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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539. Drakoen
1:28 AM GMT on July 25, 2007
Member Since: October 28, 2006 Posts: 57 Comments: 30615
538. Drakoen
1:21 AM GMT on July 25, 2007
Posted By: StormW at 1:20 AM GMT on July 25, 2007.

Posted By: Drakoen at 1:14 AM GMT on July 25, 2007.

StormW what do you think about the wave(s) in the CATL?

IMO...I think both may have some potential. The one at 35W looks fair on Dvorak IR. The one behind it has better coverage and the convective area is a little more symmetric. If anything does happen though...one's going to be fighting the other


yea thats what i thought. The one behind it is a little more impressive. Oh and do you think a low is trying to form with that wave around 30W 10N?
Member Since: October 28, 2006 Posts: 57 Comments: 30615
537. KEEPEROFTHEGATE (Mod)
1:18 AM GMT on July 25, 2007
keep watch over the y/t just coming off shore gettin to that warm water
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535. Patrap
8:18 PM CDT on July 24, 2007
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534. Patrap
8:18 PM CDT on July 24, 2007
Yes Oschner
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533. MrNiceville
1:17 AM GMT on July 25, 2007
Pat - not OMC???
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532. Patrap
8:17 PM CDT on July 24, 2007
Was on Bonnabel Blvd above Vets pre-K
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531. MrNiceville
1:15 AM GMT on July 25, 2007
Thanks - makes me feel a little better about my ability to see the screen without reading glasses (need them for books and menus, tho)...
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530. Drakoen
1:15 AM GMT on July 25, 2007
there is lower level convergence and upper level divergence.
Link
Member Since: October 28, 2006 Posts: 57 Comments: 30615
529. LSU
1:16 AM GMT on July 25, 2007
Ahh
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528. Patrap
8:15 PM CDT on July 24, 2007
Kenner Near The Hospital..on West Esplanade
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527. Patrap
8:15 PM CDT on July 24, 2007
Nova's the grill Guard too
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525. LSU
1:14 AM GMT on July 25, 2007
Patrap, where are you in NOLA? I'm uptown on Jefferson and Magazine.
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524. Patrap
8:14 PM CDT on July 24, 2007
Pork Ribs,,,sauced to Perfection..LOL
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523. NaplesPatty
1:13 AM GMT on July 25, 2007
was that a nice juicy steak on the grill Pat?
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522. Drakoen
1:13 AM GMT on July 25, 2007
StormW what do you think about the wave(s) in the CATL?
Member Since: October 28, 2006 Posts: 57 Comments: 30615
520. MrNiceville
1:11 AM GMT on July 25, 2007
Sorry 'bout that - try 92W21N (right in that general vicinity)...
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519. Drakoen
1:10 AM GMT on July 25, 2007
Member Since: October 28, 2006 Posts: 57 Comments: 30615
518. RL3AO
8:09 PM CDT on July 24, 2007
A good old plastic rain tube.
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517. Patrap
8:09 PM CDT on July 24, 2007
7
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516. Rodek
1:00 AM GMT on July 25, 2007
Hello all... My question of the night:


When the local weather report says we got 1 inch of rain, there sure seems to be alot of water on the gound for only an inch of liquid. Just how is precipitation amount measured?

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514. scwindsaloft
1:03 AM GMT on July 25, 2007
To all you knowlegables:

would someone please explain to me how to interpret convergance and divergance wind charts?
I understand their definition, not their application or interpretation.
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512. Patrap
8:02 PM CDT on July 24, 2007
To be sure.I follow my own road..with direct Obs.Models are for funsies. Those of us who have seen the BOC and GOM get wiggy quick.Know what to look for.I dont do the forecast thing.Im a weather enthusist.No such thing as a amateur met...
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511. DDR
1:02 AM GMT on July 25, 2007
hello guys, anything interesting in the tropics?
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510. Patrap
7:59 PM CDT on July 24, 2007
Best bring a lil Help..Nova dont Kinder to strangers. >
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508. HIEXPRESS
12:57 AM GMT on July 25, 2007
BBL Eureka Break.
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507. Drakoen
12:58 AM GMT on July 25, 2007
Member Since: October 28, 2006 Posts: 57 Comments: 30615
506. MrNiceville
12:55 AM GMT on July 25, 2007
Honestly, I'm not impressed with the convection coming off the YP - that happens quite often and dies. In fact, the same thing happened last night at this time and it got shredded the minute it moved off the coast.

Having said that, I'll be back in NOLA starting next Wednesday, Pat. If you can wait, I'll help you strap the pontoons to the trailer...
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505. Miamiweather
12:58 AM GMT on July 25, 2007
Hey storm you got mail
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504. Patrap
7:54 PM CDT on July 24, 2007
GOES WV Loop of Tropical Basin
Link
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503. Patrap
7:50 PM CDT on July 24, 2007
To be sure..the GOM can go zippa de do da in a day..best to keep a wary eye on the BOC.

5 day pressure graph..Buoy 42002 Western GOM
Link
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500. HIEXPRESS
12:46 AM GMT on July 25, 2007
Posted By: Murko at 12:44 AM GMT on July 25, 2007.

Wouldn't larger drops have a lower terminal velocity, due to increased wind resistance?

Apparently not.
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499. StormJunkie
12:49 AM GMT on July 25, 2007
THE GFS APPEARS THE FARTEST EAST

lmao ☺
Member Since: August 17, 2005 Posts: 26 Comments: 16874
498. Drakoen
12:49 AM GMT on July 25, 2007
UKMET
Member Since: October 28, 2006 Posts: 57 Comments: 30615
497. MrNiceville
12:43 AM GMT on July 25, 2007
StormW -

Your opinion, please...

in the loop that Pat just posted, there are two "clear" areas - one immediately behind the dissipating wave and one immediately preceding the new convection coming off the YP.

Is it possible that the SE clear area is a small L that's attempting to close off?

There is nothing to support that idea on any of the maps and forecasts that I'm looking at. In fact, with the shear indicated to be 20kts+, I don't expect anything to form. But it seems rather serindipidous, given the NAM and GFS indications earlier.

I don't believe in chance...
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495. JLPR
12:46 AM GMT on Julio 25, 2007
thats right drakoen there seems that there is nothing else to watch
:D
Member Since: September 4, 2007 Posts: 36 Comments: 5223
494. Drakoen
12:46 AM GMT on July 25, 2007
Member Since: October 28, 2006 Posts: 57 Comments: 30615
493. HIEXPRESS
12:32 AM GMT on July 25, 2007
Posted By: GRDRATNAVARRE at 12:18 AM GMT on July 25, 2007.
HIEXPRESS - It's the inertia, total area and run off rate of the roof that would matter. I don't think that it would matter much if it were 1 inch per hour heavier rainfall as far as the roof goes. It's always the wind that gets the roof. If it finds a way under it will lift it. The extra down force of the rain would probably help to keep the roof on, but not much.

Navarre - Yes, that is what I was getting at, a large increase in inertia from a small increase in rainfall rate. I have seen buildings (roof still on & intact) crushed flat like a grape by what appeared to me to have been a direct hit by a microburst before it mushroomed out at the surface. The instantaneous rates can be, IMHO higher than you would expect, so any little restriction in the roof drainage system would compound the problem. Never say always. Been to many aftermaths?
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492. Drakoen
12:43 AM GMT on July 25, 2007
I'm back. Seems that the focus tonight is that wave in the CATL.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
491. Murko
12:39 AM GMT on July 25, 2007
Posted By: HIEXPRESS at 12:03 AM GMT on July 25, 2007.
...Now we add bigger drops (with a higher terminal velocity)...


Wouldn't larger drops have a lower terminal velocity, due to increased wind resistance?
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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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