the sole exception of -- guess what -- 2018. The only other year that had negative CSU AMO in Oct/Nov is 2020, but those two months gave us the most active late season on record. In comparison, during the last -AMO era (1970-1994), only two years had non-negative CSU AMO in September: 1981 and 1987.

The NOAA index seems a lot more positive than CSU's (it had never dropped below 1 since May 2023, for example). But using the NOAA index makes the trend even clearer: The last month that had a negative NOAA AMO was December 1996, and no individual month in the last -AMO era had NOAA AMO above 1 like we have just experienced for 15 months in a row.

The caveat is that I'm not sure how much either index accounts for global warming. It looks like NOAA's index may be more prone to it than CSU's. But combining both indices and the fact that SSTAs for two years in a row have resembled a strong +AMO pattern, I can't see how we're anywhere close to -AMO.