Is the Atlantic hurricane season getting longer?

By: Dr. Jeff Masters , 6:34 PM GMT on December 16, 2008

Share this Blog
3
+

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. 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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 107 - 57

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8Blog Index

In his fascinating book Carbon Detox, George Marshall argues that people are not persuaded by information. Our views are formed by the views of the people with whom we mix. Of the narratives that might penetrate these circles, we are more likely to listen to those that offer us some reward. A story that tells us that the world is cooking and that we'll have to make sacrifices for the sake of future generations is less likely to be accepted than the more rewarding idea that climate change is a conspiracy hatched by scheming governments and venal scientists, and that strong, independent-minded people should unite to defend their freedoms.

He proposes that instead of arguing for sacrifice, environmentalists should show where the rewards might lie: that understanding what the science is saying and planning accordingly is the smart thing to do, which will protect your interests more effectively than flinging abuse at scientists. We should emphasise the old-fashioned virtues of uniting in the face of a crisis, of resourcefulness and community action. Projects like the transition towns network and proposals for a green new deal tell a story which people are more willing to hear.

Marshall is right: we have to change the way we talk about this issue.

I am in agreement w/Marshall MichaelSTL --

remember though you get more cooperation w/honey then venom

our present methods of energy, farming and lack of birth control hurt the planet..... GW or not. why do the humans insists on using products and methods that hurt the earth in any way. We need not to add to the earth's stress factor and we need to change our ways & think. "you dont "sh--" where you eat.
Member Since: July 18, 2007 Posts: 30 Comments: 26536
104 rob
He reads them all. Anyone that insecure would have to.
Member Since: Posts: Comments:
Quoting from Michael's posts...

We all create our own reality, and shut out the voices we do not want to hear

Yeah, that sounds kinda familiar...somewhat like the infamous ignore list.

Good-bye, MixedUpSod; #61!

Add to that the name-calling. And your attacks on entire groups...Christians,(actually you used the term creationist, which includes many more people than Christianity alone), Conservatives, and esentially any other group who's way of thinking does not mesh with your own.

Is it any wonder many of us just scroll through your posts? I know you won't read this because I am on your list "for Agreeing with a troll" (your exact words) I never said a thing bad about you...never even publically disagreed with you. Still I got on the list.

Just seems strange to me that you would post an article calling for a more open and productive dialog on the topic.
Member Since: Posts: Comments:
Quoting Buhdog:
STL,

Although many will never buy into what you post...thank you for doing a good job of showing actual data and reports to back it up.
Please don't encourage him. He has 61 people on his "iggie" list here. Not fair to have to endure these rants without equal time. He has his own blog for that.
Member Since: Posts: Comments:
STL,

Although many will never buy into what you post...thank you for doing a good job of showing actual data and reports to back it up.
Member Since: Posts: Comments:
Quoting presslord:
Attention all hands!!!!


I just met Stormjunkie, Jr.

....quite a handsome young man....doesn't look a thing like his father....
Yo press...
Good news. Skips a generation, huh???
Member Since: Posts: Comments:
95 P451
Sophism exists in Science as well as Politics.
That's why we educate ourselves...LOL
Member Since: Posts: Comments:
Attention all hands!!!!


I just met Stormjunkie, Jr.

....quite a handsome young man....doesn't look a thing like his father....
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Clearly a closed surface low:

Link

Member Since: September 9, 2008 Posts: 6 Comments: 3414
I just updated my blog if anyone would like to review.....
Merry Christmas everyone!
TampaSpins Weather Blog Link
Member Since: September 2, 2007 Posts: 179 Comments: 20448
'Death map' shows heat a big hazard to Americans 17 Dec 2008 00:00:17 GMT
Source: Reuters
By Maggie Fox, Health and Science Editor

WASHINGTON, Dec 16 (Reuters) - Heat is more likely to kill an American than an earthquake, and thunderstorms kill more people than hurricanes do, according to a U.S. "death map" published on Tuesday.

Researchers who compiled the county-by-county look at what natural disasters kill Americans said they hope their study will help emergency preparedness officials plan better.

Heat and drought caused 19.6 percent of total deaths from natural hazards, with summer thunderstorms causing 18.8 percent and winter weather causing 18.1 percent, the team at the University of South Carolina found.

Earthquakes, wildfires and hurricanes combined were responsible for fewer than 5 percent of all hazard deaths.

Writing in BioMed Central's International Journal of Health Geographics, they said they hoped to dispel some myths about what the biggest threats to life and limb are.

"According to our results, the answer is heat," Susan Cutter and Kevin Borden of the University of South Carolina wrote in their report, which gathered data from 1970 to 2004.

"I think what most people would think, if you say what is the major cause of death and destruction, they would say hurricanes and earthquakes and flooding," Cutter said in a telephone interview. "They wouldn't say heat."

"What is noteworthy here is that over time, highly destructive, highly publicized, often-catastrophic singular events such as hurricanes and earthquakes are responsible for relatively few deaths when compared to the more frequent, less catastrophic such as heat waves and severe weather," they wrote.

The most dangerous places to live are much of the South, because of the heat risk, the hurricane coasts and the Great Plains states with their severe weather, Cutter said.

The south-central United States is also a dangerous area, with floods and tornadoes.

California is relatively safe, they found.

"It illustrates the impact of better building codes in seismically prone areas because the fatalities in earthquakes have gone down from 1900 because things don't collapse on people any more," Cutter said.
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting MichaelSTL:


Just gibberish posted by some idiot... probably funded by Big Oil (indeed; check this out for info on the so-called scientists who say global warming isn't happening).


Isn't it amazing that every single "skeptic" as you like to call them, is funded by "Big Oil"? It's easy to dismiss something and say that it's automatically funded by some imaginary group, such as "Big Oil," rather than do the research and find out that it's from normal, every day climate scientists who just don't buy in to the load of garbage that media outlets like to report because it makes for some exciting headlines.

What's even more ridiculous is that you follow that up with a review on those climate scientists by referring us to a report from "The Daily Green." Hmm...that's a pretty objective source isn't it? I wonder where they get their funding from? Is there a "Big Solar" or "Big Green" out there that I can complain about?

Please save your ridiculous comments about "Big Oil" and how it funds everything with a view contrary to yours. I'm sure your Al Gore-led support group would be glad to hear them.
Member Since: Posts: Comments:
Not too much warming in Great Falls for the last 100 years...

Link
Member Since: Posts: Comments:
Cyclone fears prompt offshore rig evacuation
Wednesday December 17, 2008 - 14:40 EDT

Oil and gas exploration workers have been evacuated from offshore rigs in preparation for a possible cyclone off the Western Australian coast.

The Bureau of Meteorology is monitoring a weak low between Timor and the Tiwi Islands, off the north Australian coastline.

The bureau says it could develop into a cyclone within the next few days.

Port authorities in Broome say four companies have begun moving workers from offshore rigs.

- ABC
Member Since: Posts: Comments:
Quoting HadesGodWyvern:


BOM Darwin is showing a slight possibility of Tropical Cyclone Billy just before landfall
Will it be Tropical Cyclone Billy or Tropical Cyclone Anika ???
Member Since: Posts: Comments:
Quoting HadesGodWyvern:


BOM Darwin is showing a slight possibility of Tropical Cyclone Billy just before landfall

Updated
Member Since: Posts: Comments:
Quoting HadesGodWyvern:
Darwin Tropical Cyclone Warning Center
Tropical Cyclone Advice Number ONE
TROPICAL LOW (02U)
4:00 PM Austialia CST December 17 2008
=====================================

At 12:30 PM Australian CST, a Tropical Low [1004 hPa] located at 12.5S 127.0E, or 205 kilometres north northeast of Kalumburu and 420 kilometres west of Darwin has 10 minute sustained winds of 25-30 knots with gusts up to 45 knots. The low is reported as moving southwest at 7 knots towards Kimberley coast.

There is the possibility of a tropical cyclone developing close to the north Kimberley coast on Friday. GALES are not expected in coastal areas within the next 24 hours, however gales could develop later.

Tropical Cyclone Watch
=========================
A Cyclone WATCH has been declared for a developing tropical low for coastal and island communities from Cockatoo Island in WA to the Western Australia/Northern Territory Border.

TROPICAL CYCLONE WATCH

TROPICAL CYCLONE ADVICE NUMBER 2
Issued by the BUREAU OF METEOROLOGY, DARWIN
at 11:10 pm Australian CST [10:40 pm WDT] Wednesday 17 December 2008

A Cyclone WATCH continues for a developing tropical low for coastal and island
communities from Cockatoo Island to WA/NT Border.

At 9:30 pm Australian CST [9:00 pm WDT] a Tropical Low was estimated to be 190 kilometres
north northeast of Kalumburu and 370 kilometres west of Darwin, moving slowly
south towards the Kimberley coast.

There is the possibility of a tropical cyclone developing close to the north
Kimberley coast on Friday. GALES are not expected in coastal areas within the
next 24 hours, however gales could develop later.

Details of Tropical Low at 9:30 pm CST [9:00 pm WDT]:
.Centre located near...... 12.8 degrees South 127.5 degrees East
.Location accuracy........ within 110 kilometres
.Recent movement.......... towards the south at 2 kilometres per hour
.Wind gusts near centre... 85 kilometres per hour
.Severity category........ below cyclone intensity
.Central pressure......... 1004 hectoPascals

The next advice will be issued by 5:00 am CST Thursday 18 December [4:30 am WDT
Thursday 18 December].

DARWIN Tropical Cyclone Warning Centre

Member Since: Posts: Comments:
Quoting hurristat:


Why is it that the threshold rises?
The threshold extends, not rises according to Dr Gossin. And he admitts the uncertainty of the relationship is high. To wit: warmer water allows a storm to form in cooler air temps.
Excluding the Paciffic and other oceans "may" lead to conjecture by opponents that either the SST's are not rising universely or either his theory is hogwash.
He should have completed his homework.
Member Since: Posts: Comments:
83. Skyepony (Mod)
Here's a few 2008 highlights from NOAA..

Arctic sea ice extent in 2008 reached its second lowest melt season extent on record in September. The minimum of 1.74 million square miles (4.52 million square kilometers) reached on September 12 was 0.86 million square miles (2.24 million square kilometers) below the 1979-2000 average minimum extent.


The 2008 Atlantic hurricane season was the third most costly on record in current dollars, after 2005 and 2004, and the fourth most active year since 1944. This was the first season with a major hurricane (Category 3 or above) each month from July through November. With the exception of the South Indian Ocean, all other tropical cyclone regions recorded near to below-average activity during 2008. Globally, there were 89 named tropical cyclones, with 41 reaching the equivalent of hurricane strength (74 mph), and 20 achieving the equivalent of major hurricane status (111 mph or greater) based on the Saffir-Simpson scale.


The United States recorded a preliminary total of just under 1,700 tornadoes from January - November. This ranks 2008 second behind 2004 for the most tornadoes in a year, since reliable records began in 1953.


Torrential rains caused widespread flooding in parts of Vietnam, Ethiopia, northern Venezuela, Brazil, Panama, and the northern Philippines during November. Several million people were displaced and nearly 200 fatalities were reported. Monsoonal rainfall was much above average over many regions in 2008. Mumbai, India, recorded its greatest June rainfall in seven years, while Hanoi, Vietnam, observed its greatest October rains since 1984
Member Since: August 10, 2005 Posts: 192 Comments: 38654
82. Skyepony (Mod)
More November numbers are out.. It was the 6th warmest November for the Northern Hemisphere since 1880. Link for the ncdc climate anylisis isn't working for me.. NOAA does have their monthly write up out.. 4th warmest globally.
Member Since: August 10, 2005 Posts: 192 Comments: 38654
Goodmoring all. going to be 80 here today. wow, where did my winter go. I know we don't have alot of snow here in Elkton but maybee some frost would be nice!
Member Since: Posts: Comments:
Good Morning from N.C.
53F and forecast to be 70F today
Must be GW!!!!!!
Cloudy all day
Member Since: Posts: Comments:
It occurred to me we might not have enough data. Just Fifty years ago we missed or looked over lots of storms even full-blown hurricanes until re-analysis and 100 years ago we missed out on cat 2 and 3s and didn't find them at re-analysis so I think a few late season and early season storms weren't recorded
Member Since: Posts: Comments:
Is our not-Rene in the Mid-Atlantic now Because i think that low looks like it has potential
Member Since: Posts: Comments:
Quoting CaicosRetiredSailor:
SYNOPSIS FOR THE SW N ATLC INCLUDING THE BAHAMAS
430 PM EST TUE DEC 16 2008
.SYNOPSIS...STRONG HIGH PRESSURE N OF THE AREA TONIGHT WILL
GRADUALLY WEAKEN THROUGH THU NIGHT. NON-TROPICAL LOW...1010
MB...NEAR 26N56W
WILL TRACK SW TO WSW TO 25N62W WED AFTERNOON
AND OPEN UP INTO A TROUGH LATE THU OVER PUERTO RICO AND
HISPANIOLA.
Link


QuikScat showing circulation near 26N x 57W
Link


STS Rene?!
Member Since: Posts: Comments:


BOM Darwin is showing a slight possibility of Tropical Cyclone Billy just before landfall
Member Since: May 24, 2006 Posts: 51 Comments: 46151
Darwin Tropical Cyclone Warning Center
Tropical Cyclone Advice Number ONE
TROPICAL LOW (02U)
4:00 PM Austialia CST December 17 2008
=====================================

At 12:30 PM Australian CST, a Tropical Low [1004 hPa] located at 12.5S 127.0E, or 205 kilometres north northeast of Kalumburu and 420 kilometres west of Darwin has 10 minute sustained winds of 25-30 knots with gusts up to 45 knots. The low is reported as moving southwest at 7 knots towards Kimberley coast.

There is the possibility of a tropical cyclone developing close to the north Kimberley coast on Friday. GALES are not expected in coastal areas within the next 24 hours, however gales could develop later.

Tropical Cyclone Watch
=========================
A Cyclone WATCH has been declared for a developing tropical low for coastal and island communities from Cockatoo Island in WA to the Western Australia/Northern Territory Border.
Member Since: May 24, 2006 Posts: 51 Comments: 46151
Bureau of Meteorology in Australia
TROPICAL CYCLONE OUTLOOK WESTERN AUSTRALIA 110E-125E
Issued at 2:00pm WDT on Wednesday the 17th of December 2008
===========================================
A developing Tropical Low [1002 hPa] is situated north of the Kimberley in the Timor Sea. At midday it was near 12.5S 127.0E, about 220 km north-northeast of Kalumburu and moving towards the south at about 8 km/h. The low is expected to move slowly towards the southwest during the next few days, towards the north Kimberley coast.

Tropical Cyclone Development Potential
=====================================
Thursday: Low
Friday: High
Saturday: High
Member Since: May 24, 2006 Posts: 51 Comments: 46151
Thanks Geoffrey -

I could use some xmas tunes...but so reflective and worried for people. And our family too.

Member Since: Posts: Comments:
Quoting theshepherd:
Why, to which statement?


Why is it that the threshold rises?
Member Since: Posts: Comments:
Your Christmas song for the night...

Member Since: Posts: Comments:
please send a hurricane my way this week...what a crap day.

and yes, i'm wishcasting.
Member Since: Posts: Comments:
Quoting hurristat:
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 continue to broaden the length of hurricane season at the rate Kossin suggests has occurred. 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. Furthermore, Kossin's results apply only to the Atlantic Ocean, and it is uncertain whether or not hurricane season is changing in length in other ocean basins. -Jeff Masters


Why is that?
Why, to which statement?
Member Since: Posts: Comments:
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 continue to broaden the length of hurricane season at the rate Kossin suggests has occurred. 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. Furthermore, Kossin's results apply only to the Atlantic Ocean, and it is uncertain whether or not hurricane season is changing in length in other ocean basins. -Jeff Masters


Why is that?
Member Since: Posts: Comments:
Quoting TampaSpin:
I have seen Highs before but, wow...lol



ROFLMAO!!! headache time!!!
Member Since: Posts: Comments:
Quoting TampaSpin:
I have seen Highs before but, wow...lol



How current is this image? This is great for wind surfing!
Member Since: Posts: Comments:
SYNOPSIS FOR THE SW N ATLC INCLUDING THE BAHAMAS
430 PM EST TUE DEC 16 2008
.SYNOPSIS...STRONG HIGH PRESSURE N OF THE AREA TONIGHT WILL
GRADUALLY WEAKEN THROUGH THU NIGHT. NON-TROPICAL LOW...1010
MB...NEAR 26N56W
WILL TRACK SW TO WSW TO 25N62W WED AFTERNOON
AND OPEN UP INTO A TROUGH LATE THU OVER PUERTO RICO AND
HISPANIOLA.
Link


QuikScat showing circulation near 26N x 57W
Link
Member Since: Posts: Comments:
Wondering if this could become the 1st Cyclone of Aussie 08/09 season.



Cheers AussieStorm
Member Since: Posts: Comments:
Here's your (low) the models have been harping on for a few days now...

Member Since: Posts: Comments:
Quoting TampaSpin:
I have seen Highs before but, wow...lol

Wow! Hope all is well with you Tampa
Member Since: Posts: Comments:
Member Since: May 24, 2006 Posts: 51 Comments: 46151

Viewing: 107 - 57

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8Blog Index

Top of Page

About

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