By: Dr. Jeff Masters , 12:33 PM GMT on July 24, 2007

The July 2007 issue of Scientific American has an article called "Warmer Oceans, Stronger Hurricanes" (referred to as "Warmer Water, SUPER HURRICANES" on the cover). The article is written by Dr. Kevin E. Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research, and a lead author on the landmark 2007 climate report issued by the UN's Intergovernmental Panel on Climate Change (IPCC). The article makes the case that "evidence is mounting that global warming enhances a cyclone's damaging winds and flooding rains." The article presents some solid evidence to substantiate that point of view, which I will share below. However, I was disappointed in the general tone of the piece, which was over-hyped and did not paint an objective view of the current scientific thinking on the global warming/hurricane issue.

The hype
First off, the reader is hit with a dramatic full-page artist's depiction of the global super-hurricane of the future--a massive 5000-mile diameter Caribbean storm the size of North America. The storm's 200-mile eye is wider than the Florida Peninsula! Whoa, I said when looking at the whopper "SciAmicane". No doubt many readers perusing the magazine, trying to decide whether to buy it, had the same reaction and plunked down their $5 to read about this grim threat. OK, lets talk reality here. The largest tropical cyclone on record, Supertyphoon Tip of 1979, had a diameter of 1380 miles--less than one third the size of the SciAmicane. A storm like the SciAmicane cannot physically exist on Earth unless the oceans were to super-heat to about 122°F (50°C). Only an asteroid impact or similar calamity could create such a hypercane. Even the most extreme global warming scenarios do not heat the oceans to 122°, so the SciAmicane is there to sell magazines, not to illustrate what global warming might do to hurricanes.

Figure 1. Comparison of sizes: the Earth, the largest tropical cyclone on record (Supertyphoon Tip of 1979, 1380 miles in diameter), and the recently discovered hurricane-like vortex on Saturn (the Saturnicane). The "SciAmicane" is about the same size as the Saturnicane--5000 miles across.

The article also calls attention to 2004, when "an unprecedented four hurricanes hit Florida, and 10 typhoons made landfall in Japan". I've erroneously made this statement, too, but the truth is that Japan was hit by only four typhoons in 2004. Ten tropical cyclones that were of typhoon strength at some point during their life did hit, yes, but six of these had decayed to tropical storm or tropical depression strength by the time they hit Japan. The article then refers to a "consensus explanation" emerging to explain recent hurricane activity patterns, and "that explanation forebodes meteorological trouble over the long term." I'd say that the issue is still very much under dispute. In fact, the consensus statement on hurricanes and climate change adopted by the World Meteorological Organization in December 2006, in response to the recommendations of a panel of 125 hurricane researchers was thus: "Though there is evidence both for and against the existence of a detectable anthropogenic signal in the tropical cyclone climate record to date, no firm conclusion can be made on this point." Trenberth's article gives a list of four publications to read in the "more to explore" section, but none of these include the recent articles that call into question the strength of the global warming/stronger hurricane connection. (I apologize for not reviewing the many excellent articles that have appeared on this subject of late!)

The good science
There's quite a bit of good science in the article, which is worth reading if one keeps in mind its biases. In particular, I like the discussion of how global warming has affected precipitation and atmospheric water vapor. The 0.6°C (1.0°F) rise in Sea Surface Temperatures (SSTs) globally since 1970 has increased water vapor in the atmosphere by 4%, thanks to increased evaporation. This in turn has led to an 8% increase in global precipitation. Trenberth makes the point that no given hurricane can be blamed on global warming, but one can say 8% of a given storm's rainfall is due to global warming. There's also a nice discussion about how weaker than normal trade winds over the tropical Atlantic in 2005 caused less evaporational cooling than normal, allowing the ocean to heat to record temperatures. Finally, the conclusion of the article is one I certainly agree with:

We would all be wise to plan for more extreme hurricane threats.

Both theory and computer models predict a 3-5% increase in hurricane winds per degree C increase in tropical SSTs, and there is concern that the actual increase may be much more than this.

Jeff Masters

For a technical treatment of hypercanes, see Dr. Kerry Emanuel's paper, Hypercanes: a possible link in global extinction scenarios.

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1540. weathermanwannabe
5:26 PM EDT on July 25, 2007
"Anticipaaation....Anticipaaayation...."..Our average yearly rainfall average for North Florida is down between 15-20 inches, so many of us are hoping for the rain to swing up from the Gomex over the next few days....
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1539. weatherblog
9:23 PM GMT on July 25, 2007
The CATL wave does have nice, symmetrical, structure. But it has to mantain heavy convection for at least another 24 hours...not to mention, it may not even have a low at the surface.

But, still, it will probably become 98L very soon...I'm predicting by tomorrow night.

Also, I'm guessing, if the wave holds together and is even MORE organized, by tomorrow it'll probably be mentioned in TWO. And, I'm guessing they would say "some slow development is possible..."
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1538. RL3AO
4:24 PM CDT on July 25, 2007
Little development does not mean TD.

They would use something like "A tropical depression may from in the next day or so" if they thought it would develop.
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1537. StormJunkie
9:24 PM GMT on July 25, 2007
I concur for the most part 07, imho
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1536. IKE
4:24 PM CDT on July 25, 2007
But there's a lot of moisture in the western GOM.
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1535. RL3AO
4:18 PM CDT on July 25, 2007
We have a line of buoys at 38W so we have that to look forward to.
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1534. StormJunkie
9:22 PM GMT on July 25, 2007
Evening all ☺

30w still looks decent and there is still model support for it amzin. Out of the two, that's my horse, speaking of horses :~)
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1533. Blink
9:22 PM GMT on July 25, 2007
The Nam 18Z brings something up the coast of Tx. Only model making that assumption. I clearly don't see anything coming off that mess in the GOM. Shear is way too strong at the moment.

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1532. IKE
4:20 PM CDT on July 25, 2007
Posted By: amazinwxman at 4:12 PM CDT on July 25, 2007.
been talking about the BOC mess but what is going on with the 30W wave anything? How is it looking this evening?

I was gonna say the same thing 07 said...the structure of that CATL wave is impressive...has backed off on the convection slightly...but, it has definite possibilities.
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1531. weatherblog
9:18 PM GMT on July 25, 2007
TWO said "little development expected"...

Well, becoming a TD or TS is "little development"...so, maybe some development is still possible.
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1527. amazinwxman
9:11 PM GMT on July 25, 2007
been talking about the BOC mess but what is going on with the 30W wave anything? How is it looking this evening?
1526. FloridaRick
9:10 PM GMT on July 25, 2007
THanks RL3...I should have guessed Knew the S and The L wasn't sure about A
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1525. RL3AO
4:08 PM CDT on July 25, 2007
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1524. Shrap
8:55 PM GMT on July 25, 2007
Well Bama, I live in Pcola and I sat through Ivan's eye wall dragging right across me. I am still in the "stayers" group for the most part, only because I am in a really good location (highest elevation in Pcola),good structure and no kids.

The whole experience of such a powerful storm is incredible (albeit, not for the timid). But I saw the dresuction at the beach and water ways, and many many people would be insane not to leave, even in minor storms.
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1523. RL3AO
4:07 PM CDT on July 25, 2007
At least the NHC mentioned it.
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1522. guygee
9:04 PM GMT on July 25, 2007
On the use of QuickSCAT in tropical and ocean storm forecasting.

Since this has been a recent topic of interest, I thought I would look at what the experts had to say about the use of QuickSCAT in tropical and ocean storm forecasting. I started with this publication Earth Science and Applications from Space: Urgent Needs and Opportunities to Serve the Nation (2005)pg 20 where I read: "Accurate ocean winds also improve weather forecasts and storm warnings. The use of QuikSCAT wind data, for example, improved National Weather Service forecasts of the four hurricanes that devastated the southeast United States in 2004 and marine warnings to ships at sea [10]. Looking at reference 10, I saw this quote: "A forecaster from the National Centers for Environmental Predictions Tropical Prediction Center stated that without QuickSCAT they would be forecasting in the dark.". A link was given to back up the statement, and after some searching I found the current link to the Satellite Measurements of Ocean Vector Winds: Present Capabilities and Future Trends, NOAA/NASA Workshop, Miami, Florida, February 8-10, 2005.

What is available on this site are Powerpoint Presentations given by meteorological scientists from government, academia and industry. Particularly interesting are two presentations that were given by Senior Hurricane Specialists Richard Knabb and Jack Beven. I would encourage anyone interested in the use of satellite-based scatterometers and their use in tropical and ocean storm prediction to peruse and download some of these presentations; they are very informative and full of good case studies and beautiful graphics. Here I just want to focus on the conclusions of the two NHC Senior Hurricane Specialists.

Richard Knabb's presentation is titled "Impacts of QuikSCAT on Tropical Prediction Center Operations" and is available for download here. First he reviews "Huge Gaps in Surface Data in TAFB Areas of Responsibility" and how QuickSCAT helps fill these gaps. Next he makes these three points:

"-QuikSCAT data used during forecast shift at least 75% of the time.

-When QuikSCAT led to changes in the wind velocities in analyses and forecasts, the revised winds were higher about 65% of the time.

-Primary reasons for QuikSCAT data not being used on a particular forecast cycle are lack of timeliness and/or lack of data over the feature/area of interest.

Next Dr. Knabb speaks to "QuikSCAT Impacts on TAFB Products" and among several comments he makes this statement: "Losing scatterometer data, without a viable replacement, would be severely detrimental to TAFB marine analyses, forecasts, and warnings." Among Dr. Knabb's conclusions are the statements:

"-Continued operational availability of scatterometer data is greatly needed in TPC operations.

-TPC forecasters have gained substantial experience with scatterometer data and have learned to extract much useful information hopefully an investment in the future.

-More than one instrument is needed due to large gaps between swaths in the Tropics and due to infrequent passes over a feature of interest.

Dr. Bevin's presentation was shorter than Dr. Knabb's. In his summary he points out:
"- QuikSCAT has been useful in many cases for operational applications: Center detection, location, wind radii.

-Rain impacts and lack of rain information severely limits further use of QuickSCAT winds.

In his "Requirements for Future Missions" Dr. Bevin requests "More Converage!", "Less ambiguity in the measurements" and a solution to the rain contamination problem.

Finally, it is worth briefly reviewing a presentation made by Joe Sienkiewicz, who is the Ocean Prediction Centers Science and Operations Officer. It is apparent that QuickSCAT is even more important for extratropical ocean storm prediction than for tropical storm prediction, perhaps due to a lesser problem with rain contamination that might be expected with extratropical storms. The presentation "The Operational Impact of QuikSCAT Winds at the NOAA Ocean Prediction Center" contains some startling revelations, such as
"-When QuikSCAT was available, changes were made to: 68% of the events in the Atlantic, 50% of the events in the Pacific, where Event- Lows, Highs and Wind areas (speed and aerial extent)"
"-Can differentiate between significant and extreme winds (Storm versus Hurricane Force)."
"-QuikSCAT winds have changed the way we do business"

For further information and publications on QuickSCAT from the Ocean Prediction Center see their page on QuikSCAT Publications.
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1521. FloridaRick
9:02 PM GMT on July 25, 2007
Can any of you great ones tell me what SAL is. I mean I know the definition but what does the SAL Stand for?
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1520. louisianaboy444
9:05 PM GMT on July 25, 2007
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1519. Fl30258713
9:03 PM GMT on July 25, 2007
Posted By: thelprogressivemoles at 8:46 PM GMT on July 25, 2007.

jphurricane git off ya high horse troll. Just because others have diff. opinions doesn't give you the right to attack and pontificate...IF....yes...IF you were that good you would have a better job...

I don't think JP has a high horse. I'm pretty sure he doesn't have enough land to take care of any horses.
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1518. Tazmanian
9:01 PM GMT on July 25, 2007
530 PM EDT WED JUL 25 2007



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1517. louisianaboy444
8:56 PM GMT on July 25, 2007
yeah it shows it rolling off the African coast and looks to have it maintaining itself but then again this is far out take this with a grain of salt we best stop talking about it because it is indeed a long ways out and dont want to freak people out
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1516. Tazmanian
8:56 PM GMT on July 25, 2007
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1515. Blink
8:55 PM GMT on July 25, 2007
Here's what the GFS shows in 6 days time. A Surface low with 1008 mb.

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1514. louisianaboy444
8:51 PM GMT on July 25, 2007
yeah i know just thought it was an interesting feature...and i'm new to all these models so maybe someone with a little more experience can look for me....78 hours out on the GFS doesnt it show our CATl wave with a surface low and a 1008 pressure? i might be reading it wrong so maybe someone can go check that out for me thanks!
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1513. wanzewurld
8:51 PM GMT on July 25, 2007
Hmmmmmm, There's a little spot that bears watching:
66W - 14N 07-25-2007 15:00 CDT
Strong surface development, not a lot of shear and upper-level high pressure nearby.
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1511. Tazmanian
8:48 PM GMT on July 25, 2007
uh oh
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1510. louisianaboy444
8:45 PM GMT on July 25, 2007
no its not showing a surface low but...for our people in here that are desperate to see something lol i got something but take it with a grain of salt.....5 days out on the GFS shows a very strong surface low rolling off the African coast with 1008 pressure and tracking across the Atlantic
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1507. jamweather
8:41 PM GMT on July 25, 2007
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1506. Tazmanian
8:41 PM GMT on July 25, 2007
but dos are CATL wave have a sfc low and all of that?
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1505. louisianaboy444
8:40 PM GMT on July 25, 2007
i've just noticed the GFS 42 hours at has the pressure at only 1012 for our BOC disturbance but has the CATL wave getting alot stronger
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1504. NeverPanic
8:37 PM GMT on July 25, 2007
Heres the link, just copy/paste

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1503. Blink
8:37 PM GMT on July 25, 2007
Ya, the pressure clearly shows there's still not a surface low. It has been steady all day.
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1502. louisianaboy444
8:37 PM GMT on July 25, 2007
is it possible that a surface low could form overnight?
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1501. Tazmanian
8:35 PM GMT on July 25, 2007
Conditions at 42002

Wind Direction (WDIR): SE ( 130 deg true )
Wind Speed (WSPD): 25.3 kts
Wind Gust (GST): 31.1 kts
Wave Height (WVHT): 4.9 ft
Dominant Wave Period (DPD): 6 sec
Average Period (APD): 5.1 sec
Mean Wave Direction (MWD): S ( 170 deg true )
Atmospheric Pressure (PRES): 30.00 in
Pressure Tendency (PTDY): +0.00 in ( Steady )
Air Temperature (ATMP): 76.8 F
Water Temperature (WTMP): 84.4 F
Dew Point (DEWP): 75.9 F
Combined plot of Wind Speed, Gust, and Air Pressure
Continuous Winds TIME
2:50 pm SE ( 132 deg ) 26.6 kts
2:40 pm SE ( 133 deg ) 27.6 kts
2:30 pm SE ( 135 deg ) 28.0 kts
2:20 pm SE ( 142 deg ) 28.0 kts
2:10 pm SE ( 144 deg ) 30.1 kts
2:00 pm SE ( 139 deg ) 26.8 kts

if olny if we had a sfc low
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1498. Tazmanian
8:29 PM GMT on July 25, 2007
tx dos not need more rain send it to me and send tx some snow
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1497. louisianaboy444
8:27 PM GMT on July 25, 2007
i was just looking at the NAM and they have it approaching the mid texas coast 36 hours out but the pressure is only at 1012 and no low im mostly likely looking at the wrong one huh lol
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1494. sullivanweather
8:24 PM GMT on July 25, 2007
Not looking good for Texas....
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1493. Tazmanian
8:20 PM GMT on July 25, 2007
98L sooon? huh?
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1492. Drakoen
8:15 PM GMT on July 25, 2007
Lousiannaboy if you are using the vorticity on the FSU page you look for something circular with high vorticity.. hard to explain.

If you use the GFS on the NHC page its easier. You use the MSLP look at the wave you are watching and see what the model does with it in the loop. If the model is picking up on something it usually shows a low and gives the pressure. You will also see the circular isobars around the system.
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1491. jamweather
8:14 PM GMT on July 25, 2007
where do you go to monitor buoy in the GOM?
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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