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

[1900hurricane]

I am currently in the process of tabbing out all sorts of basin data, by the way. I started mostly with the more active years, but I'm slowly making progress filling it in. What I have done so far is posted below, and I'll probably do a repost once I've got everything complete going back to at least 1995.

[Ntxw]

Thanks for sharing your data 1900hurricane! ACE is such a great tool especially when you can dig in further with the numbers and can truly tell much more of the story.

[FireRat]

This weird season could make it or temporarily break it when it comes to showing that the multi-decadal cycle is winding down.

It's been a year of a lot of weakness thus far, thanks to the shear and dry air...but we have managed to get 11 named systems by 9/17 and plenty of season left. If we get, say 3, strong hurricanes later this month and next to up the ace, we may have another very busy year in the charts. It seems quite 2011 and 2012-ish so far...and those years featured strong storms in October.

Just my opinion, I wonder how things will look by November. Fun times ahead perhaps.

[Andrew92]

Here is another thought that has crossed my mind. Before 1995, the most recent years with at least two major hurricanes south of 20 degrees were 1988 and 1989. And before then, you have to go back to at least 1969 for the last such instance.

That is if Debbie and Francelia both stand as majors, and given their pressures, that is not a lock. Debbie was at 969 mb as it approached 20 degrees and Francelia was at 973 in the Caribbean. These two storms would have to be pretty small to stand as legit category 3's. Before then, 1961 was most recent allegedly. Hattie was legit, but I have serious doubts about Anna being a Caribbean major. Storms like Carla and Esther were majors, but didn't become so until north of 20 degrees.

From 1995 through 2010, the only years with fewer than two majors south of 20 degrees were all El Nino years: 1997, 2002, and 2006 (none of these years had one in those low latitudes either). Since 2011, there have been three majors south of 20 degrees, and all were very brief in their duration. Rina and Danny also were small in size and had higher pressures than normal for major hurricanes. Sandy only became a major as it approached 20 degrees, though its pressure fell just barely below 965 mb (recommended by the Saffi/Simpson scale) a few hours before that approach.

Mind you, we still haven't seen a true La Nina year after an El Nino, where all of the EPAC was relatively cold, since 2010. But it is telling that 2011, still a short distance after the 2009 event, had little activity in the low latitudes. We arguably haven't had such a dearth of major hurricane activity south of 20 degrees in six straight years since the 1980s, when there were zero majors between 1981-86 in those latitudes. You can't entirely look at El Nino either, as 1984 was a rock solid La Nina. Or 1990-94, when the EPAC was warm for a very extended period of time.

My jury overall as a result is still out if the active Atlantic period is over. Once we have a truly cold La Nina year, and not just at the Equator, I think we will have a very good answer.

-Andrew92

[tolakram]

Posted this in the seasonal indicators thread but it probably belongs here as well.



From this tweet.

 https://twitter.com/philklotzbach/status/779014884063268864

[Macrocane]

The activity in the Atlantic in the last few days adds more uncertainty to the question.

[centuryv58]

The activity in the Atlantic in the last few days adds more uncertainty to the question.

Not sure the Atlantic is losing any sleep over this issue. Science knows much less about long term patterns or non patterns than I'd like to ponder deeply, but it passes time between storms to yak about it.

[wxmann_91]

The activity in the Atlantic in the last few days adds more uncertainty to the question.

Quiet periods have had strong hurricanes and active spikes too. (Think David/Frederic 1979)

[Ptarmigan]

The activity in the Atlantic in the last few days adds more uncertainty to the question.

Even in active cycles, there have been less active seasons. Vice versa in less active cycles with more active seasons.

[Hammy]

Matthew and Nicole I think represents a return to the pre-2012 state of the atmosphere, the Nino effects fading after a 2012-esque difficulty earlier in the season, which also had quasi-Nino/+PDO issues.

[Ptarmigan]

Matthew and Nicole I think represents a return to the pre-2012 state of the atmosphere, the Nino effects fading after a 2012-esque difficulty earlier in the season, which also had quasi-Nino/+PDO issues.

I am thinking that too. Of course we will have to see starting in 2017.

[1900hurricane]

Here's my data for the Atlantic Basin back to 1995 now that I've completed my work that far back. There are a lot of things one would expect, but also some surprises as well, particularly amongst the stats independent of storm count. Unsurprisingly, 2013-2015 were down years, but the few years leading into them saw a marked decline in ACE/TS Day and PDI/TS Day. The numbers so far this year (in the header row and not counted in the derived data) have rebounded very close to the 1995-2015 mean almost across the board. 2013 is pretty clear cut the least active year of the bunch (PDI <20!), and 2005 is the most active as far as storm count dependent numbers are concerned. When it comes to the storm count independent numbers though, 2004 far and away takes the cake. I realize there is little point in this train of thought due to the chaotic nature of the atmosphere, but part of me wonders how active 2004 could have been without El Nino and holding everything else constant. Unlike 2005, which was spread out over a longer time span, 2004 was basically a two month season, probably in part due to El Nino. September 2004 was particularly special. The 154.9 ACE and 160.8185 PDI are the highest monthly numbers I've yet encountered globally.



Next on my plate for the Atlantic is to work back to at least 1979 and start filling in climatic data such as ENSO, AMO, PDI, and so on to try and find if any correlations exist. It may take me quite a while to do that though. I've also been doing the same thing for the WPac for quite a while now (in the process of working back to at least 1977), and I'm also planning on starting a similar sheet for the EPac. So much data to go through, so little time!

[cycloneye]

There is not a clear picture about if the active era ended or not.Let's see how the 2017 season plays out.

 https://twitter.com/EricBlake12/status/807367427591929857

[Ntxw]

That is some great work 1900hurricane. I didn't realize what an anomaly 2004 was. We appreciate your work and hope you will continue to share your research with us.

[Ptarmigan]

That is some great work 1900hurricane. I didn't realize what an anomaly 2004 was. We appreciate your work and hope you will continue to share your research with us.

Interesting to see that 2004 Power Dissipation Index (PDI) is almost similar to 2005 PDI. 2005 was more spread out than 2004. 2004 had more long lived hurricanes as there were more Cape Verde Hurricanes than in 2005. 2005 hurricanes formed in the Caribbean, Gulf of Mexico, or Northeast Atlantic. Most formed closer to land than in 2004.

[weathaguyry]

I'm bringing back this thread. If most indicators point to positive for the 2017 Hurricane Season, maybe it will be a good indicator to see if the active era has ended or not.

[TheStormExpert]

If these articles are any indication then it very well may be over or coming close to an end soon.

http://www.wptv.com/weather/hurricane/study-invisible-protective-barrier-protected-florida-during-active-hurricane-seasons

http://nytimes.com/2017/01/04/science/hurricanes-us.html?_r=1&referer=

[GeneratorPower]

This whole active era thing doesn't convince me of anything. Obviously there are seasonal and decadal changes to the number of storms and their intensities and locations. But how does this justify the idea of active eras? There simply hasn't been enough years of solid data to make meaningful assumptions about such long term patterns. Satellite data only since 1960s! Other evidences of storms come only from their impacts, primarily when a storm happened to hit a population center in say, the 1800s. After we have 200-300 years of satellite data we can then make meaningful observations about patterns like this. To me, it is a supreme example of the hubris of scientists to assume we have enough data to project this type of thing.

[Yellow Evan]

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.

[Hammy]

If we head into another El Nino (or even abortive one similar to 2014, which still had an impact) of have further issues with the thermohaline circulation similar to 2013, then we still won't be able to tell for another year or two.