The future of flooding

By: Dr. Jeff Masters , 10:06 PM GMT on February 19, 2008

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Are storms getting more extreme due to climate change? That is a difficult question to answer, since reliable records are not available at all in many parts of the world, and extend back only a few decades elsewhere. However, we do have a fairly good set of precipitation records for many parts of the globe, and those records show that the heaviest types of rains--those likely to cause flooding--have increased in recent years. According to the United Nations' Intergovernmental Panel on Climate Change (IPCC) 2007 report, "The frequency of heavy precipitation events has increased over most land areas". Indeed, global warming theory has long predicted an increase in heavy precipitation events. As the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 IPCC report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. Satellite measurements (Trenberth et al., 2005) have shown a 1.3% per decade increase in water vapor over the global oceans since 1988. Santer et al. (2007) used a climate model to study the relative contribution of natural and human-caused effects on increasing water vapor, and concluded that this increase was "primarily due to human-caused increases in greenhouse gases". This was also the conclusion of Willet et al. (2007).

More water vapor equals more precipitation
This increase in water vapor has very likely led to an increase in global precipitation. For instance, over the U.S., where we have very good precipitation records, annual average precipitation has increased 7% over the past century (Groisman et al., 2004). The same study also found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events over the U.S. in the past century. Kunkel et al. (2003) also found an increase in heavy precipitation events over the U.S. in recent decades, but noted that heavy precipitation events were nearly as frequent at the end of the 19th century and beginning of the 20th century, though the data is not as reliable back then. Thus, there is a large natural variation in extreme precipitation events.

Pollution may contribute to higher precipitation
It is possible that increased pollution is partly responsible for the increase in precipitation and in heavy precipitation events in some parts of the world. According to Bell et al. (2008), summertime rainfall over the Southeast U.S. is more intense on weekdays than on weekends, with Tuesdays having 1.8 times as much rain as Saturdays during the 1998-2005 period analyzed. Air pollution particulate matter also peaks on weekdays and has a weekend minimum, making it likely that pollution is contributing to the observed mid-week rainfall increase. Pollution particles act as "nuclei" around which raindrops condense, increasing precipitation in some storms.

The future of flooding
It is difficult to say if the increase in heavy precipitation events in recent years has led to more flooding, since flooding is critically dependent on how much the landscape has been altered by development, upstream deforestation, and what kind of flood control devices are present. One of the few studies that did attempt to quantify flooding (Milly et al., 2002) found that the incidence of great floods has increased in recent decades. In the past century, the world's 29 largest river basins experienced a total of 21 "100-year floods"--the type of flood one would expect only once per 100 years in a given river basin. Of these 21 floods, 16 occurred in the last half of the century (after 1953). With the IPCC predicting that heavy precipitation events are very likely to continue to increase, it would be no surprise to see flooding worsen globally in the coming decades.

Jeff Masters

References
Bell, T. L., D. Rosenfeld, K.-M. Kim, J.-M. Yoo, M.-I. Lee, and M. Hahnenberger (2008), "Midweek increase in U.S. summer rain and storm heights suggests air pollution invigorates rainstorms," J. Geophys. Res., 113, D02209, doi:10.1029/2007JD008623.

Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003, "Temporal variations of extreme precipitation events in the United States: 1895.2000", Geophys. Res. Lett., 30(17), 1900, doi:10.1029/2003GL018052.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64.85.

Milly, P.C.D., R.T. Wetherald, K.A. Dunne, and T.L.Delworth, Increasing risk of great floods in a changing climate", Nature 415, 514-517 (31 January 2002) | doi:10.1038/415514a.

Santer, B.D., C. Mears, F. J. Wentz, K. E. Taylor, P. J. Gleckler, T. M. L. Wigley, T. P. Barnett, J. S. Boyle, W. Brüggemann, N. P. Gillett, S. A. Klein, G. A. Meehl, T. Nozawa, D. W. Pierce, P. A. Stott, W. M. Washington, and M. F. Wehner, 2007, "Identification of human-induced changes in atmospheric moisture content", PNAS 2007 104: 15248-15253.

Trapp, R.J., N.S. Diffenbaugh, H.E. Brooks, M.E. Baldwin, E.D. Robinson, and J.S. Pal, 2007, Severe thunderstorm environment frequency during the 21st century caused by anthropogenically enhanced global radiative forcing, PNAS 104 no. 50, 19719-19723, Dec. 11, 2007.

Trenberth, K.E., J. Fasullo, and L. Smith, 2005: "Trends and variability in column-integrated atmospheric water vapor", Climate Dynamics 24, 741-758.

Willett, K.M., N.P. Gillett, P.D. Jones, and P.W. Thorne, 2007, "Attribution of observed surface humidity changes to human influence", Nature 449, 710-712 (11 October 2007) | doi:10.1038/nature06207.




Winter Flooding (Jmroh)
This is the result of extreme snowmelt and 4 inches of rain.
Winter Flooding
Yellow River Starke County Indiana (StarkeHistorian)
Kankakee Game Preserve, 10 Mile Road: The Yellow River crested this morning at 12.14' at the US35 bridge at 11:45AM. This was 2.14' over flood stage. The record is 15.3 Jan 1, 1991.
Yellow River Starke County Indiana

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401. surfmom
12:36 PM GMT on February 26, 2008
Well I am zooming off to get kid to school and myself to work. See you guys later.
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400. surfmom
12:25 PM GMT on February 26, 2008
Patrap - give you applause for your work and words this morning!

Good Morning ALL!!! Great to get good weather infor. this AM. Thanks Patrap (gomex loop) thanks StormW --seeing what's ahead in the weather for the day makes my planning so much easier! I use to just read 50% chance of rain and really still be cluelss as to what is going on.

This AM, I reviewed all your information and I know I better get my self in gear and get to the barns asap --work all the horses first thing this AM and save the tack cleaning, and inside jobs for the afternoon.
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399. surfmom
12:19 PM GMT on February 26, 2008
skyepony, I had wondered what had happened to Madagascar - the pictures of Ivan just sitting on that island was very disturbing - the reality of the numbers very sad, very concerning.
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398. Patrap
6:23 AM CST on February 26, 2008
GOM IR Loop ..Link
Member Since: July 3, 2005 Posts: 426 Comments: 129089
393. Tazmanian
7:58 PM PST on February 25, 2008
by the way dos any one no where dr m ran off too???
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392. Skyepony (Mod)
3:24 AM GMT on February 26, 2008
Levi~ When most plants are exposed to high amounts of CO2 the mechinism that takes it in shrinks, like how your pupils get small in alotta light. Take Chem for science majors if ya hadn't & follow with biochem. It really pulls together the big picture.



Cyclone toll in Madagascar rises to 44ANTANANARIVO, Madagascar -- The death toll has risen to 44 and the number of homeless is up to 145,000 more than a week after a cyclone tore through this island in the Indian Ocean, Madagascar's government said Monday.

Areas on the eastern side of the island remained cut off by flood waters. Seven major roads were impassable and bridges have been destroyed, hampering attempts to deliver relief, according to the Ministry of Transport.

Cyclone Ivan lashed Madagascar on Feb. 17 with torrential rain and winds of up to 140 miles per hour.

The hardest-hit region is Fenerive Este, where one out of nearly every three residents lost their homes and 70 percent of buildings have been destroyed. Emergency medical supplies have been exhausted on island of Sainte Marie, a popular tourist resort that is home to 19,000, officials said.

Madagascar now faces food shortages after 37,000 acres of rice fields were flooded in the region of Alaotra Mangoro, which provides nearly a third of the island's staple food.

A relief effort is under way to provide rice, yogurt, cheese and money to parts of the east coast. The US has donated $100,000.

Madagascar, the world's fourth-largest island, is regularly struck by cyclones and there are fears that global warming may exacerbate the cyclone season. Last season was the worst on record -- six cyclones killed about 150 people.

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390. fire831rescue
1:32 AM GMT on February 26, 2008
That's cool. I just can't see where the majority of scientists around the world are pointing fingers at people, scaring them by saying, "it's you." On the other hand, I don't think politicians should be using their pull in government to push certain subjects onto people. I know I don't take to kindly to having religion pushed on me and I, myself, am a Christian. Same goes for other special intrests, especially when it comes from the mouth of politicians. Remember, Politic when divided into it's latin meaning, Poli means many and a tick is a blood sucking creature.
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389. Patrap
7:28 PM CST on February 25, 2008
Im neutral on the matter fire.

Dont mistake the links and accepted data on the subject matter as my personal view.
That is known only to my conscience.
I only link the info. I dont gather the data.

Member Since: July 3, 2005 Posts: 426 Comments: 129089
388. fire831rescue
1:18 AM GMT on February 26, 2008
Patrap, I do believe climate change is taking place, but I do find it very hard to believe that it is all caused by man as so many have said. I also find it very hard to believe that it is all caused by "greenshouse gases." I think it's a combination of Earth's natural cycles, the planet's distance and tilt in relation to the sun and some human factors. Not saying that humans have absolutely no impact, but it seems quite far fetched to think the humans and only humans are to blame for what happens on Earth. When you take all of the variables into account, it seems as if there is no one single causing for the warming or cooling of the planet. Whether it be what I discussed earlier with the distance and tilt of the Earth to the effect of "greenhouse gases", it all seems to be many different variables that are causing what has been called "global warming." It is very possible in the future, we could reach a "peak" temperature and the Earth's temp could fall again. Truth is that no one knows for sure what is happening. It's all one big guess as to what is causing our planet's temp to go up. I don't just look at everything from one angle and say that's what it is. I know there are many ways to reach the same result.
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385. Patrap
6:15 PM CST on February 25, 2008


Welcome to the Weather Underground's new Climate Change page!
We're just getting started, so keep checking back over the next few months for new additions.

Climate Change
A scientific look at global climate changes. Link
Member Since: July 3, 2005 Posts: 426 Comments: 129089
384. fire831rescue
10:48 PM GMT on February 25, 2008
Yes, pottery. Read it. Saw the big MIGHT there. But my thing is that we are always fed a bunch of things being called fact and told we must act on it, when they don't really know who or what is affecting anything.
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383. fire831rescue
10:45 PM GMT on February 25, 2008
I know about the city island effect. Hmm. It goes like this. Because pavement and concrete both get very hot in the sun and tend to hold in that heat longer than the surrounding vegitation and let the heat escape over a longer period of time, therefore acting as a heater on the earth's surface, bringing the temp up. Wow.
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382. pottery
6:43 PM AST on February 25, 2008
OK, but read my last sentence above, again, Fire.
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381. Patrap
4:40 PM CST on February 25, 2008
Well the fact is accepted that the Global temp is rising..and it correlates to the Burning and pumping into the Atmosphere Globally,pollutants,greenhouse gases,CFC's..heavy metals, and God knows what all 365/24/7.

And maybe check out the City Heat Island effect, if you dont think we influence the weather too.

The urban heat island (UHI) effect occurs when city temperatures run higher than those in suburban and rural areas, primarily because growing numbers of buildings have supplanted vegetation and trees. Moreover, human activity itself generates heat.

Link

And here too. Link

Out fer suppertime. Been fun.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
380. fire831rescue
10:32 PM GMT on February 25, 2008
Well, that's what I've been trying to get at is that we're all fed the notion that we ARE causing it and we NEED to cut back for our protecting and survival. Truth is that no one knows for sure. Instead of just looking at it from a manmade standpoint, as has been done all along, I'm looking from the standpoint that climate doing change over time and we don't need man's help for that to happen. Look at the ice ages. What happened between them? Oh, I got it. There were too many cavemen burning inside their caves. This created a lot of greenhouse gases resulting in global warming and that's what happened to the dinosaurs. Hahaha. It was the caveman's fault that they died. Yes, I'm being sarcastic for a reason. To prove a point. It's all a theory until it's proven fact. We need to look at it more like this: "The THEORY of Global Warming"
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379. Patrap
4:31 PM CST on February 25, 2008
How Old Is The Earth, And How Do We Know?

The generally accepted age for the Earth and the rest of the solar system is about 4.55 billion years (plus or minus about 1%). This value is derived from several different lines of evidence.

Link
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378. pottery
6:23 PM AST on February 25, 2008
Ok Fire, but the thing is that, to me, volcanoes, fires, etc are " natural " occurences that play a part in the overall scheme of things. They sometimes cost lives and property but so what.?
The "unnatural" activity that seems to have some effect is the emmissions that patrap referred to, along with a lot of others created by us. There is no 'Proof " that these emmissions are causing this or that to happen.
I do feel that it may be wise to consider that they very well MIGHT be having an effect, and that if there is any doubt, then we should err on the side of caution, and try to emit less.
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377. fire831rescue
10:24 PM GMT on February 25, 2008
The thing about what the "scientists" are trying to do with the "GLOBAL WARMING" issue is like this: You can't take 30, 50, 100 or even 500 years worth of study and tell what will happen tomorrow. The Earth is millions, if not billions of years old. We need a little more study to find out if our "scientists" are correct. Give 'em a little more time. Say a million years. By then, they should have enough data to tell us what happened in the past. (And that's all they'll find out.)
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376. Patrap
4:29 PM CST on February 25, 2008
Im well aware of natural variability. And Im well aware of the earths Celestial and Orbital Mechanics round Sol.Were closet to Sol in Jan ..furthest in July.The Axial tilt determines seasonal Heat and Cold.Not Orbital closeness to Sol.

The warming is occurring.As to the extent the Man-made processes are contributing...There in lies the crux..so the debate and science continues.
I dont believe in alarmist's,nor do I believe in Politicians. They both way to Loud and over hyped.And usually... it's the people who suffer from the contributions both make Globally.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
375. atmoaggie
10:17 PM GMT on February 25, 2008
Sorry about the long-winded defense of the ozone hole chemistry. That is what my degree work was all about. I am more familiar with that subject than I would like to be.
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374. fire831rescue
10:20 PM GMT on February 25, 2008
Sorry I lost you, pottery. Was trying to tie everything into one little neat package. But you know how it goes. My mind gets to goin 90 to nothing on a subject, wanders a few feet and starts on something related to the discussion but seems somehow off topic and detached.
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373. fire831rescue
10:13 PM GMT on February 25, 2008
That's all fine and dandy, Patrap, but what about other things that would dump gases into the atmosphere. I could name a few. Forest fires. Volcanoes - above ground and under sea. You know those thing aren't a constant. If that was the case, I do believe there wouldn't be any place for us to live for all the lava. And we'd be dodging forest fires more than the Californians do now. Point is that we're spending too much time and money trying to blame ourselves for something that could very well be a natural occurance. Refer to previous post about Earth's orbit around the sun. This may clear what I was saying up just a little.
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372. Levi32
1:09 PM AKST on February 25, 2008
fire831 yes I agree with all that......we're going off of a couple centuries of not even 100% reliable weather records....and we're coming out of an "ice age" and what-not........I just hate how political it's all become.
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371. pottery
6:10 PM AST on February 25, 2008
Fire831. You raised some good points, then you lost it when you went algoring. Forget the messenger, look at the message.
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370. Patrap
4:12 PM CST on February 25, 2008
Records for the issue go way back further than 30 years. Ships from the Europeans and around the Globe have kept records,as well as ice core sampling, which shows worldwide distribution of pollens and other temperature sensitive plant life.And Sea Floor coring as well as sedimentary sampling give evidence to past Peaks and valleys in the earths past. The argument isnt over the Observed warming..as much as to the rise of Fossil Fuel/Man influenced burning that correlates to the warming.

Where does the constant outporing of Billions of Combustion Process go IE, Autos and such?..
To Fairy LAnd?
..or the Exhaust from Coal Fired Plants Globally that also run 24/7 365 go?
No ..it goes into the Atmosphere Globally.Not Locally only.


Its a cause in effect thing were observing.
Not fantasy Football.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
369. fire831rescue
10:05 PM GMT on February 25, 2008
I know. The tropical weather blog is for just that... Tropical weather. But you can't discuss tropical weather without the Earth's climate being mentioned. And when the Earth's climate is mentioned, "GLOBAL WARMING" comes up. And I start thinking about Al Gore and his Multi-Million dollar mansion using all of that electricity while teeling us "commoners" we need to use less. WHAT A HYPOCRITE!!!!
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368. pottery
6:01 PM AST on February 25, 2008
True, Pat.
Hopefully, there is enough funding for the research to take into account all the influences that affect the Hurricane season.
Truth is, the parameters are changing so fast, ( whatever the reasons) that the researchers are always a step behind.
How is life with you ? I saw you moved house ?
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367. fire831rescue
9:57 PM GMT on February 25, 2008
Levi32, I just get tired of having "GLOBAL WARMING" shoved down my throat as a pure fact. Truth is that trying to prove something in a 30 year study without looking at all of the different angles just makes "scientists" look like morons once they are proved wrong. I think a lot of people, mostly politicians, jumped on the "GLOBAL WARMING" bandwagon before anyone was able to do a more thourough research on the topic. (And ya'll know that the "scientists" are goning to agree more with whoever is writing their paychecks.) My thing is that there are so many other reasons for the Earth's temp other than "GLOBAL WARMING".
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366. pottery
5:59 PM AST on February 25, 2008
Good post Levi32
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365. Patrap
3:57 PM CST on February 25, 2008
Its all intertwined in the big Pic pottery. Canes are part of the Big Pic equation. They take the latent heat and Moisture and transport it to the Higher latitudes as part of the Global Thermodynamic picture. Many factors can and do affect the subtle and large factors in this process.Including what you mention about the Atlantic and its currents and the Artic Ice Melting. Ice Melt from the Poles will have an effect.As to what extent, I would not know.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
364. pottery
5:56 PM AST on February 25, 2008
Maybe I should put it this way.....If there was no North Polar melt, then what would the Atlantic SST have been in 2007.
No change ?
Lower ?
What ?
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363. pottery
5:08 PM AST on February 25, 2008
No icebergs in the GOM !
My point was, that if it is true that the Polar Ice cap reduced in size last summer, and that would tend to suggest that a fair amount of ice ( A billion cubic yards ) melted, then that cold water must have gone somewhere. Into the Guflstream perhaps ? Into the GOM maybe?
I'm not looking to score points Pat, but asking for some thoughts on the matter.
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362. Levi32
12:42 PM AKST on February 25, 2008
Also, has anyone thought about CO2 touted as a greenhouse gas. If we are putting off so much CO2, which plants require to survive, why aren't our trees and others plants growing at an exponential rate.

Just so ya know I agree with your post and I hate GW debates so I won't get into one but I just wanted to comment on this little tidbit that you said.

Massive amounts of CO2 are not necessarily going to bomb plant growth. There has always been plenty....and plants need many ingredients besides CO2 to go through photosynthesis...the most obvious of these is sunlight and water....and unless the other factors increase along with the CO2 plants will not necessarily grow exponentially. If temperate climates had sun all day long like the poles do in the summer then there would be an infinite amount of sunlight and CO2 for the plants to work with and then they might grow exponentially....but that isn't the case.

Sorry guys I'm studying biology...I hate it lol....but that's my 2 cents on the plant part :D
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361. atmoaggie
9:32 PM GMT on February 25, 2008
Ummm, the ozone layer bit not a theory anymore. Yes, it was being depleted for about a month over the poles at the onset of sunlight returning to that pole...early spring, but it would then recover as soon as the polar stratospheric cloud dissipated. The cloud offered surfaces upon which the chlorine radical chemistry could occur.

It would have worsened if we didn't reduce the release of very stable gases capable of surviving a trip to the poles (long) and up to the stratosphere (much longer) only to then release their free chlorine atom. The holes still happen and will continue for 100 years or so...the gases in this chemistry are VERY stable and do not react until sunlight not filtered by any of the troposphere comes into play.

Lightning does have a part, it creates NOx, which reacts with certain volatile organic compounds (VOCs, like turpenes from pine trees) to create tropospheric ozone naturally. Industrial sources can increase the VOCs to a point at which more tropospheric ozone is produced...to sometimes unhealthy levels (it IS a toxin). This ozone NEVER makes the trek to the polar areas and doesn't make it anywhere close to stratospheric levels. It is not a stable compound and reacts with NO (with a little sunlight) to make NOx again, which is brown. A good guess of where ozone is high is where is the brown smog is present.
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360. fire831rescue
9:03 PM GMT on February 25, 2008
In response to the issue of the Global Warming THEORY... Has anyone taken into account that Earth's orbit around the sun changes from almost circular to eliptical, which in turn, would change the distance of the earth from the sun and could drastically change Earth's temperatures. How about the poles. Yes, they tilt but they also wobble. The wobble goes from almost circular to eliptical, as well. These two combined, would cause the angle the earth tilts and distance from the sun to change from time to time, which could also be a explanition for why the earth's temperatures are going up or down. Also, has anyone thought about CO2 touted as a greenhouse gas. If we are putting off so much CO2, which plants require to survive, why aren't our trees and others plants growing at an exponential rate. And on the subject of Global Warming, the ozone layer. Whenever lightning strikes anywhere on Earth, ozone is produced. In theory, if we are "depleting the ozone layer" shouldn't it be gone by now? Ever notice how anything humans do to Earth, it seems to be undone by weather or by nature. Seems as if the earth has a natural way of undoing what humans do or create. Nothing can outsurvive nature but nature itself. Nothing on earth that is manmade is permanent. Take a look at the facts that have been gathered. Global Warming... Yeah. The Earth's temp has only changed maybe 1 degree in the 150 years that the US has been recording temps here. Scaring everyone into thinking they're all doing something wrong to push an agenda is no way to go about doing business. Sorry for the rant but I had to get that off my chest.
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359. Patrap
3:08 PM CST on February 25, 2008
Havent seen many Bergs in da Gulf of Mexico lately.
But I'll keepa me eye out.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
358. pottery
5:01 PM AST on February 25, 2008
Further...do we know what effect the introduction of all that cold water from the Arctic is having on Atlantic SST in the Summertime ??? When I add a block of ice to my drink, the whole glass of stuff cools down.........
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357. pottery
4:37 PM AST on February 25, 2008
atmoaggie, you raise some interesting points. But firstly, 300 years ago if a storm did not landfall, it probably went un-noticed. Also, it isnt a notion that the Sahara is expanding, its a factual thing. The " why " is the doubt. Re the Dust coming from there into the Tropical Atlantic, there are still conflicting ideas about what effect it will have/ is having.
Some surmise that the presence of the dust will help to generate more storms, as the dust particles could act as "seeds" around which water droplets will form. Another view ( I go with this one ) is that the dust is accompanied by a cloud of hot, dry air, and this will absorb most of the moisture that is in the area, effectively drying up any potential Trop[ical Weather system in the Atl.
Interestingly, it was also thought that the dust would tend to block sunlight, and cause cooler SST. Experiecne is showing that the surface temps have actually risen when the dust is present. So although one would think that the higher surface air temps would result in more moisture in the air and therefore stronger storms, the accompanying dry air seems to be cancelling this out.

The thing is most interesting.
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356. atmoaggie
8:36 PM GMT on February 25, 2008
Guys, I saw this work where the amount of dust deposited in the western US has dramatically increased with westward expansion and settlement. Interesting...but,

What about the notion that the Sahara has been expanding. This is something the GW crowd loves to say and blame on your gas mileage. My thought is this: If there was substantially less dust over the tropical Atlantic (from Africa) 300 years ago, wouldn't we all expect the possibility of more TCs developing back then (compared to now)? Especially early in the season, right?

OK, assuming GW really does happen, so how does the positive influence of higher SSTs compare to the negative influences of more shear AND more dust? Do we really have a net positive feedback here? I am not so sure.

SST is a requirement and higher values (or depth of 26.5C isotherm) leads to stronger storms. High shear trumps the SST requirement, though. Also, I am fairly sure that hydrophillic dust at mid or upper levels will also act a bit like a trump to the other 2 conditions.

Please correct me if I have it wrong about the GW presumption of expanding deserts.

Thoughts?
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355. StormHype
7:18 PM GMT on February 25, 2008
I saw this old 1993 political Van Halen video yesterday and saw something that was prudent to share here.

Watch this video at note what it says at timecode 1:36 thru 1:39

Van Halen - Right Now

It says "Right now is just time between Ice Ages" Interesting. That was the mainstream scientific community's mindset during most of the 1970's thru the time this video was made in 1993. Now, it's only 15 years later and all people can talk about is global warming. Hmmm.... Maybe Al Gore needs to make a music video to sell his agenda.

BTW, try convincing people in the mid-west about global warming theory this winter. Hard sell.
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354. weathermanwannabe
1:40 PM EST on February 25, 2008
Hey All....I'll be in the Western Florida Panhandle for the next few days (startng tommrow) so we'll see if any significant threats develop (SPC has us in the moderate risk category right now)......Tornadoes suck, but, all the rain over the past several weeks up here has been a blessing as we do not currently have any rain deficits for the year and we can always use the water......As far as any thoughts on the coming season, what I have learned over the last three years on this Blog during Hurricane Season (from Dr. Masters and many of the well-versed regulars on here) is to expect the unexpected (which is usually the case with Mother Nature) so I am giving less and less credence to the annual predictions (from Grey/NHC/Bastardi, etc.)and basically take the wait and see approach which usually means when an actual depression forms somewhere when the big factors (SST's-Convection Persistance-Waves-Frontal Remnants- Shear Values, etc.) start to "gell" during any given week during the heart of the Season......Just too many factors out there that can change during any season, IMHO, to even rely on the long-term predictions issued during the Season..........BWE...Bastardi predicted a huge risk for the Gulf last year and it never came to pass......You just never know and I hope that the wishcasters don't turn the Blog into a Zoo this year.....
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353. MichaelSTL
11:03 AM CST on February 25, 2008
Also, as far as the effects of La Nina on hurricane season go, a strong La Nina is NOT favorable for a very active season; in fact, strong La Nina seasons tend to be like what we had last year (which was very similar to 1988, even down to some of the individual storms, which had a similar strength La Nina). Often, the Atlantic cools down during strong La Ninas, and as recent research has found, this has a big impact on other conditions (even if the Pacific is cooler, the Indian Ocean also plays a big part,last year it was very warm and that has a similar effect to El Nino in the Pacific). As for U.S. impacts, a neutral season is generally the worst (like 2005, which began with a weak El Nino that decayed to neutral by hurricane season and cooled to a weak La nina by the following winter - probably the worst thing that can happen for the U.S., as the El Nino warms things up, then a neutral pattern favors increased activity and U.S. strikes; a slow decline to a weak La Nina by the end of the season has also been linked to increased activity).


From hurricanealley.net:

4. The most active seasons in terms of storm number numbers and percentage of named storms achieving hurricane and major hurricane status are those with a neutral with cold bias

7. The years with the highest number of storms on average are those classified as neutral with a cold bias

8. The years with the most landfalls by tropical systems are those that are considered neutral

11. The years with the greatest percentage of landfalls that are major hurricanes are those ranked as neutral
Member Since: February 22, 2006 Posts: 94 Comments: 32744
352. MichaelSTL
10:45 AM CST on February 25, 2008
What havoc will she reak this spring?

Probably a near-historic severe weather season, considering what we have already seen... and this (I have also posted about this in my blogs before, as early as last February):

The Super Outbreak occurred at the end of a very strong, nearly record-setting La Nina event.

(speaking of record-setting, the current La Nina has the potential to set a record for the strongest La Nina during February)


La Nina Probably Contributed to Huge Tornadoes

Cooler than normal ocean temperatures in the mid-Pacific, called La Nina, have caused many bizarre weather effects in North America, including record snow and monster tornadoes.

Start Date: 5/10/99

A rash of killer tornadoes that swept through the midwest United States in early May -- including at least one giant F-5, the most powerful category, packing winds approaching 300 miles per hour -- were driven in part by La Nina, scientists say. The cold-water condition in the mid-Pacific ocean, also credited with dropping a record 91 feet of snow on mountains in Washington state this winter, can be expected to produce more devastating tornadoes in the coming months. Already the number recorded this season is running ahead of normal expectations.
"The signal is there," said Steve Byrd, science officer for the National Weather Service in Omaha, Neb. "The incidence of tornadoes on the central Plains is slightly higher during La Nina."



There has been one previous study investigating ENSO impacts on tornadoes. An unpublished manuscript by Knowles and Pielke (1993) observed that tornadoes during ENSO cold phase (La Nina) are stronger and remain on the ground longer than their warm phase (El Nino) counterparts. They further showed that there is an increased chance of large tornado outbreaks (40 or more tornadoes associated with a single synoptic system) during ENSO cold phase.

(a coincidence that last year's tornado season was so violent and a La Nina was developing? Probably not, and this year looks to be at least several times worse, it has already had more violent tornadoes than 2005 and 2006 combined, deadliest tornado outbreak in a quarter century (also the most violent tornadoes in one outbreak in that time), a record February tornado outbreak and monthly number of tornadoes)
Member Since: February 22, 2006 Posts: 94 Comments: 32744
351. LakeShadow
4:21 PM GMT on February 25, 2008
Hey folks! How's it going?
We've been white here for a few weeks, last week Tuesday's lake effect event taught us that the 80% frozen over lake can still pack a punch with the snow totals as we got about 13" at my house.

As per tropical discussions, I was wondering what with this moderate-strong La Nina still cranking away, if there was not perhaps some potential for an early start to the tropical season...
La Nina sure messed with the NE winter! What havoc will she reak this spring? And when is she going away????
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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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