Global warming and hurricanes part 2: An increase in late-season activity?

By: Dr. Jeff Masters , 6:33 PM GMT on January 09, 2006

Good Tuesday to everyone! This week we need to watch a large extratropical low-pressure system sliding down the coast of Africa towards the Cape Verde Islands. This low is similar to the storms that spawned Delta, Epsilon, and Zeta, and has the potential to slowly gain tropical characteristics and become Tropical Storm Alberto later this week. However, it appears that wind shear levels will probably be too high and the water too cool for a new tropical storm to form. The chances of a tropical storm forming this week are probably around 20%.

Has there been an increase in late-season tropical storm activity?
Hurricane experts agree that global warming has not led to an increase in the number of tropical cyclones occurring world-wide, and are currently debating whether or not global warming has affected tropical cyclone intensity (more on this later in January, I've been pulling together a lot of material). Is global warming possibly affecting the length of hurricane season, as well? It seems that an inordinate number of late-season and off-season tropical storms have been forming in the Atlantic the past few years. For example, two December storms formed in 2003, which also had the first-ever April storm, Tropical Storm Ana. Cuba's worst hurricane ever, Hurricane Michelle, hit in November 2001, and the Atlantic's second deadliest hurricane of all time, Hurricane Mitch, lasted into November 1998. Add to this 2005's Greek cousins, Gamma, Delta, Epsilon, and Zeta, which all occurred in November and December. To see if hurricane season is indeed lasting longer, I plotted up the number of days a named storm existed each year from November through April (Figure 1). The data cut-off is 1944--the beginning of reliable hurricane records in the Atlantic, thanks to regular long-range aircraft reconnaissance missions. According to Dr. Chris Landsea's paper, A Climatology of Intense Atlantic Hurricanes, only a very few short-lived tropical storms that formed far out over the open Atlantic were missed by these aircraft missions or ships plying the shipping lanes between Europe and North America. For example, all of 2005's Greek storms were long-lived enough and sufficiently intense that they would have been detected back in the 1944-1960 time frame. Beginning 1960, weather satellites gave us full coverage of all the ocean areas, and it is unlikely we missed any tropical storms after then. Thus, Figure 1 is likely to be an accurate measure of the late-season tropical storm activity for the Atlantic.

Figure 1.Number of days a named tropical storm was present in the Atlantic for each year during November through April, 1944-2005. The 2.5 named tropical storm days from the March 2004 hurricane in the South Atlantic that hit Brazil--Hurricane Catarina--are not included.

Looking at Figure 1, we see a noticeable increase in the number of late-season named-storm days in the Atlantic in the past decade, roughly coinciding with the upswing in Atlantic intense hurricane activity that began in 1995. This increase in late-season tropical cyclone activity was not observed during the previous warm phase of theAtlantic Multidecadal Oscillation (AMO), the natural cycle that greatly influences hurricane activity in the Atlantic. This previous warm phase of the AMO lasted from 1926-1969. Thus, it seems unlikely that the recent upswing in late-season Atlantic tropical storm activity is due to the AMO. Is global warming to blame, then? Global sea surface temperatures in the tropics have increased by .3 degrees C (.5 degrees F) the past century, so it is reasonable to ask if this increase has lengthened hurricane season.

To answer this question, we look at the November though April number of tropical storm days for the Northern Hemisphere's other ocean basins that have tropical cyclones--the Western Pacific (Figure 2) and the Eastern Pacific (Figure 3). Neither ocean basin shows any increase in the length of their hurricane seasons, so global warming has not caused a Northern Hemisphere-wide increase in the length of hurricane seasons. If global warming is to blame for the recent increase in Atlantic late season and off-season tropical storm activity, it is probably through some as yet not understood mechanism, and not directly due to increased the sea surface temperatures over the Atlantic.

Figure 2. Number of days a named tropical storm was present in the Northern Hemisphere's Western Pacific Ocean for each year during November through April, 1945-2005.

Figure 3. Number of days a named tropical storm was present in the Northern Hemisphere's Eastern Pacific Ocean (off the coast of Mexico) for each year during November through April, 1949-2005

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

Log In 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: 207 - 157

Page: 1 | 2 | 3 | 4 | 5Blog Index

207. Inyo
9:07 AM GMT on January 14, 2006
it was certainly implied in a lot of his posts and i believe in the newer thread it is.

I wouldn't use the political analogy if this completely scientific study that began in the early 1980's, wasn't being hijacked by radical liberal groups throughout the world in hopes of advancing their own political agenda.

It was kind of a waste to post this here, and probably not that appropriate since clearly everyone is jumping on him right now. It's good to hear from the 'other side' of things, but to me (i am liberal in a lot of ways but try to be objective) it really seemed very 'slanted'
Member Since: September 3, 2002 Posts: 42 Comments: 932
206. TampaSteve
12:41 AM GMT on January 14, 2006
Inyo...did chaser actually say those things, or are you just putting words in his mouth???
Member Since: July 8, 2005 Posts: 1 Comments: 97
205. Inyo
12:03 AM GMT on January 14, 2006
man, hurricanechaser's credibility really went out the window when he started spouting these right-wing 'conspiracy' theories. Oh yes, the LIBERALS are trying to destroy our country by requesting a change to renewable resources, therefore the entire scientific community is corrupted, but on the other hand the oil companies and their president are TOTALLY objective as to whether or not THEIR PRODUCT, which makes them money, causes a problem. Anyone who would trust what our government is feeding us now is probably the type who would let a fox guard their chickens, or believe Marlboro's assertion that cigarettes are harmless despite watching several smoking relatives die of lung cancer. Seriously, its really a stretch. You have a lot of good knowledge about climatology, and interesting scientific theories, but your political rant is just silly.

You also seem to be literally angered by these scientific theories, to the point where it seems like you are in denial, or something. A real scientist will use evidence, not bunk politics, to prove a point, and although you do present evidence for natural warming (which i believe IS indeed a cause of much, if not all, of the warming) you don't really present anything debunking the theory that increased carbon dioxide in the atmosphere will warm the climate... something that has been documented in ice cores, etc.

And i am with you completely on one thing:

i believe natural climate variation in the past has been far more extreme, sudden, dramatic, and wide ranging than anything we are looking at now, and these huge natural fluxuations may very well dwarf human-caused global warming. If this is what we are in for... the oil isn't going to make much of a difference and we're in for it either way.
Member Since: September 3, 2002 Posts: 42 Comments: 932
204. SafeInTexas
12:47 AM GMT on January 12, 2006
cyclonebuster, your tunnel idea is probably a good idea for electricity generation, but promoting it as a climate control mechinism is a poor idea.

Fluid mixing, why do you believe the cooler water will stay on the surface. My assumption (without any futher data) is that the cooler water is likely more saline, cold salty water should sink rather quickly. This in itsself may have side effects of a cold water column at the end of the tunnel, slowing down the flow of water through the tunnel reducing its effectiveness.

What will kill the project all together is the political fallout from the environmental effects. Building a 2000 square mile parking lot would cause noticable local, provable environmental effects (see Heat Island). Building a 2000 square mile cold spot in the ocean will cause noticable local, provable environmental effects. Putting (whatever a large amount in tonnes) of CO2 in the air does not cause a local, provable environmental effect, in this case human induced global warming. An ulgy building in an office park will get torn down quickly. Urban spral, there is not a quick or even correct solution for that.

Technology for modifing the weather should follow one important law. The Law of Unintended Consequences.

I could talk about this all day, but I'll stop here for now.
Member Since: September 19, 2005 Posts: 0 Comments: 67
203. Fshhead
9:15 AM GMT on January 11, 2006
At least someone else takin the heat for this one....
hey Chaser..... Now I dont look so bad huh?????/
Member Since: November 19, 2005 Posts: 9 Comments: 9960
201. atmosweather
4:04 AM GMT on January 11, 2006
Hey David :) I will check out your blog now.

Meanwhile, New Delhi, India had their first frost in 70 years. Extremely rare cold air invasion from the Himalayas. I also have been hearing that areas of New York were affected by a minor earthquake last night. If anyone has any more details about that I would appreciate it greatly :)


Member Since: September 24, 2005 Posts: 33 Comments: 9265
200. KatrinaRitaWilmaZeta
3:59 AM GMT on January 11, 2006
atmosweather my blog is update for the frist time in 3 days so come on by
199. atmosweather
3:53 AM GMT on January 11, 2006
Hey Tony, hope you are ok. Go get your well deserved rest after the great weather 101 blog you compiled :)
Member Since: September 24, 2005 Posts: 33 Comments: 9265
198. atmosweather
3:51 AM GMT on January 11, 2006
Hey everyone :)

I have to say that cyclonebuster's idea about the tunnels is ingenious. It would be very very hard to pull off but the principle is awesome. I honestly don't think it will work because it is so hard to regulate something like that, but its not impossible and the concept is fantastic. Very well thought out :)

If anyone hasn't read my updated outlook on the 2006 Atlantic Hurricane Season, you are welcome to leave a comment and your own predictions if you wish.

Hope everyone has a great night.

Member Since: September 24, 2005 Posts: 33 Comments: 9265
197. KatrinaRitaWilmaZeta
3:51 AM GMT on January 11, 2006
hey ProgressivePulse how are you come by my blog it has this been update
196. hurricanechaser
3:50 AM GMT on January 11, 2006
Hey everyone,

I have to get some sleep, but I wanted to post a link to my latest blog entry, which I don't normally do. However, I posted a new blog with the NHC reply from the authors of the Hurricane Katrina report.


195. mobal
3:49 AM GMT on January 11, 2006
Thank you for your knowlagable analysis.
Member Since: August 3, 2005 Posts: 482 Comments: 5333
193. ProgressivePulse
3:42 AM GMT on January 11, 2006
Howdy KRWZ
Member Since: August 19, 2005 Posts: 5 Comments: 6924
192. KatrinaRitaWilmaZeta
3:39 AM GMT on January 11, 2006
whats up
190. ProgressivePulse
3:36 AM GMT on January 11, 2006
Messing with something so important as the Gulf Stream is disasterous.
Member Since: August 19, 2005 Posts: 5 Comments: 6924
188. ProgressivePulse
3:33 AM GMT on January 11, 2006
Yeah I have to agree on the enviornmental impact. You are talking migration cycles, current and solidity of the water. Seems you would have a bunch of pissed of cold fish.
Member Since: August 19, 2005 Posts: 5 Comments: 6924
186. ProgressivePulse
3:27 AM GMT on January 11, 2006
Why don't you just set up a bunch of turbofans in the sahara desert and pump dust in the air during hurricane season. Seemed to have put quite a damper in this season.
Member Since: August 19, 2005 Posts: 5 Comments: 6924
185. ForecasterColby
3:18 AM GMT on January 11, 2006
A MET's name is Chris LANDSEA?

184. ForecasterColby
3:17 AM GMT on January 11, 2006
I suggest a ban on discussions of NOLA reconstruction - all they lead to is flaming.
183. Skyepony (Mod)
2:55 AM GMT on January 11, 2006
Hey ~ the NOVA science now was good. Better yet on their site they have an audio-read along with lots of graphs (all copyrighted or i'd of posted them~must see stuff).

Here's the synopsis of the couple of Doctor's life work.

There is a corrilation between SST going up and more energy being released by hurricanes. SST have been steadily rising around the world. The total energy being released by hurricanes around the world has remained about the same. The total # of storm days & # of storms for the world have dropped in total recently due to that natural cycle. All areas except the atlantic has seen average or well below average storm # & days, while the Atlantic's storm #'s & storm days have shot up in a near vertical trend since 1995. Over the last 35 years as the total storm days & storm #'s for the world have decreased the # of cat 4 & 5 storms have doubled. All of this is backed up with graphs, data & numbers. The question of~ is the rise in SST due to global warming? left unanswered.

GO HERE & CLICK ON HOTTER OCEANS FIERCER STORMS ~starting tommarrow you can see web cast of the scientist talking about it all. It's the show they're running tonight ~PBS
Member Since: August 10, 2005 Posts: 418 Comments: 43837
181. ProgressivePulse
2:44 AM GMT on January 11, 2006
Now cyclonebuster, you just need to figure out how to get the hurricane to travel over the tunnel and you will be set. Some hotdogs usually get my dog where I want him.
Member Since: August 19, 2005 Posts: 5 Comments: 6924
180. MDI
2:37 AM GMT on January 11, 2006
I like the question mark at the end of the title for this blog. Did anyone else see that?
179. MDI
2:35 AM GMT on January 11, 2006
Hey that was wierd>>

Posted By: cyclonebuster at 9:15 PM GMT on January 10, 2006.
Hey cyclonebusteer,
178. hurricanechaser
1:58 AM GMT on January 11, 2006
To everyone else including Dr. Masters,

I sincerely apologize for taking up so much space taking part in this back and forth jabbing at one another.

I hope everyone has a great night.:)


177. weatherguy03
1:58 AM GMT on January 11, 2006
Easy Tony...I didnt get your mail right away..LOL..I am slow, been doing other stuff...Hope you got my mail..Take care..

Member Since: July 5, 2005 Posts: 593 Comments: 29742
176. hurricanechaser
1:54 AM GMT on January 11, 2006
Hey Bob,

If you got my mail you will see the reason I blocked you is because I wanted the continued name calling to end..then I come in here after sending you that email and see it continues anyway...regardless, I simply hope you will ponder my comments.:)


174. hurricanechaser
1:50 AM GMT on January 11, 2006
Hey Bob,

Sorry...I hope you got it...I forgot I can't copy what I wrote after its gone.:)

173. hurricanechaser
1:48 AM GMT on January 11, 2006
Hey Bob,

Here's a copy of my response to your post...I'm not a coward...LOL..thats something you would never say to me in person.:)

172. Skyepony (Mod)
1:39 AM GMT on January 11, 2006
There's a show on PBS about this right now (EST)
Member Since: August 10, 2005 Posts: 418 Comments: 43837
171. weatherguy03
1:38 AM GMT on January 11, 2006
Tony you are a coward!!!..Why are you blocking my e-mails to you!!!...Ha Ha!!..Hey you can post my e-mails to you I dont care..So instead of sending you mail because I didnt want to use up Dr. Masters space I guess I will just say it to your face here then..Sorry Dr. Masters...
Member Since: July 5, 2005 Posts: 593 Comments: 29742
169. hurricanechaser
1:22 AM GMT on January 11, 2006
Hey cyclonebuster,

I will once again say that I commend you greatly for your concept and I am NOT saying that it's IMPOSSIBLE, just for the record.

Only that I personally believe it wouldn't actually work. But, I have been wrong before and will be wrong many more times in the future.

In this case, I hope I am wrong and wish you the best.:)


168. hurricanechaser
1:18 AM GMT on January 11, 2006

I didn't see your last post...sorry about that. I haven't studied this and there are so many unpredictable factors involved that have to be considered such as speed of forward motion, its trajectory, size of the storm, and its surrounding atmospheric conditions, etc.

That's why it's impossible to simplify it that way.

In other words, I am not sure exactly, but it could do so for a relatively short period of time, just not sure how long that would be.

You were saying 40 miles of this 75 degree water...if it was moving at 20 mph...that's only 2 hours over that cooler water and if it was rapidly intensifying when it hit this cooler water, it could weaken very little, especially if it took a trajectory that kept the storm over this water for an even shorter period of time.

We are simply talking about definite answer here.:)

Honstly, I have to go, I've stayed on here about two hours longer than I needed to.:)


166. hurricanechaser
1:09 AM GMT on January 11, 2006


Why is it that you must talk to people on here like we are all Stupid. And that you know it all. This sounds like the blog Pre Katrina that made all others leave Dr.Master's (and this is who it belongs to) and start there own. If you must continue you this can you please bring it to your own."
Thank You,

I have NOT ONCE talked to ANYONE as if they are Stupid nor tried to belittled others like your friend who may very well be you under another screen name.

I wasn't here for Katrina and from what those told me, it was those like Lefty who left this blog, because he had an attitude problem... which wasn't my fault.

I got plenty of emails saying that he was wrong and that they each joined other blogs because of attitudes like those from BOB and Lefty.

Please find where I've ONCE said I was superior to anyone, except when I asked the all knowing Bob, if he wanted to challenge me after he belittled me and insulted my education.

I am not talking to you or anyone specifically most of the time on theses blogs, I'm simply here to share what knowledge I have with others.

I am not here to compete in's obvious others feel threatened and I'm sorry I make you feel stupid.

I have ALWAYS stated I will be WRONG more often than I'm right concerning this inexact science as will everyone else.

As a result, I have very little patience with people who ACTUALLY act superior and say that are ALWAYS RIGHT and their opinions are FACT.

Now, contrast this with the FACT I always say my forecasts are simply MY BEST EDUCATED GUESS...that's called humility but I guess you can't understand that either.

Honestly, your opinion as well as Bobs doesn't matter to me because the ones on here that truly know me would realize you are indeed wrong with your characterization and that's the people I want to communicate with...people who respect others and have humility and don't blame everyone else for their problems.

Simply put, if that's your attitude, then your thoughts are biased and not relevant whatsoever.


164. hurricanechaser
12:54 AM GMT on January 11, 2006
Hey everyone,

I am going to call it a night...this is ridiculous to say the least. LOL

I hope you all have a great night.:)


Please feel free to read my posts on hurricane basics to understand what I already know to be true.:)

It was never a question as to whether a category five could survive over 75 degree temperatures for a sustained period of time or that upwelling wouldn't;t create weakening. Of course, that's true.

You asked if I thought a category five could maintain intensity over 75 degree temperatures and I gave you the possible scenario where it could with it moving quickly over that water temperature for a short period of time.

Obviously, a complete misunderstanding I presume. I hope you now can reread all the posts and see it from the beginning.


163. KatrinaRitaWilmaZeta
12:53 AM GMT on January 11, 2006
hey hurricanechaser whats up
162. Raysfan70
12:50 AM GMT on January 11, 2006
Why is it that you must talk to people on here like we are all Stupid. And that you know it all. This sounds like the blog Pre Katrina that made all others leave Dr.Master's (and this is who it belongs to) and start there own. If you must continue you this can you please bring it to your own.
Thank You,
Member Since: July 28, 2005 Posts: 138 Comments: 57357
160. hurricanechaser
12:43 AM GMT on January 11, 2006
Hey cyclonebuster,

I'm trying to be understanding and patient, but PLEASE tell me where you get such an absurd idea as to think I wouldn't know that there is a direct correlation between sea surface temperatures and hurricane intensity.


Heres's your comment:


What you are saying is not true. There is a direct correlation to a hurricanes maximum wind speeds when compared to SSTs."

To my post saying...

Here's my comment once again to your question about whether I believed that a category five would definitely weaken over 75 degree water temperatures even down to a category one...

"First of all, intense hurricanes weaken themselves through internal dynamics and its rare for them to maintain such intensity very long even over optimal conditions."

That was an important statement about such intense storms.:)

"Secondly, your suggestion is obviously correct in theory, but it is still conceivable for a category five in an intensification phase moving fairly quickly over this small area you note could still retain its category five intensity and most certainly would not drop to a category one if thats how I interpret your initial post with this question."

To be as specific as possible, I was saying that it is STILL POSSIBLE for a category five hurricane to move over a small area of 75 degree waters at a fairly quick pace and still maintain category five status.

Of course, I know that a hurricane that stalls creates upwelling...please read my comments correctly.:)


159. hurricanechaser
12:30 AM GMT on January 11, 2006
Hey Bob,

If you want to truly stop global warming, you need to move the Earth farther away from the sun. There's your fix to stop this NATURAL function of climate variability known as Global warming.

I don't won't to be living in sub zero temperatures either so I think I will simply be thankful we have these alternating Global cycles myself.:)




157. hurricanechaser
12:22 AM GMT on January 11, 2006
Hey Everyone,

I can't stand talking with two faced and manipulative people who insist on belittling others and call them names. This is what I get while I'm trying to stop this back and forth jabbing which serves no real purpose.

*********** Original message follows: ***********
Sent by weatherguy03 at: 11:09 PM GMT on January 10, 2006

Play meterologist..Yeah right dude..I graduated from Rutgers, I dont know what you are talking about..I even went to school with someone on this blog...You are a joke!!!..Just watch what you are saying about me, ok. So is it Yes or No...Rebuild New Orleans...I know you dont want it rebuilt, because most Right Wing Facist Republicans like yourself would love to see it go away...But it isnt..Well for now Bush will ignore it, but it wont go away!!!...Have a nice day!!!

Hey Bob,

Well, I guess we can see why you are so upset...must be a major Liberal which is your right. You are absolutely wrong to stereotype my political views that are only Conservative on issues like abortion and gay marriage for example.

I am a moderate on social security, welfare, taxes, etc. So I'm hardly a right wing Fascist, which you must be saying I'm racist which is WRONG! Why do you insist on being rude with this name calling?

I have answered your question three times already...can't you read for goodness sake?

YOU ARE ABSOLUTELY WRONG TO ASSUME I WANT A CITY TO GO AWAY, UNLESS IT'S IN THE BEST INTERESTS OF THEIR SAFETY, it's called compassion, certainly understand why you don't get that!


You are the one who appears to be, "a joke" to quote your pleasantries.:)

And if you think I'm a joke...compete with me to see if your meteorological skills match mine.

Your arrogant, defensible, and rude attitude definitely seems to add an element of untrustworthiness, as to whether you did get a Masters in meteorology, for I have yet to see one intelligent post meteorologically speaking.

Anyone can have more than one screen name and manipulate the blogs, so your supposed friend on this blog couldn't prove much.


Viewing: 207 - 157

Page: 1 | 2 | 3 | 4 | 5Blog Index

Top of Page
Ad Blocker Enabled

Category 6™


Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

JeffMasters's Recent Photos

Fall Color in Pictured Rocks
Pictured Rocks Beach Day
Pictured Rocks dunes and clouds
Grizzlies in Lake Clark National Park