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

[GeneratorPower]

:uarrow: The fact that the 30s through the 60s were more active than the 70s and 80s? And thus the correlation with seasonal activity with AMO? Plus we have recon going back to 1943 and also the ATL hurricane re-analysis.

Statistics, for example, requires a sample size significantly larger than the standard deviation to be meaningful. Basically we are attempting to draw conclusions about 30-40 year periods of time using only 80 years of historical record. This, to me, is questionable. Sure, you might seem to discover a pattern but it could be noise. There's no way to be sure. The solar cycle, on the other hand, is very cyclical. It clearly runs on an 11 year cycle. There have been enough cycles observed to be sure that it's an 11 year cycle. But you cannot be sure that a 30 year cycle is really a cycle if you're only looking at 60, 70, or even 90 years of record. It might not be a true cycle at all. Or it might be a cycle that is caused by another weather or geological phenomenon. Someone that observes my daily driving habits for only three days might draw a mistaken conclusion of how often I go to the grocery store.

[Yellow Evan]

:uarrow: The fact that the 30s through the 60s were more active than the 70s and 80s? And thus the correlation with seasonal activity with AMO? Plus we have recon going back to 1943 and also the ATL hurricane re-analysis.

Statistics, for example, requires a sample size significantly larger than the standard deviation to be meaningful. Basically we are attempting to draw conclusions about 30-40 year periods of time using only 80 years of historical record. This, to me, is questionable. Sure, you might seem to discover a pattern but it could be noise. There's no way to be sure. The solar cycle, on the other hand, is very cyclical. It clearly runs on an 11 year cycle. There have been enough cycles observed to be sure that it's an 11 year cycle. But you cannot be sure that a 30 year cycle is really a cycle if you're only looking at 60, 70, or even 90 years of record. It might not be a true cycle at all. Or it might be a cycle that is caused by another weather or geological phenomenon. Someone that observes my daily driving habits for only three days might draw a mistaken conclusion of how often I go to the grocery store.

We have more than 80 years of historical record. Much closer to 200-250 years.

From Wikipedia...

"Although more uncommon since 1995, few above-normal hurricane seasons occurred during 1970–94.[68] Destructive hurricanes struck frequently from 1926–60, including many major New England hurricanes. Twenty-one Atlantic tropical storms formed in 1933, a record only recently exceeded in 2005, which saw 28 storms. Tropical hurricanes occurred infrequently during the seasons of 1900–25; however, many intense storms formed during 1870–99. During the 1887 season, 19 tropical storms formed, of which a record 4 occurred after November 1 and 11 strengthened into hurricanes. Few hurricanes occurred in the 1840s to 1860s; however, many struck in the early 19th century, including an 1821 storm that made a direct hit on New York City. Some historical weather experts say these storms may have been as high as Category 4 in strength.[69]"

[wxman57]

We don't have 250 years of accurate MJO (ocean temp) obs, nor do we have such a record of storms at sea (prior to satellite).

[cycloneye]

Someone has mentioned about this question in a post so I am bumping this to have more healthy discussions about this important topic/question.

[Hammy]

I said last year this year would be the telling year, and it's looking increasingly like we're headed out of it.

[AxaltaRacing24]

IMHO there is one reason why the ATL has struggled in the past few years. The PDO is still positive. Until that crashes again in the next series of La Nina's, we won't see 2000s like activity year after year.

[WeatherEmperor]

IMHO there is one reason why the ATL has struggled in the past few years. The PDO is still positive. Until that crashes again in the next series of La Nina's, we won't see 2000s like activity year after year.

Good point. Is there any data that suggests if the PDO will go down again? It appears it has set a record for consecutive months in positive. When can we see it go down again?


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[Andrew92]

I thought I read recently though that the overall ACE up to this point is pretty close to average, and if below average at all not by much? I know the MDR looks unfavorable overall, but I am still watching what may happen closer to home, especially in September, before saying this active era has ended.

Besides, last year got fairly busy by the end. Mostly on the strength of three storms admittedly (one in November at that), but still....

I may be stubborn, but I still think we can't say the active era is over yet at the very least.

-Andrew92

[cycloneye]

IMHO there is one reason why the ATL has struggled in the past few years. The PDO is still positive. Until that crashes again in the next series of La Nina's, we won't see 2000s like activity year after year.

Good point. Is there any data that suggests if the PDO will go down again? It appears it has set a record for consecutive months in positive. When can we see it go down again?


Sent from my iPhone 7 using Tapatalk

Our friends Kingarabian and Ntxw know a lot about the PDO and will answer the question.

[AxaltaRacing24]

I thought I read recently though that the overall ACE up to this point is pretty close to average, and if below average at all not by much? I know the MDR looks unfavorable overall, but I am still watching what may happen closer to home, especially in September, before saying this active era has ended.

Besides, last year got fairly busy by the end. Mostly on the strength of three storms admittedly (one in November at that), but still....

I may be stubborn, but I still think we can't say the active era is over yet at the very least.

-Andrew92

This also ties into the my earlier post and what Alyono said last year. Once the PDO crashed, this basin came to life. If we get an entire season with a weak Nino and a negative PDO with a SST pattern like this, look out.

[CYCLONE MIKE]

I didn't go back and read this thread but I'm sure I posted somewhere in there that I thought it had ended. In fact like I mentioned to Steve the other night, imo the gulf is the first to feel the full brunt of it but think it ended in 2008 not 1995. I can't post pictures on here anymore from my photobucket site but the maps of origin and tracks up til 2008 compared to 2008- current is almost unbelievable. And yes I know you can a couple more in the current list but they were weak short lived and/or buried deep down in the bay of Campeche.

https://www.google.com/search?ei=EZKYWa ... zszIioxJ5M

[CyclonicFury]

Well, with Harvey, we now are at 8-3-1 for the season. ACE levels are only near average since most of the storms have been short lived. The MDR has remained quiet so far but that could change next week. I'm personally not convinced the active era is over yet. Just because we had Harvey does not necessarily mean the entire season will be active, but 8-3-1 is definitely active through this point in the season. Some seasons during the last quiet phase had activity similar to that for the entire season. Last season was active, just backloaded. 2015 was somewhat active for a Super El Niño. If you look at the MDR SSTs, they are very warm relative to normal, which usually indicates +AMO. I personally think the active era of the Atlantic is still going, just maybe not as "active" as the 2003-05 period.

[AxaltaRacing24]

Well, with Harvey, we now are at 8-3-1 for the season. ACE levels are only near average since most of the storms have been short lived. The MDR has remained quiet so far but that could change next week. I'm personally not convinced the active era is over yet. Just because we had Harvey does not necessarily mean the entire season will be active, but 8-3-1 is definitely active through this point in the season. Some seasons during the last quiet phase had activity similar to that for the entire season. Last season was active, just backloaded. 2015 was somewhat active for a Super El Niño. If you look at the MDR SSTs, they are very warm relative to normal, which usually indicates +AMO. I personally think the active era of the Atlantic is still going, just maybe not as "active" as the 2003-05 period.

I did not follow the hurricane seasons with as much detail back then so until 2016 I was unfamiliar with the 2015's specific conditions besides the nino. After looking into it I still cannot believe it was as active as it was. People were discussing a possibility of 5-1-0 that year and we still had 2 majors and 4 hurricanes. We even beat 2014 in named storms. Crazy

[Kingarabian]

IMHO there is one reason why the ATL has struggled in the past few years. The PDO is still positive. Until that crashes again in the next series of La Nina's, we won't see 2000s like activity year after year.

Good point. Is there any data that suggests if the PDO will go down again? It appears it has set a record for consecutive months in positive. When can we see it go down again?


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Since it appears we're transitioning into a cool-neutral and the latest PDO was only +0.10, we could soon see the monthly values dip back into negative territories again. But we'll likely have to wait until next summer to see if the PDO is transitioning out of the warm phase and into a cool phase.

But I don't know if the PDO can be used to gauge Atlantic activity since 2005 for the most part was situated in a warm PDO phase. And we know how that season went.

[Macrocane]

How can some people be sure that the high activity era has ended when 2016 was a fairly active season with 4 major hurricanes?

[CyclonicFury]

How can some people be sure that the high activity era has ended when 2016 was a fairly active season with 4 major hurricanes?

Personally I don't think it's over. 2013 was unfavorable globally and 2014 and 2015 were under the influence of a Super Niño. 2016 was active and so far 2017 has been active as well.

[Dean_175]

I admit that I do not know much about the AMO, but per this data (unsmoothed): https://www.esrl.noaa.gov/psd/data/correlation/amon.us.long.data the AMO has not returned to pre-1995 values (which were by and large consistently negative)--so if you support the idea that the active eras correlate with positive AMO phases, then I do not think we are seeing that. On the other hand, there are multiple ways in which the AMO can be defined.

The state of the Pacific the past several years may be a factor (though not in 2013). A lot of warmth in the tropical Pacific since 2014. Even during the La Nina last year, cool anomalies were very localized to the equator- with the rest of the tropical east/central Pacific being warmer than average.

Remember, while PDO is defined by the SST profile north of 20 degrees- the actual signature of PDO anomalies extend into the tropics. PDO has been consistently positive for over 3 years now.

[Macrocane]

So, is it?


I think it's safe to say that we're still in the active phase, with last year and this year there's no doubt about it.

[CyclonicFury]

So, is it?


I think it's safe to say that we're still in the active phase, with last year and this year there's no doubt about it.

I think we finally have our answer. 2013 was an anomaly year in which the global tropics struggled for the most part. 2014 and 2015 were under the influence of El Nino, yet still weren't really all that quiet (just slightly below normal ACE). 2016 was above average and 2017 is likely to end up even more above average compared to 2016. The seasonal total is at 11-4-2 with 61 ACE already on September 6th. This is more active than many seasons from the 1970-1994 quiet phase and we're only about halfway through the season. Jose and Katia are likely to become hurricanes, and Jose also has potential to become a major hurricane, which could put the seasonal total at 11-6-3. Models are also suggesting the possibility of two more MDR storms in the next 10 days. We could reach 100 ACE as well within the next week.

[Steve]

I said last year this year would be the telling year, and it's looking increasingly like we're headed out of it.

Oops