Warmer Water, SUPER HURRICANES

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

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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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1791. Drakoen
1:11 AM GMT on July 26, 2007
definately need to watch this. has a circulation and could increase the convection during diurnal max.
Member Since: October 28, 2006 Posts: 57 Comments: 30727
1790. stormybil
1:10 AM GMT on July 26, 2007
jp if you go to page 16 and 17 you will see i started to post about this blob lastnight it was looking good in the first 3 hours and more after i also said the front will push it more ne toward fla imo
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1789. CaicosRetiredSailor
9:02 PM EDT on July 25, 2007
Good evening,

Seeing a lot about climatology, average seasons, etc. etc.

I can pass on the "hurricane mantra" which has been passed from generation to generation here in the islands for many many years:

June, Too Soon

July, Stand By

August, Come They Must

September, .....Remember

October, All Over

CRS
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1788. philliesrock
9:11 PM EDT on July 25, 2007
Check out CL's blog. I'm posting conditions from the Nor'Easter (wink wink) hitting me right now.
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1787. Tazmanian
6:11 PM PDT on July 25, 2007
yes 03 98L vary soon by 0300
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1786. sporteguy03
1:11 AM GMT on July 26, 2007
JP,
You see the rainbow today?
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1784. Tazmanian
6:08 PM PDT on July 25, 2007
no 98L yet but i think we may by 0300 on the navy site
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1783. weatherboykris
1:09 AM GMT on July 26, 2007
Posted By: StormJunkie at 1:05 AM GMT on July 26, 2007.

lol Taz, Merry Christmas ☺

The 06z also seemed weaker with the wave. As I stated earlier, I think that the 6/18z GFS runs often conflict the 0/12z runs? Not really sure why, or if this is true, but it seems that way to me. I have noticed it with track, intensity, and genesis.


It is true.I'ts because the 00z and 12z runs get their upper air data from balloons and the 06z and 18z runs get their's from less accurate satellite estimates.
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1782. sporteguy03
1:08 AM GMT on July 26, 2007
Taz,
98L Soon?
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1780. Buhdog
1:07 AM GMT on July 26, 2007
hey SJ
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1777. Blink
1:04 AM GMT on July 26, 2007
Where's our gift's? lol

The BOC convection seems to be heading more NNE tonight. Shear is still high north of the convection. I've been looking at some shear maps and I still believe it will have a hard time developping.
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1776. cajunkid
8:05 PM CDT on July 25, 2007
happy birthday and merry kwanzaa
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1775. philliesrock
9:05 PM EDT on July 25, 2007
Merry Christmas to you, too. Go to CL's blog for the real Christmas party.
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1774. StormJunkie
1:01 AM GMT on July 26, 2007
lol Taz, Merry Christmas ☺

The 06z also seemed weaker with the wave. As I stated earlier, I think that the 6/18z GFS runs often conflict the 0/12z runs? Not really sure why, or if this is true, but it seems that way to me. I have noticed it with track, intensity, and genesis.
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1773. pottery2
9:03 PM AST on July 25, 2007
Merry Christmas, Taz. LOL
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1772. Buhdog
1:01 AM GMT on July 26, 2007
Looks like Gulf Wave is getting much better organized and breaking away from the trough.

Anyone else buyin?
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1771. moonlightcowboy
12:59 AM GMT on July 26, 2007
Tropical wave roughly along 40w/41w S of 15n moving W 10-15 kt.
Satellite imagery indicates an elongated E/W zone of low-level
cyclonic turning extending about 300-400 nm either side of the
wave axis along 11n. The wave is also evident in the SSM/I-
derived tpw product with some cyclonic turning and a surge of
moisture S of 15n.


...dry air (but less prevalent) above 15n, blob is also still tracking west, some "upper level" shear, but low shear at the sfc and mids with tendency relaxing.
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1770. sporteguy03
1:02 AM GMT on July 26, 2007
Yes the Convection in the BOC it seems to be moving ENE is that because of shear of the cloud tops?
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1766. sonofagunn
12:55 AM GMT on July 26, 2007
The CIMSS shows shear decreasing in the path of the BOC blob. Also, the shear forecast shows improving shear conditions in that area.

I would assume it is headed towards the North Gulf of Mexico coastline, but I don't really have a clue.

Shear forecast

CIMSS
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1765. Tazmanian
5:44 PM PDT on July 25, 2007
Merry Christmas
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1764. Tropicnerd13
12:56 AM GMT on July 26, 2007
i updated it. goodbye for today.
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1763. ryang
8:57 PM AST on July 25, 2007
Philles, great forecast track, i tend to agree.
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1762. JLPR
12:58 AM GMT on Julio 26, 2007
that bigtropical wave its getting close to get out to water and seems to be holding together that one should be very interesting
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1761. sporteguy03
12:56 AM GMT on July 26, 2007
StormW,
Is that 1018 High going to keep the convection away from the Eastern Gulf?
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1760. IKE
7:56 PM CDT on July 25, 2007
Posted By: Drakoen at 7:56 PM CDT on July 25, 2007.
is the GFS still showing development in the CATL?


It's backed off some on the latest run...for what that's worth...has it going toward the keys.
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1759. moonlightcowboy
12:56 AM GMT on July 26, 2007
http://manati.orbit.nesdis.noaa.gov/dataimages21/cur/zooms/WMBds32.png

Tropical wave will be introduced along 27w S of 17n moving W
about 15 kt. There are several indications of this wave. 1...a
weak signal is noted in the dakar sounding between 00z and 12z
on the 23rd. 2...a signal is noted in the sal sounding between
12z on the 24th and 00z on the 25th mainly in 850-900 mb level.
3...a 1946z Quikscat pass shows a weak circulation centered W of
the cape verdes near 13n27w. Scattered moderate convection is
from 12n-15n between 25w-28w.
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1757. Drakoen
12:55 AM GMT on July 26, 2007
is the GFS still showing development in the CATL?
Member Since: October 28, 2006 Posts: 57 Comments: 30727
1754. IKE
7:53 PM CDT on July 25, 2007
Posted By: jphurricane2006 at 7:50 PM CDT on July 25, 2007.
the area in the western gulf is already mentioned in the TWO


Looks to be heading further east then what the NAM runs have had it going.
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1752. Drakoen
12:51 AM GMT on July 26, 2007
lol philliesrock.
Member Since: October 28, 2006 Posts: 57 Comments: 30727
1750. guygee
12:41 AM GMT on July 26, 2007
MichaelSTL - I agree with you a lot of the factors are present to make this an active year. I was going to post this picture to make a similar point about how early in the season it really is.

I am especially concerned about the very deep warm anomaly in ocean temperatures in the NW Caribbean, through the Yucatan Straits and the SE Gulf. That is firewater for any storm passing through that much-traveled route.
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1749. philliesrock
8:49 PM EDT on July 25, 2007
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1748. benirica
12:49 AM GMT on July 26, 2007
how much longer do we think before the NHC mentions it
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1744. StormJunkie
12:44 AM GMT on July 26, 2007
benric, the convection should flare up and down on it. One other thing is the amount of model support it has had over the past couple of days.

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1743. Miamiweather
12:44 AM GMT on July 26, 2007
Hey StormW you got mail
1742. moonlightcowboy
12:43 AM GMT on July 26, 2007
L8R, Patrap! Get some good rest!
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1741. pottery2
8:41 PM AST on July 25, 2007
Very good post, STL
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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.

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