Is the Atlantic hurricane season getting longer?

By: Dr. Jeff Masters , 1:35 PM GMT on November 11, 2010

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It seems like there have been an unusual number of early and late season tropical storms and hurricanes in the Atlantic in recent years. In 2008, we had four named storms in July, and the second most powerful November hurricane on record. Both 2007 and 2005 had rare December storms, and 2003 featured Tropical Storm Anna, the first April tropical storm ever recorded. This year, Hurricane Tomas made 2010 the fourth straight year with a November hurricane, something that has never occurred in the Atlantic since accurate records began in 1851. The latest runs of the GFS and NOGAPS models are suggesting the possibility that we will have Tropical Storm Virginie in the Caribbean between Colombia and Nicaragua a week from now. Is hurricane season getting longer? Dr. Jim Kossin of the University of Wisconsin published a 2008 paper in Geophysical Research Letters, "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high".


Figure 1. Observed sea surface temperature (SST) trends during the official North Atlantic hurricane season (June-November) for the period 1950-2007. Units are °C per century. The dashed rectangle denotes the tropical storm formation region south of 30° North latitude and east of 75° West longitude. Data are from the NOAA Extended Reconstructed Sea Surface Temperature V3 product [Smith et al., 2008]. Image credit: Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Methods
Dr. Kossin utilized the "best track" database of Atlantic tropical cyclone activity going back to 1851. However, since lack of satellite and aircraft reconnaissance data before 1950 makes the early part of this record suspect, he limited his analysis to the period from 1950 onward. The era of best data--the satellite era beginning in 1980--was also looked at separately, to ensure the highest possible data quality. The area studied was only a portion of the Atlantic--the tropical storm formation region south of 30° North latitude and east of 75° West longitude. This region has shown considerable warming of the Sea Surface Temperatures (SSTs) since 1950, in excess of 1°F (0.6°C) (Figure 1). A statistical method called "quantile regression" was employed. The method looked at how certain thresholds that mark the beginning and end of hurricane season have changed over the years. For example, the date where 5% of all tropical storms form earlier than that date, was called the 0.05 quantile, and the date where 5% of all tropical storms form later than that date, was called the 0.95 quantile. Kossin was able to show that the date of the 0.05 quantile got steadily earlier and the date of the 0.95 quantile steadily got later since 1950. Hurricane season for both the period 1950-present and 1980-present got longer by 5 to 10 days per decade.


Figure 2. Trends in tropical storm formation dates, in the region south of 30° North latitude and east of 75° West longitude, at the 0.05.0.95 quantiles. Trends are based on the periods (left) 1950-2007, and (right) 1980-2007. The dates (month/year) associated with the 0.05, 0.25, 0.50, 0.75, and 0.95 quantiles for each period are shown on the top axis (these threshold dates are based on the full sample for each period). Shading denotes the 90% confidence interval. Image credit: Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Relationship with Sea Surface Temperature
The broadening of the Atlantic hurricane season found was strongly dependent upon Sea Surface Temperatures. Both the onset and end of hurricane season shifted by 20 days per degree C of warming of the SST. With global warming projected to increase tropical Atlantic SSTs 1-2°C by the end of the century, can we then expect a 40-80 day increase in the length of hurricane season? Dr. Kossin doesn't explore this possibility, and doesn't blame the observed increase in the length of the season on human-caused global warming of the oceans. There is reason to believe that future warming of the Atlantic SSTs won't necessarily broaden the area over which tropical storms will form, though. Papers by Henderson-Sellers et al. (1998) and Knutson et al. (2008) theorize that as SSTs warm, the lowest temperature at which tropical storms can form will also increase. The current minimum temperature of 26.5°C (80°F) may increase to 28.5°C for a 2°C warming of Atlantic SSTs. Johnson and Xie (2010) have found observational evidence that the lowest temperature at which tropical storms can form has indeed been increasing at about 0.1°C per decade in the Atlantic, in line with climate model predictions.

References
Henderson-Sellers, A., et al., 1998, "Tropical Cyclones and Global Climate Change: A Post-IPCC Assessment", Bull. Am. Meteorol. Soc. 79, 19–38.

Johnson, N.C., and S.P. Xie, 2010, "Changes in the sea surface temperature threshold for tropical convection", Nature Geoscience doi:10.1038/ngeo1008

Knutson, T.R., J.J. Sirutis, S.T. Garner, G.A. Vecchi, and I.M. Held, 2008, Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", Nature Geoscience 1, 359 - 364 (2008), doi:10.1038/ngeo202

Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Jeff Masters

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Member Since: July 12, 2007 Posts: 0 Comments: 6032
Quoting Orcasystems:


All right...stop that... between you and KOG, your starting to peeve me...

I am NOT putting my Golf clubs away.. its not getting cold..and its not going to snow... so stop it.


I don't see the problem! :)

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Quoting Bordonaro:
FYI...The GFS has a convention of Siberian High pressure areas dumping a gazillion tons of Arctic air into Canada dumping into the Northern CONUS by 11-20-10....

Here is comes the dreaded "Polar Vortex"!!!!!!!
Link


All right...stop that... between you and KOG, your starting to peeve me...

I am NOT putting my Golf clubs away.. its not getting cold..and its not going to snow... so stop it.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Chicklit:
I was wondering about volcanic activity and solar flares. Keeper must remember that humongous flare on the lower left quadrant of an image he posted about a week or so ago.
Anyway, pleasant evening, folks.
goodnight!
that was this area chicklit

Member Since: July 15, 2006 Posts: 171 Comments: 53787
FYI...The GFS has a convention of Siberian High pressure areas dumping a gazillion tons of Arctic air into Canada dumping into the Northern CONUS by 11-20-10....

Here is comes the dreaded "Polar Vortex"!!!!!!!
Link
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I was wondering about volcanic activity and solar flares. Keeper must remember that humongous flare on the lower left quadrant of an image he posted about a week or so ago.
Anyway, pleasant evening, folks.
goodnight!
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Member Since: Posts: Comments:
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THREAT LEVEL MEDIUM 7 C CLASS FLARES IN 48 HRS
Member Since: July 15, 2006 Posts: 171 Comments: 53787
GFS persists at the format ion of Tropical Storm Virginie.


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Quoting Grothar:


A little down today. Always am on these days, but GeoffWPB always has a way of getting me to chuckle on the blog. How are doing, taking over the late shift???


I tear up on this day as well.

I don't know about taking over. I'm happy to interact with the fine folk here.
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Quoting VAbeachhurricanes:


The guys who save our asses with air support on call? :p

My father was radio operator on B56 in WWII; my son is a linguist in the Army who served two tours in Iraq and is now in Seoul.
Veterans are the ones who make it home.
Memorial Day is for the ones who don't.
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Quoting Orcasystems:


The only part I took offence to was the highlighted "non-combat" part.
Let me tell you.. the pointy end doesn't go very far without those "non-combat" types... nor do they have the foggiest idea how to get there.


yeah i know, Neo I apologize, Im very thankful for your service to our troops. Im not having a great day I did not mean to insult you. We disagree on a lot, but by no means do I have the right to insult you. Im sorry. heck maybe you even supplied my cousins air support for his extraction.
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Poor Amarillo, Texas!!!!

9:53 pm
Thunderstorm Heavy Small Hail/Snow Pellets Rain Fog/Mist 47°F

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Quoting VAbeachhurricanes:


No im not old enough to have, but my dad has for 25 years, and my grandpa, and now my cousins have. I will too, once I can. I remember when talking about haiti, how it was "unsensitive" of me to talk about them with a hurricane bearing down on them, so how is it not "unsensitive" to talk about it on veterans day? Just saying, sorry if I came off in the wrong light, seeing what my cousin has gone through, just a little sensitive, again I apologize.


The only part I took offence to was the highlighted "non-combat" part.
Let me tell you.. the pointy end doesn't go very far without those "non-combat" types... nor do they have the foggiest idea how to get there.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting VAbeachhurricanes:


sorry but seeing my cousin with his arm blown off, leaves me a little sensitive to the whole thing...


A lot of us have seen and experienced a lot from war. That's the way it is. The posted article was GOOD, but you use it to take a jab at someone. Then try to use your cousin as an excuse. A non-combat veteran posts a good article about those who have suffered as a result of their service.

Cheap shot!
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Quoting Chicklit:

This is not a good day to tell you what the Army says about Air Force lol.


The guys who save our asses with air support on call? :p
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More record rainfall: 19.3" of rain fell in western Sri Lanka today, breaking the 1992 record of 17.3". Around 36,000 are homeless from the subsequent flooding. Link
Member Since: November 8, 2009 Posts: 4 Comments: 13526
Quoting Chicklit:

This is not a good day to tell you what the Army says about Air Force lol.


Army = Mud Monkey = Pongo = A hairy little creature that digs holes in the ground for no apparent reason :)

Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Orcasystems:


I would be willing to bet, your cousin would support that article to the word.. I could be wrong, but I highly doubt it.

Your remark to IC was totally uncalled for... have you "been there done that"?


No im not old enough to have, but my dad has for 25 years, and my grandpa, and now my cousins have. I will too, once I can. I remember when talking about haiti, how it was "unsensitive" of me to talk about them with a hurricane bearing down on them, so how is it not "unsensitive" to talk about it on veterans day? Just saying, sorry if I came off in the wrong light, seeing what my cousin has gone through, just a little sensitive, again I apologize.
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Quoting PSLFLCaneVet:



We were trying to spare you, Old One. If the posts had happened as quickly as "in season", it would have gone unnoticed. lol

How are you?


A little down today. Always am on these days, but GeoffWPB always has a way of getting me to chuckle on the blog. How are doing, taking over the late shift???
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Quoting KEEPEROFTHEGATE:
if that dipiction comes to pass looks like quite the blast for you and first snows for me we need a few more days on this one hopefully it will change and zone out


I hope its wrong.. still taking pine needles and leaves out of the Koi pond :( ....and its getting freakin cold and wet.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Neapolitan:
One of the best articles I've read regarding today's celebratory holiday.

Bumper-Sticker Patriotism Is No Way to Honor Our Veterans

And before anyone jumps on me for my "typical liberal stance", you should know I am a non-combat veteran of the USAF. ;-)

This is not a good day to tell you what Army says about Air Force lol.

I was wondering today if warming earth would cause more volanic activity. As nature has a way of balancing also learned that volcanoes emit carbon dioxide cools the atmosphere.

...the amount of sulfur dioxide combined with the location of Merapi near the equator could effect global climate, but at this point, it is impossible to know. -- Erik Klemetti

Eruption at Mount Merapi, Indonesia concentrations of sulfur dioxide on November 4%u20138, 2010, as observed by the Ozone Monitoring Instrument (OMI) on NASA%u2019s Aura spacecraft.
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Quoting VAbeachhurricanes:


sorry but seeing my cousin with his arm blown off, leaves me a little sensitive to the whole thing...


I would be willing to bet, your cousin would support that article to the word.. I could be wrong, but I highly doubt it.

Your remark to IC was totally uncalled for... have you "been there done that"?
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Orcasystems:


My aren't you a little ray of sunshine....
if that dipiction comes to pass looks like quite the blast for you and first snows for me we need a few more days on this one hopefully it will change and zone out
Member Since: July 15, 2006 Posts: 171 Comments: 53787
Quoting Grothar:


Twit! Just saw it! LOL



We were trying to spare you, Old One. If the posts had happened as quickly as "in season", it would have gone unnoticed. lol

How are you?
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Quoting Orcasystems:


I have to admit, thats one of the best little articles I have read in a longtime. BZ

Your reply to the remark, leaves a bit to be desired.


sorry but seeing my cousin with his arm blown off, leaves me a little sensitive to the whole thing...
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Quoting KEEPEROFTHEGATE:
so big fish are ya lookin at post 336 you better have them lights finish soon ya got a little time left


My aren't you a little ray of sunshine....
Member Since: October 1, 2007 Posts: 81 Comments: 26511
so big fish are ya lookin at post 336 you better have them lights outside finished soon ya got a little time left
Member Since: July 15, 2006 Posts: 171 Comments: 53787
Quoting VAbeachhurricanes:


exactly so you know nothing what it is like...


I have to admit, thats one of the best little articles I have read in a longtime. BZ

Your reply to the remark, leaves a bit to be desired.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting VAbeachhurricanes:


exactly so you know nothing what it is like...


What's your point?
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Quoting VAbeachhurricanes:


exactly so you know nothing what it is like...

Really? I usually pay no attention to you--ignorant comments like the one above are why--but I have to ask: just how do you know that I don't know what "it" is like? How do you know what I've gone through? How do you know what my grandparents, or my father, or my uncles, or my brothers, or my cousins, or any of ten thousand other ancestors and close friends of mine have seen, and done, and where and how they served?

Here, allow me to repeat the link for your benefit: Bumper-Sticker Patriotism Is No Way to Honor Our Veterans. Please read it (if you can); you may find it interesting. ;-)
Member Since: November 8, 2009 Posts: 4 Comments: 13526
Member Since: July 15, 2006 Posts: 171 Comments: 53787
Quoting Bordonaro:
Long Range 384 HRS 11-27-2010..GFS 10M wind/surface temps..One heckuva cold blast..
it will be the great lakes first widespread snows then the cold
Member Since: July 15, 2006 Posts: 171 Comments: 53787
Quoting GeoffreyWPB:
Happy Veterans Day to all of our brave and dedicated service men and woman. I celebrated with my good friend Grothar down in Ft. Lauderdale....Here is a brief clip:



Twit! Just saw it! LOL
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Quoting washingtonian115:
Mr.Winter can stay in Canada somewhere.....I certainly don't want him here cuasing trouble like he did this year,and last.



If he comes...its was because he was invited :)


668. PensacolaDoug 1:54 PM GMT on October 08, 2010 Hide this comment.

Quoting Orcasystems:


KOG, PDoug was unhappy with your attempt at snow last year.



Yes I was. So this year I'm putting in my order early for a repeat of Feb 1899!!
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting washingtonian115:
Mr.Winter can stay in Canada somewhere.....I certainly don't want him here cuasing trouble like he did this year,and last.


+100
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Quoting washingtonian115:
Mr.Winter can stay in Canada somewhere.....I certainly don't want him here cuasing trouble like he did this year,and last.
winter is coming in a big way

Member Since: July 15, 2006 Posts: 171 Comments: 53787
Quoting Quadrantid:


A beautiful image, but seeing light pollution like that makes me weep. As an astronomer, I'm fortunate enough to have been out under truly dark skies - and so I've seen the sights that are lost to pretty much everyone in the developed world thanks to the curse of poorly designed lighting :(

Simply fitting internal reflectors in street lights would ensure that the great majority of their light would head down, rather than up (most modern streetlights waste something like 30% of their energy illuminating the night sky). We'd save energy, better illuminate our streets, and make a start returning to properly dark skies.

The problem is exacerbated by all these people who have crazy 500W garden "anti-burglar" lights/security lights. They're insane. All they do is throw so much light that you're dazzled when you look out, and cast shadows so dark it's trivial for a mugger/burglar to hide in perfect safety while you, the victim, is perfectly lit approaching them.

Sorry -- it's a pet peeve of mine -- so few people these days get to see the splendour of the milky way, or see the zodiacal light, the Andromeda galaxy, and the general beauty of a properly dark sky -- and yet the one type of pollution we still do nothing to diminish or legislate against is light pollution. If my neighbour has their music on too loud at 3am, so I can't sleep, I have legal recourse. If they have a security light so bright I can't sleep, there's typically nothing I can do.

That all said, light pollution does make the surface of the planet look pretty stunning from the air -- night landings in big cities are always spectacular -- but it's always depressing thinking just how much energy is being wasted, thrown in the sky to do nothing but fill it with glow and glare, hiding what we really should be able to see...


But if we do as you suggest how will the aliens find us? ;)

note: a plus of a hurricane - no lights = great sky viewing
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Quoting geepy86:

Here comes Mr. winter.
Mr.Winter can stay in Canada somewhere.....I certainly don't want him here cuasing trouble like he did this year,and last.
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Flooding in the US Virgin Islands on the Island of St. Croix

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Flooding in the US Virgin Islands on the Island of St. Croix

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Flooding in the US Virgin Islands on the Island of St. Croix

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Flooding in the US Virgin Islands on the Island of St. Croix

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Quoting Bordonaro:

The National Weather Service in Ft Worth, TX mentioned this at 9:37PM CST on 11-10-10 in the Area Forecast Discussion.

Whenever the mention these two words "Polar Vortex" in a forecast discussion, it is going to get very freaking cold!!!

Here comes Mr. winter.
Member Since: August 19, 2008 Posts: 0 Comments: 1701
Flooding in the US Virgin Islands on the Island of St. Croix


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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.