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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1441. Drakoen
7:38 PM GMT on July 25, 2007
the convection was more impressive this morning compared to now. It seems the cloud tops are being blown to the West.The convection has now taken on a more linear shape that the circular shape we saw this morning.

Member Since: October 28, 2006 Posts: 57 Comments: 29886
1440. Skyepony (Mod)
7:36 PM GMT on July 25, 2007
Texan who ignored evacuation order asked to pay for rescue ~ shot himself in the leg...
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1439. louisianaboy444
7:37 PM GMT on July 25, 2007
i'm going watch the tropical update on the weather channel lol....i just watch it for a laugh they probably won't even mention the BOC blob they will probably say Atlantic is quiet and not even show a map
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1438. Skyepony (Mod)
7:31 PM GMT on July 25, 2007
No indictment in Katrina hospital deaths
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1437. IKE
2:35 PM CDT on July 25, 2007
Posted By: Bamatracker at 2:34 PM CDT on July 25, 2007.
heavy rain for whom?


Texas and LA.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1436. Drakoen
7:33 PM GMT on July 25, 2007
looking at the vorticity analysis it appears higher at 850mb than at 700mb.
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1435. Bamatracker
7:34 PM GMT on July 25, 2007
heavy rain for whom?
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1434. Patrap
2:32 PM CDT on July 25, 2007
LOL
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1433. Bamatracker
7:32 PM GMT on July 25, 2007
Link

heres the link to the NAM
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1432. hurricane23
3:30 PM EDT on July 25, 2007
Yea and its the NAM a piece of garbage in my opinion when it comes to tropical cyclones.The spin in the GOM is in the mid-levels from what i see with a movement towards the NNW.

Some slight change for a TD but either way the result will be the same with heavy rainfall.
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1431. louisianaboy444
7:28 PM GMT on July 25, 2007
does anyone have the link to the NAM
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1430. Drakoen
7:29 PM GMT on July 25, 2007
Mississippi that is because that is the highest pressure in the given area.
In this situation, the pressure is lower of the coast of Texas lol.
Member Since: October 28, 2006 Posts: 57 Comments: 29886
1429. CJ5
7:25 PM GMT on July 25, 2007
Posted By: Patrap at 10:05 AM CDT on July 25, 2007.
Reason for concern...

70,000 folks still in FEMA trailers along the Northern Gulf Coast.



I hope not, but that problem is going to be a huge issue this season. I shudder to think the potential mess that could be upon us any day now.

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1428. Bamatracker
7:27 PM GMT on July 25, 2007
well atleast one model is showing it. I dont believe in forecasting exclusivly off models but I do like to see a couple showing a surface low forming out of a blob. The models can process a heck of lot more info than I can.
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1427. Drakoen
7:28 PM GMT on July 25, 2007
Posted By: hurricane23 at 7:28 PM GMT on July 25, 2007.

There is no surface low in the GOM at the moment but yes there are hints of some cyclone turning.


yes thats what i am saying...
Member Since: October 28, 2006 Posts: 57 Comments: 29886
1426. MississippiWx
7:27 PM GMT on July 25, 2007
Lol...1015 mb High Pressure isn't high pressure but there have been plenty of those, Drak.
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1425. louisianaboy444
7:25 PM GMT on July 25, 2007
well here in south louisiana they have raised the rain chances for thursday and friday with the comming of this tropical moisture streaming up from the gulf...our local meteorologist says development isnt out of the question
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1424. hurricane23
3:27 PM EDT on July 25, 2007
There is no surface low in the GOM at the moment but yes there are hints of some cyclonic turning.
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1422. Drakoen
7:25 PM GMT on July 25, 2007
Posted By: Bamatracker at 7:24 PM GMT on July 25, 2007.

do any of the models develop this thing in boc?


the NAM is the only model. None of the reliable model develop anything in the BOC.
Member Since: October 28, 2006 Posts: 57 Comments: 29886
1421. MississippiWx
7:25 PM GMT on July 25, 2007
Bama,

The NAM does...and so far, it has done basically what the NAM has said it would do. The GFS does have a bullseye of convection in South Louisiana in two days which could be this system.
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1420. Drakoen
7:23 PM GMT on July 25, 2007
1016mb isn't low. There may be low level turning but i do not see a SFC low evident. I would at least like to see the pressure lower at the buoy considering thats where the bulk of the moisture is.
The discussion Taz posted was based on the NAM.
Member Since: October 28, 2006 Posts: 57 Comments: 29886
1419. Patrap
2:25 PM CDT on July 25, 2007
Posted By: Patrap at 10:05 AM CDT on July 25, 2007.
Reason for concern...

70,000 folks still in FEMA trailers along the Northern Gulf Coast.

First and foremost....lead time even for a strong TS is problamatic.
No immediate concern..but the area should be monitored closely for development.
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1418. Bamatracker
7:23 PM GMT on July 25, 2007
do any of the models develop this thing in boc?
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1417. jamnkats
7:18 PM GMT on July 25, 2007
We had some really good wind and horizontal rain early this morning and tapering off after midday here on the East Yucatan penninsula. Not our normal weather. I don't know how strong the wind was, but it was enough to knock stuff down and blow stuff all over our palapa.
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1416. tampabayfish
7:22 PM GMT on July 25, 2007
I see a spin and its blowin like 20 kts down there... I'm goin to tape the windows...
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1414. MississippiWx
7:22 PM GMT on July 25, 2007
Franck...not trying to argue, but what is your basis behind saying it doesn't look tropical?
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1412. MississippiWx
7:21 PM GMT on July 25, 2007
Drak, I've seen plenty of Tropical Depressions with 1016 mb pressure.
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1411. franck
7:19 PM GMT on July 25, 2007
If a low does form in the GoM it'll probably be tonight. Otherwise it probably won't happen. The system is moving too fast. Doesn't appear tropical.
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1409. Drakoen
7:18 PM GMT on July 25, 2007
jp i mean't no low. 1016 is the pressure at the buoy.
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1408. Bamatracker
7:18 PM GMT on July 25, 2007
jp...you saying there is a surface low?
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1407. Bamatracker
7:17 PM GMT on July 25, 2007
jflorida...not quite sure what you are asking...can you clarify?
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1405. Patrap
2:16 PM CDT on July 25, 2007
GOES IR Loop of Gulf of Mexico
Link
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1404. Patrap
2:16 PM CDT on July 25, 2007
IMHO..LOL
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1402. Patrap
2:15 PM CDT on July 25, 2007
DRak...you need to use more eyes and less BS.
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1400. Drakoen
7:12 PM GMT on July 25, 2007
the pressure is at 1016mb no low lol.
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1399. MississippiWx
7:08 PM GMT on July 25, 2007
Hey guys...might want to take a look at the new Ramsdis loop that's right over the top of the BOC disturbance...an obvious spin is present now. The loop is pretty short though..

Link
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1398. tampabayfish
7:08 PM GMT on July 25, 2007
I know pressures remain high and conditions aren't ideal, but there does seem to be a small twist in the BOC blob on visible... I'll throw 5% at it and see if it sticks...
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1397. CJ5
7:06 PM GMT on July 25, 2007
So the update now is saying the waves 38/15 and 62/14 have cyclonic turing. That is new. The 38/15 has had increased convection today, perhaps it will continue tonight.
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1394. guygee
7:02 PM GMT on July 25, 2007
Posted By: jphurricane2006 at 7:02 PM GMT on July 25, 2007.
"um I always thought the 24 hour shear tendency showed what the shear has done the past 24 hours, not what it will do the next 24 hours"
Sorry about that everyone JP is right about the shear tendency link a gave:
Link

It is not a forecast.
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1393. ShadesOfAqua
7:03 PM GMT on July 25, 2007
Thanks Bama.
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1392. IKE
2:00 PM CDT on July 25, 2007
Updated marine discussion from Tallahassee, Fl.....

"Marine...winds and seas will remain generally light and onshore
through the short term period..but could increase by the weekend if
a surface low develops in the western Gulf of Mexico and tightens the
pressure gradient as currently prognosticated by the NAM.
The convective
mass needed to accomplish this is already present and moving
northward in the Bay of Campeche...so this will require monitoring
over the next few days...especially if the deep convection persists
and additional models converge towards the NAM solution.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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
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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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