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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1391. Tazmanian
7:03 PM GMT on July 25, 2007
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 25 2007



GULF OF MEXICO...
ANOTHER ACTIVE WEATHER DAY IN THE GULF TODAY ALTHOUGH THE FOCUS
HAS SHIFTED W. LIGHTNING DATA...RADAR...AND SATELLITE DEPICT
SCATTERED SHOWERS AND TSTMS OVER MOST OF THE BASIN W OF 88W. THE
ACTIVITY IS MOST CONCENTRATED IN A CLUSTER OF SCATTERED MODERATE
CONVECTION NOW DRIFTING N THROUGH THE BAY OF CAMPECHE AND THE
YUCATAN...WITHIN 90NM EITHER SIDE OF THE LINE 26N88W 24N93W
21N96W. THERE MAY BE A SOME LOW LEVEL CONFLUENCE IN THE AREA BUT
OVERALL THE SURFACE FLOW ON THE LARGE SCALE IS ANTICYCLONIC
AROUND AN ATLC RIDGE ATTEMPTING TO BUST THROUGH. A HINT OF LOW
LEVEL CYCLONIC TURNING IS ALSO NOTED JUST OFFSHORE TUXPAN
MEXICO. THE UPPER SUPPORT...ON THE OTHER HAND...IS MUCH MORE
FAVORABLE WITH THE FLOW HIGHLY DIFFLUENT BETWEEN THE BROAD UPPER
LOW OVER TEXAS AND AN UPPER HIGH OVER WRN CUBA. SFC HIGH
PRESSURE IS EXPECTED TO FORM OVER THE NE GULF THROUGH THU AND
MOVE LITTLE THROUGH FRI. THIS WILL PRODUCE LIGHT WINDS OVER THE
NE PORTION WITH MODERATE SE FLOW IN THE WRN PORTION.
SHOWERS/TSTMS EXPECTED TO CONTINUE AFFECTING THE WRN GULF
THROUGH THU WITH THE UPPER SUPPORT ONLY SLOWLY WEAKENING AND
LOWER TO MID LEVEL ENERGY APPROACHING WITH THE TROPICAL WAVE
NEAR THE YUCATAN.


--------------------------------------

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS TILTED ALONG 16N38W 11N40W 5N40W MOVING W NEAR
13 KT. THIS WAVE WAS ADJUSTED SLIGHTLY TO THE E BASED ON ITS
APPEARANCE IN VISIBLE SATELLITE IMAGERY THIS MORNING. A BROAD
ZONE OF LOW LEVEL CYCLONIC TURNING IS NOTED FROM 10N-15N BETWEEN
36W-44W. DEEP CONVECTION REMAINS MINIMAL.

TROPICAL WAVE IS MOVING THROUGH THE WINDWARD ISLANDS ALONG 62W S
OF 14N. THE WAVE IS MOVING QUICKLY W 20-25 KT AND EXHIBITS SOME
SLIGHT LOW LEVEL CYCLONIC TURNING. ISOLATED MODERATE CONVECTION
IS MOVING INTO AND THROUGH THE SE CARIBBEAN FROM 11N-14N BETWEEN
60W-66W.

A WEST CARIBBEAN TROPICAL WAVE IS ALONG 87W S OF 21N MOVING W
NEAR 20 KT. SCATTERED SHOWERS AND TSTMS ARE OVER MUCH OF THE NW
CARIBBEAN N OF 15N W OF 82W...AND ARE NOW MOVING THROUGH BELIZE
AND THE ERN YUCATAN PENINSULA. ANOTHER CLUSTER OF MODERATE
CONVECTION IS FROM 14N-16N BETWEEN 80W-82W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N16W 11N35W 8N35W 9N43W 11N58W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OVER THE COAST
OF AFRICA AND ADJACENT WATERS FROM 11N-15N BETWEEN 14W-18W.
SCATTERED MODERATE ALSO FROM 8N-11N BETWEEN 20W-23W. SIMILAR
CONVECTION IS WITHIN 120NM EITHER SIDE OF THE AXIS BETWEEN
28W-34W...WHICH MAY BE ASSOCIATED WITH A LOW AMPLITUDE TROPICAL
Member Since: May 21, 2006 Posts: 5089 Comments: 114055
1390. weathers4me
7:03 PM GMT on July 25, 2007
5%
Member Since: May 24, 2007 Posts: 0 Comments: 118
1387. tampabayfish
6:56 PM GMT on July 25, 2007
Well said indeed bamabeach. I think there is a false sense of security in the Tampa Bay area because they "made it through the florida four in '04", but this area was merely scraped. Not many people around that can remember a true landfall (1935 I think). Some of the emergency managers around here hypothesize that Pinellas County would, at least temporarily, become and island if a 4 or 5 hit. I dont think people can conceive that...
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1386. guygee
6:58 PM GMT on July 25, 2007
I don't think the future looks good for development of the disturbance in the Bay of Campeche. First look at the the strong Upper Level Winds currently just to the north.

Then notice that the Deep-Layer Wind Shear to the north of the system is westerly at about 15-25 kts attm.

Finally see that the 24hr Shear Tendency calls for an additional 5-10 kts increasing shear to the north of the system.

If the system persists down in the BOC without moving very far north for a couple of days I think the factors that may be in its favor are the forecasts for continuing upper-level divergence and a building high pressure in the NE Gulf, and perhaps the small ULL that is forming near the Big Bend area that looks to be dropping south that may affect its track later if the BOC convection does not dissipate.

IMHO.
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1385. borlando
6:54 PM GMT on July 25, 2007
bama, when my dad had parkinsons (he has passed now) we went up for frances to tennessee for him. this was after charley. when jeanne was supposed to hit melbourne even my good ol dad stayed. we just got him a generator and gas. he wouldn't let us stay there with him, he was a stubborn man.
1384. Bamatracker
6:57 PM GMT on July 25, 2007
shades...it depends on the strength of the system on what level actually steers it. weaker storms stay lower and strong storms can get steered by 200 level
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1383. ShadesOfAqua
6:57 PM GMT on July 25, 2007
Question - If hectopascals (hPa) are equivalent to millibars for measuring air pressure, which level on the steering current maps is most influential for actually steering a system (ie. wave, TS, or hurricane) and which level should I check on the map?
Thanks to all of you for your insights. I enjoy this blog - reading your posts and learning from you.

~ back to lurking ~
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1382. Bamatracker
6:51 PM GMT on July 25, 2007
bamabeach....i live in Mobile and I'm in the Staying group. Actually I go about 20 miles N to the in-laws but still in the county. It really depends how far away from the coast you are, what type of structure you are in, and your elevation. Would I ride one out at gulf shores...no...but I'm not going to run to Montgomery either because I have safe places here to ride it out.
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1381. Bamatracker
6:50 PM GMT on July 25, 2007
I dont look at it much either JP...just thought it was appropriate for the convo.
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1376. Bamatracker
6:48 PM GMT on July 25, 2007


according to this less than 1%
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1375. bamabeach
6:02 PM GMT on July 25, 2007
I live on the Alabama coast and can tell you that I don't mess around when it comes to this. I board the house, board the dogs, cut the horses loose to the back pasture and off we go.
I have a family and will A)NOT jeopordize their safety in any way and B)become a burden for rescue people to come and save us when we should have been GONE in the first place.

I know down here those that say "I'm stayin" say it ONCE. After that it's "I'm leavin".

The problem is many people move into an area like ours and will be experiencing this for the first time so they are often the "i'm stayin" people. Until they become a member of that group one time. After that they leave.
don't get me wrong. There are those that have stayed thru them ALL like my 88 year old neighbor.He scares the crap out of me but he's not leaving and there is no talking him out of it.
But there are alot of "newbies" that just don't get it until they go thru it.
Secondly, there are those that THINK they have gone thru a storm so they feel confident they can stay thru the next one.
I put a lot of Mobile Al. folks in that catagory. When Ivan came in it ducked east sparing Mobile and when Katrina came in they just got the scraping ends of that monster.
My step son lives there and is in that catagory. "Oh, I went thru Ivan". I say "no you didn't, it went east at the last minute and was a walk in the park over there". Talk to the people in Perdido Key and Orange Beach about staying around. You won't find many there. That's where the teeth of Ivan bit down.
Afterwards it's wet, hot, no air, mosiquito's everywhere, and it stinks. You can stay if you want. "I'm leavin".
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1374. FormerFloridian
2:45 PM EDT on July 25, 2007
Posted By: emagirl at 2:43 PM EDT on July 25, 2007.
so what is everyone's % chance on us having a storm out of these systems we are watching??


0% for the ones in the BOC. 10% for the one in the Atlantic.
1372. CJ5
6:41 PM GMT on July 25, 2007
Posted By: weatherbrat at 6:32 PM GMT on July 25, 2007.
Predicting weather is a inexact science,


fixed
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1371. Bamatracker
6:43 PM GMT on July 25, 2007
10%
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1370. emagirl
6:42 PM GMT on July 25, 2007
so what is everyone's % chance on us having a storm out of these systems we are watching??
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1369. CJ5
6:21 PM GMT on July 25, 2007
Posted By: Patrap at 6:15 PM GMT on July 25, 2007.
Popcorn anyone?


No kidding...this place will turn into a funny farm when invests start getting named.
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1368. Blink
6:39 PM GMT on July 25, 2007
I saw that Michael, but the pressure remains steady for now. Here's the latest steering currents map, someone was asking for it.
Link
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1365. RL3AO
1:35 PM CDT on July 25, 2007
It is a tropical weather blog...people speculate.
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1364. weatherbrat
6:27 PM GMT on July 25, 2007
Okay. Lamaz anyone? Everyone take a deep breath and blow it out slowly....good....now take another deep breath and blow it out slowly....good. We're not going to have a Cat 5 today, so relax a little.

Let's all be patient and see what is going to come of these waves/blobs.

Questions being asked here are very important and informative. That's good, but some people are being very speculative about what's going to happen. Predicting weather is a true science, so remember, let's get the facts, continue to observe and we will all learn as we go.

Thanks to all those who are here to help educate others about hurricanes, tropical storms, depressions and the like! I appreciate all of you!
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1363. DaytonaBeachWatcher
6:31 PM GMT on July 25, 2007
but they really are not that smart anyway.


lmao
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1362. brazocane
6:28 PM GMT on July 25, 2007
Is the shear forcasted to weaken in the western gulf? Yesterday I thought I read somewhere it was going to relax in about 48-72 hours.
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1360. Bamatracker
6:29 PM GMT on July 25, 2007
BOC needs a surface low first. Shear getting low doenst mean anything without that.
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1359. weathers4me
6:21 PM GMT on July 25, 2007
Thanks Drakoen. I know I'm a novice but I'm learning from you guys. You are all very knowleable when it comes to this stuff. It's hard to read those models because I get confused between a low and a TS or hurricane. How are the maps supposed to be read? Thanks
Member Since: May 24, 2007 Posts: 0 Comments: 118
1358. Blink
6:27 PM GMT on July 25, 2007
The convection in the BOC does not look bad but it needs to settle down and spin instead of being blown off by sheer. A long shot but worth watching.
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1357. ryang
2:27 PM AST on July 25, 2007
Drak what does that mean low amplitude?

Weak, convection minnimal.
Member Since: August 25, 2006 Posts: 329 Comments: 12397
1356. Drakoen
6:26 PM GMT on July 25, 2007
Posted By: amazinwxman at 6:26 PM GMT on July 25, 2007.

Drak what does that mean low amplitude?


the energy associated with the wave is low.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1355. franck
6:23 PM GMT on July 25, 2007
You're certainly right PR. Wonder why that is?
I noticed you spotted the GoM thing when it was nearer the BoC. Did you have a premonition with that? I believe in premonitions.
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1354. Tropicnerd13
6:23 PM GMT on July 25, 2007
i guess that everyone is going to use that as a catch phrase now. "i was ignored! :( " well thanks and goodbye.
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1353. H2OMaker
6:24 PM GMT on July 25, 2007
New member here, I've been lurking, reading, and learning for over 5 years. The handle is relative to my employment, and also seems appropriate to weather. I live near Houston... for now.
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1352. Drakoen
6:24 PM GMT on July 25, 2007
Posted By: jphurricane2006 at 6:24 PM GMT on July 25, 2007.

lol i dont think this will curve out to sea


anyway whats going on in the BOC?


high shear. enhanced convection from an anitcyclone.
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1350. amazinwxman
6:25 PM GMT on July 25, 2007
Drak what does that mean low amplitude?
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1349. Drakoen
6:23 PM GMT on July 25, 2007
Posted By: TropicalMan07 at 6:19 PM GMT on July 25, 2007.

Drak, Which is off of africa already and in the atlantic water's? and whats your thought on it, do you agree its a healthy looking wave? with potential? (already has a low associated with it)


yes the one at 30w. it is healthy but the NHC thinks its a low amplitude tropical wave. It has potential. The models are forecasting development in the area so we will have to watch it.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1347. Tropicnerd13
6:20 PM GMT on July 25, 2007
oh he he... use me as a joke. yup that settles it. yall are truly the nicest people ever!
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1346. amazinwxman
6:15 PM GMT on July 25, 2007
Thanks alot neverP that was helpful and so much better then googling.
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1345. Drakoen
6:20 PM GMT on July 25, 2007
weathers4me the GFS long range does not show curving out to sea...
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1344. DaytonaBeachWatcher
6:19 PM GMT on July 25, 2007
Posted By: Patrap at 6:14 PM GMT on July 25, 2007.

The most convection and potential is in the GOM.To concentrate on miniscule lil waves and 300hr model runs is crazy. Focus on the nearest potential always...anything in the C Atlantic is days out from even the Antilles....


true enuff right now but it is more interesting to watch em all...:-)
Never turn your back on the weather!
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1342. Tropicnerd13
6:15 PM GMT on July 25, 2007
oh my god it will take me 5 years to go thru that site!!! well im about to leave for today. getting tired. gonna go for a walk. talk later.
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About JeffMasters

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