Global warming and the frequency of intense Atlantic hurricanes: model results

By: Dr. Jeff Masters , 1:37 PM GMT on April 05, 2010

Could global warming increase wind shear over the Atlantic, potentially leading to a decrease in the frequency of Atlantic hurricanes? There is a growing consensus among hurricane scientists that this is indeed quite possible. Two recent studies, by Zhao et al. (2009), "Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50-km Resolution GCM", and by Knutson et al. (2008), "Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", found that global warming might increase wind shear over the Atlantic by the end of the century, resulting in a decrease in the number of Atlantic hurricanes. For example, the second study took 18 relatively coarse (>60 km grid size) models used to formulate the 2007 IPCC climate report, and "downscaled" them using a higher-resolution (18 km grid size) model called ZETAC that was able to successfully simulate the frequencies of hurricanes over the past 50 years. When the 18 km ZETAC model was driven using the climate conditions we expect in 2100, as output by the 18 IPCC models, the authors found that a reduction of Atlantic tropical storms by 27% and hurricanes by 18% by the end of the century resulted. An important reason that their model predicted a decrease in the frequency of Atlantic hurricanes was due to a predicted increase in wind shear. As I explain in my wind shear tutorial, a large change of wind speed with height over a hurricane creates a shearing force that tends to tear the storm apart. The amount of wind shear is critical in determining whether a hurricane can form or survive.


Figure 1. Top: predicted change by 2100 in wind shear (in meters per second per degree C of warming--multiply by two to get mph) as predicted by summing the predictions of 18 climate models. Bottom: The number of models that predict the effect shown in the top image. The dots show the locations where tropical storms formed between 1981-2005. The box indicates a region of frequent hurricane formation where wind shear is not predicted to change much. Image credit: Geophysical Research Letters, "Increased Tropical Atlantic Wind Shear in Model Projections of Global Warming", by Vecchi and Soden, 2007.

Since the Knutson et al. study using the 18 km resolution ZETAC model was not detailed enough to look at what might happen to major Category 3 and stronger hurricanes, a new study using a higher resolution model was needed. This was done by a team of modelers led by Dr. Morris Bender of NOAA's GFDL laboratory, who published their results in Science in February. The authors used the GFDL hurricane model--the model that has been our best-performing operation hurricane track forecasting model over the past five years--to perform their study. The GFDL hurricane model runs at a resolution of 9 km, which is detailed enough to make accurate simulations of major hurricanes. The researchers did a double downscaling study, where they first took the forecast atmospheric and oceanic conditions at generated by the coarse (>60 km grid) IPCC models, used these data to initialize the finer resolution 18 km ZETAC model, then used the output from the ZETAC model to initialize the high-resolution GFDL hurricane model. The final results of this "double downscaling" study suggest that although the total number of hurricanes is expected to decrease by the end of the century, we should expect an increase of 81% in the number of Category 4 and 5 storms in the Atlantic. This trend should not be clearly detectable until about 60 years from now, given a scenario in which CO2 doubles by 2100. The authors say that their model predicts that there should already have been a 20% increase in the number of Category 4 and 5 storms since the 1940s, given the approximate 0.5°C warming of the tropical Atlantic during that period. This trend is too small to be detectable, given the high natural variability and the difficulty we've had accurately measuring the exact strength of intense hurricanes before the 1980s.The region of the Atlantic expected to see the greatest increase in Category 4 and 5 storms by the year 2100 is over the Bahama Islands (Figure 2), since wind shear is not expected to increase in this region, and sea surface temperatures and atmospheric instability are expected to increase there.

The net effect of a decrease in total number of hurricanes but an increase in the strongest hurricanes should cause an increase in U.S. hurricane damages of about 30% by the end of the century, the authors compute, assuming that hurricane damages behave as they did during the past century. Over the past century, Category 4 and 5 hurricanes made up only 6% of all U.S. landfalls, but accounted for 48% of all U.S. damage (if normalized to account for increases in U.S. population and wealth, Pielke et al., 2008.)


Figure 2. Expected change in Atlantic Category 4 and 5 hurricanes per decade expected by the year 2100, according to the Science paper by Bender et al. (2010).

Commentary
These results seem reasonable, since the models in question have been successfully been able to simulate the behavior of hurricanes over the past 50 years. However, the uncertainties are high and lot more research needs to be done before we can be confident of the results. Not all of the IPCC models predict an increase in wind shear over the tropical Atlantic by 2100, so the increase in Category 4 and 5 hurricanes could be much greater. Also, the GFDL model was observed to under-predict the strength of intense hurricanes in the current climate, so it may not be creating enough Category 4 and 5 hurricanes in the future climate of 2100. On the other hand, IPCC models such as the UKMO-HadCM3 predict a very large increase in wind shear, leading to a drastic reduction in all hurricanes in the Atlantic by 2100, including Category 4 and 5 storms. So Category 4 and 5 hurricane frequency could easily be much greater or much less than the 81% increase by 2100 found by Bender et al.

The estimates of a 30% increase in hurricane damages by 2100 may be considerably too low, since this estimate assumes that sea level rise will continue at the same pace as was observed in the 20th century. Sea level rise has accelerated since the 1990s, and it is likely that this century we will see much more than than the 7 inches of global sea level rise that was observed last century. Higher sea level rise rates will sharply increase the damages due to storm surge, which account for a large amount of the damage from intense Category 4 and 5 hurricanes.

Keep in mind that while a 30% in hurricane damage by the end of the century is significant, this will not be the main reason hurricane damages will increase this century. Hurricane damages are currently doubling every ten years, according to Pielke et al., 2008. This is primarily due to the increasing population along the coast and increased wealth of the population. The authors theorize that the Great Miami Hurricane of 1926, a Category 4 monster that made a direct hit on Miami Beach, would have caused about $150 billion in damage had it hit in 2005. By 2015, the authors expect the same hurricane would do $300 billion in damage. This number would increase to $600 billion by 2025 (though I think it is likely that the recent recession may delay this damage total a few years into the future.) It is essential that we limit coastal development in vulnerable coastal areas, particularly along barrier islands, to reduce some of the astronomical price tags hurricanes are going to be causing. Adoption and enforcement of strict building standards is also a must.

The authors of the GFDL hurricane model study have put together a nice web page with links to the paper and some detailed non-technical explanations of the paper.

References
Bender et al., 2010, "Modeled Impact of Anthropogenic Warming on the Frequency of Intense Atlantic Hurricanes", Science, 22 January 2010: Vol. 327. no. 5964, pp. 454 - 458 DOI: 10.1126/science.1180568.

Vecchi, G.A., B.J. Soden, A.T. Wittenberg, I.M. Held, A. Leetmaa, and M.J. Harrison, 2006, "Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing", Nature, 441(7089), 73-76.

Vecchi, G.A., and B.J. Soden, 2007, "Increased Tropical Atlantic Wind Shear in Model Projections of Global Warming", Geophysical Research Letters, 34, L08702, doi:10.1029/2006GL028905, 2007.

Jeff Masters

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Quoting Drakoen:


I was qualifying the argument with the humidity maps; but anyways...

Your storm track maps are more about the A/B high set up and less about wind shear. You said and I quote: "The big reduction is TO THE WEST, where the high shear is." You were most definitely implying the high wind shear was the result of less storm tracks in the Caribbean rather than steering currents during a positive NAO.

Also, i'm not sure what you mean by 5 latitude difference. I meant 10N to 15. Again your map shows below average anomalies were between those latitudes where the IPCC shows an increase in shear. The 200mb wind speeds are not the everything with wind shear which is a difference with height.


I said the reduction is to the west where the shear is, yes, because it is a big factor, but I never said it was the ONLY factor. You know I know that, and I just discussed it in my last response to Skye. It does contribute to the lack of Caribbean and gulf storms. We're not just talking about long-track storms developing west of Africa and getting steered this way and that by the A/B High. You're forgetting all the storms that form west of 60W in the Caribbean, and in the GOM, that threaten the U.S. far more than storms that form farther away. There is an obvious lack of those shown in my track maps as well. That goes to show how conditions are not favorable for a lot of developments in the SW Atlantic and Caribbean during El Ninos, and wind shear is part of that.

As far as the 5-latitude difference, I mean that the IPCC map shows higher shear anomalies beginning at 10N and northward, whereas typical El Ninos have higher-than-normal shear beginning farther north at 15N. I do acknowledge that discrepancy.
Member Since: November 24, 2005 Posts: 635 Comments: 26780
Like I said, 2009-2010 has been the 2005 Hurricane season of earthquakes :P

I love this blog in the "off-season". So much intelligent discussion, so much to learn before the season starts and all the trolls/JFV's come around.
Member Since: May 17, 2009 Posts: 0 Comments: 559
What I want to know is why the 700 mb change in relative humidity is only plotted for the oceans...percent changes of single digits there isn't an impact like it would be over land.

Y'all enjoy. Beyond that, I am too worn out from time off of work to jump into this fray...
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Quoting Levi32:


Drak, I'm not sure what it is I said that you are trying to refute with the entire first part of that post. The humidity images you posted absolutely support my argument. They are textbook El Nino with the added moisture in the central-eastern equatorial Pacific with a dry southwest Atlantic due to high pressure and subsidence of air.

"For your relation with El Nino years and shear, El Nino years don't just favor increased shear in the Caribbean but a positive NAO which would favor tracks further further east anyway. So the reliability on maps such as though alone, I don't see as enough support. The 500mb anomalies over recent El Nino years revealed below average heights over the eastern seaboard which would suggest recurvature."

I have no idea what you're getting at here. Not enough support for what? And again your maps only illustrated what I already said. El Ninos feature a far less number of storms in the Caribbean, gulf, and SW Atlantic with more recurvature. My point was how there is little difference in the eastern Atlantic, where El Ninos actually don't significantly increase the shear. The main effect of El Nino is felt in the southwestern quadrant of the Atlantic, which I keep stressing.

Yes I know there is a 5-degree latitude difference in the wind shear anomalies between my maps and the IPCC's. There is probably something else going on in the models causing that shift southward. Keep in mind what they are forecasting is an El Nino condition of such severity and longevity that we have never before seen. But looking at the big picture, it is amazing how similar it is. Your humidity maps especially are just an awesome illustration of what I am talking about.


I was qualifying the argument with the humidity maps; but anyways...

Your storm track maps are more about the A/B high set up and less about wind shear. You said and I quote: "The big reduction is TO THE WEST, where the high shear is." You were most definitely implying the high wind shear was the result of less storm tracks in the Caribbean rather than steering currents during a positive NAO.

Also, i'm not sure what you mean by 5 latitude difference. I meant 10N to 15N. Again your map shows below average anomalies were between those latitudes where the IPCC shows an increase in shear. The 200mb wind speeds are not the everything with wind shear which is a difference with height.
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Quoting Skyepony:
Drak~ Thanks..

Levi~ It's pretty obvious that shear doesn't increase alot & prevent hurricanes consistently in all El Nino years, as you pointed out..personally I experienced 3 during the El Nino year of 2004. That makes yet one more argument that that those maps doesn't show a permanent super el nino.

Your La Nina vs El Nino maps has much less to do with shear & more to do where the A/B high sets up during each event. Remember 2007 when Felix & the rest went due west, keeping south the strong high.. it's expected & has nothing to do with shear.

As for where the MDR is located it's actually drawn on both those maps as a black rectangle..& is stated as such in the figure description.

I hadn't realized it was an ensemble but my point they don't all agree as much as they could. I've seen different scenarios, some with much more shear or perhaps it was worked out for the projected actual shear unlike this one which is increased shear for each %uFFFDC increase. Long range models are usually not right on. NW passage wasn't suppose to open til 2050 at the earliest by the runs 15yrs ago.


VAbeachhurricanes~ what personal insults? I like Levi. We can have a friendly debate for fun if we want.. Many times we both learn something from it.


"It's pretty obvious that shear doesn't increase alot & prevent hurricanes consistently in all El Nino years, as you pointed out..personally I experienced 3 during the El Nino year of 2004. That makes yet one more argument that that those maps doesn't show a permanent super el nino."

You know quite well 2004 was a central-pacific based Nino that had a special effect on the Atlantic and allowed for an active season and many landfalls. I don't see where that's an argument for the IPCC models not showing a nino. Did you not see the humidity IPCC forecast map posted by Drak? If that's not a textbook El Nino then what is pray tell?

"Your La Nina vs El Nino maps has much less to do with shear & more to do where the A/B high sets up during each event. Remember 2007 when Felix & the rest went due west, keeping south the strong high.. it's expected & has nothing to do with shear."

I also posted a shear map (200mb wind speeds) which showed strong westerly winds over the SW Atlantic associated with El Nino years. You can't say that doesn't have a lot to do with it. It's a combination of many things Skye, not just the A/B high. It's basic logic here. El Ninos promote upward motion in the eastern Pacific, which results in net downward motion over the Caribbean and SW Atlantic, which suppresses convection, and thus, makes it drier, and thus, results in less storms. El Ninos also have lower-than-normal pressures over NW South America which strengthens the Columbian Heat Low, which increases the trade winds over the Caribbean, which disrupts surface convergence, which fizzles many a tropical wave which tries to form a circulation.

Wind shear is a big part of it too, as upward motion and convection over the eastern Pacific cause air in the upper levels to spread outward, eastward over the Atlantic, resulting in more upper-level westerlies associated with a more southerly-positioned subtropical jetstream due to the reversed Walker Circulation.

"As for where the MDR is located it's actually drawn on both those maps as a black rectangle..& is stated as such in the figure description."

Yes a black rectangle that encloses about the same amount of blue as red, and mostly white, which represents no change in shear. Also when talking about the deep tropical breeding grounds as a whole you want to consider the rest of the "full" MDR which includes the Caribbean as well. Storms trying to make it towards the Caribbean or U.S. would weaken due to the higher shear. Besides, I showed you how wind shear doesn't significantly increase in the eastern MDR during El Ninos

"I hadn't realized it was an ensemble but my point they don't all agree as much as they could. I've seen different scenarios, some with much more shear or perhaps it was worked out for the projected actual shear unlike this one which is increased shear for each %uFFFDC increase. Long range models are usually not right on. NW passage wasn't suppose to open til 2050 at the earliest by the runs 15yrs ago."

I know they don't all agree. I'm just saying that everything fed to us by Dr. Masters and the media and everyone else, all the maps I have seen, look very much like the kind of patterns we see during El Ninos. Again, look at Drak's humidity map please. It illustrates my point very well.

Member Since: November 24, 2005 Posts: 635 Comments: 26780
692. indianrivguy 3:44 PM PDT on April 06, 2010
Quoting presslord:
"Sumatra" was my ex wife's name....Can we please refer to it as something else?


almost shot ice tea out my nose



;)
Member Since: January 24, 2007 Posts: 319 Comments: 31956
We would also have to account for the years with the El Nino Modoki, where a west based EL Nino would even reduce shear over the Atlantic and shift tracks more towards the west.
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Quoting twhcracker:


yes but it's so eloquent with all those adverbs and verbs like "erupt" and "congele (sic)" "powerful" and "push". hmmm. wait a minute. maybe its not jeffstradamas but american pie 2

Sometimes we get what seems to be a journalist's translation of meteorology in here...from a number of sources (internal and external). Sounds like they are trying to sell copy...
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Quoting Drakoen:
Levi, the IPCC shows decreases in relative humidity in both the Caribbean, GOM, and the Eastern Pacific, though a great increase in the humidity levels along the equatorial Pacific.


Here's the relative humidity anomalies for the El Nino years you plotted:



For your relation with El Nino years and shear, El Nino years don't just favor increased shear in the Caribbean but a positive NAO which would favor tracks further further east anyway. So the reliability on maps such as though alone, I don't see as enough support. The 500mb anomalies over recent El Nino years revealed below average heights over the eastern seaboard which would suggest recurvature.




Also the concentration of the high shear is in between 10N-15N on the IPCC map above and at those latitudes in the NCEPNCAR reanalysis Eastern Pacific shear is average to below average.



Drak, I'm not sure what it is I said that you are trying to refute with the entire first part of that post. The humidity images you posted absolutely support my argument. They are textbook El Nino with the added moisture in the central-eastern equatorial Pacific with a dry southwest Atlantic due to high pressure and subsidence of air.

"For your relation with El Nino years and shear, El Nino years don't just favor increased shear in the Caribbean but a positive NAO which would favor tracks further further east anyway. So the reliability on maps such as though alone, I don't see as enough support. The 500mb anomalies over recent El Nino years revealed below average heights over the eastern seaboard which would suggest recurvature."

I have no idea what you're getting at here. Not enough support for what? And again your maps only illustrated what I already said. El Ninos feature a far less number of storms in the Caribbean, gulf, and SW Atlantic with more recurvature. My point was how there is little difference in the eastern Atlantic, where El Ninos actually don't significantly increase the shear. The main effect of El Nino is felt in the southwestern quadrant of the Atlantic, which I keep stressing.

Yes I know there is a 5-degree latitude difference in the wind shear anomalies between my maps and the IPCC's. There is probably something else going on in the models causing that shift southward. Keep in mind what they are forecasting is an El Nino condition of such severity and longevity that we have never before seen. But looking at the big picture, it is amazing how similar it is. Your humidity maps especially are just an awesome illustration of what I am talking about.
Member Since: November 24, 2005 Posts: 635 Comments: 26780
Drak~ Thanks..

Levi~ It's pretty obvious that shear doesn't increase alot & prevent hurricanes consistently in all El Nino years, as you pointed out..personally I experienced 3 during the El Nino year of 2004. That makes yet one more argument that that those maps doesn't show a permanent super el nino.

Your La Nina vs El Nino maps has much less to do with shear & more to do where the A/B high sets up during each event. Remember 2007 when Felix & the rest went due west, keeping south the strong high.. it's expected & has nothing to do with shear.

As for where the MDR is located it's actually drawn on both those maps as a black rectangle..& is stated as such in the figure description.

I hadn't realized it was an ensemble but my point they don't all agree as much as they could & they all don't show the same as you stated... I've seen different scenarios, some with much more shear or perhaps it was worked out for the projected actual shear unlike this one which is increased shear for each degree C increase. Long range models are usually not right on. NW passage wasn't suppose to open til 2050 at the earliest by the runs 15yrs ago.


VAbeachhurricanes~ what personal insults? I like Levi. We can have a friendly debate for fun if we want.. Many times we both learn something from it.
Member Since: August 10, 2005 Posts: 365 Comments: 42550
Quoting Jeff9641:


What becuase it's the correct forcast! THunderstorms will erupt over the next several hours in the Plains and then congele into a powerful squall line and push east. Nothing myeterious about this forecast LADY!


yes but it's so eloquent with all those adverbs and verbs like "erupt" and "congele (sic)" "powerful" and "push". hmmm. wait a minute. maybe its not jeffstradamas but american pie 2
Member Since: July 30, 2007 Posts: 6 Comments: 1448
This is the first one to monitor for water level changes: http://www.ndbc.noaa.gov/station_page.php?station=23401

Station 23401 - 600 NM West-Northwest of Phuket, Thailand

So far looks like so:



Disclaimer: These are famous for showing a lot of movement in the 15 second data (red) that was not apparent in the 15 minute data (blue)...movement that may or may not be related to tsunami water levels.
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Quoting atmoaggie:

Not sure WTH this is about, but they do have more "e"s in their name(s), which seems to appeal to you, Presslord.
;-)

i'm not sure the original blogger Presslord quoted knows what it's about either... ;P
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Quoting presslord:
"Sumatra" was my ex wife's name....Can we please refer to it as something else?


almost shot ice tea out my nose
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ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES AT FORECAST POINTS
WITHIN THE WARNING AND WATCH AREAS ARE GIVEN BELOW. ACTUAL
ARRIVAL TIMES MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE
LARGEST. A TSUNAMI IS A SERIES OF WAVES AND THE TIME BETWEEN
SUCCESSIVE WAVES CAN BE FIVE MINUTES TO ONE HOUR.

LOCATION FORECAST POINT COORDINATES ARRIVAL TIME
-------------------------------- ------------ ------------
INDONESIA SIMEULUE 2.5N 96.0E 2244Z 06 APR
BELAWAN 3.8N 98.8E 0237Z 07 APR

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Quoting Levi32:
Dolly's rapid intensification phase had both a beginning and an end while she was still over water. Don't forget she did weaken before landfall, although some of it was due to dry continental air entrainment and slow movement close to the coast. She was not intensifying coming ashore. The radar loops posted by Indianriver show that clearly. Texas is actually lucky that she did stay over water longer than was thought she would at the time.



It sucked the dry air in and it disrupted the eye wall, none the less, I think they are lucky it came ashore when it did. There is no guarantee that the disruption would have continued over the warm water.
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"Sumatra" was my ex wife's name....Can we please refer to it as something else?
Member Since: August 13, 2007 Posts: 0 Comments: 10538
nobody likes a smart aleck, atmo ; )
Member Since: August 13, 2007 Posts: 0 Comments: 10538
Message indian.2010.04.06.222245
Tsunami Information Earthquake Information
Message Time: 06 Apr 2010 22:22 UTC
Message Num: 001
Message Text: click to read
Message Type: a Local Tsunami Watch is in Effect
Warning: None
Watch: INDONESIA
ETAs / Obs: ETAs
Origin Time: 06 Apr 2010 22:15 UTC
Magnitude: 7.5 Mwp (reviewed by PTWC)
Latitude: 2.2° N
Longitude: 97.1° E
Depth: 50 km (31.1 mi)
Location: Northern Sumatra Indonesia
More Info.: updated earthquake information from the USGS NEIC

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Quoting presslord:
BHy what meeasure, exactly, is the Teabagger Movement bigger than the democratic Party?

Not sure WTH this is about, but they do have more "e"s in their name(s), which seems to appeal to you, Presslord.
;-)
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Levi, the IPCC shows decreases in relative humidity in both the Caribbean, GOM, and the Eastern Pacific, though a great increase in the humidity levels along the equatorial Pacific.


Here's the relative humidity anomalies for the El Nino years you plotted:



For your relation with El Nino years and shear, El Nino years don't just favor increased shear in the Caribbean but a positive NAO which would favor tracks further further east anyway. So the reliability on maps such as though alone, I don't see as enough support. The 500mb anomalies over recent El Nino years revealed below average heights over the eastern seaboard which would suggest recurvature.




Also the concentration of the high shear is in between 10N-15N on the IPCC map above and at those latitudes in the NCEPNCAR reanalysis Eastern Pacific shear is average to below average.

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Tsunami warning?
Member Since: August 13, 2007 Posts: 0 Comments: 10538
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Dolly's rapid intensification phase had both a beginning and an end while she was still over water. Don't forget she did weaken before landfall, although some of it was due to dry continental air entrainment and slow movement close to the coast. She was not intensifying coming ashore. The radar loops posted by Indianriver show that clearly. Texas is actually lucky that she did stay over water longer than was thought she would at the time.

Member Since: November 24, 2005 Posts: 635 Comments: 26780
7.8 quake in Sumatra.....had a feeling the dozens of little ones in the area yesterday was not a good sign.

Member Since: November 24, 2005 Posts: 635 Comments: 26780
Quoting hydrus:
Dolly was organizing while over the G.O.M. South Texas took a pretty good hit, but they were fortunate.


I agree.. same with Humberto. I was pretty amazed watching it live.
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By what meeasure, exactly, is the Teabagger Movement bigger than the Democratic Party?
Member Since: August 13, 2007 Posts: 0 Comments: 10538
Quoting indianrivguy:
Dolly closer


landfall

Dolly was organizing while over the G.O.M. South Texas took a pretty good hit, but they were fortunate.
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Dolly closer


landfall



Relative velocity at landfall



I have Humberto too but it's been covered
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Tune to "Listen"

KS Topeka WXK91 162.475



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Dolly

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674. Inyo
wow, slight chance of thunderstorms right up to here in Vermont. Not normal for April in this part of the world! I wonder if this means there will be lots of thunderstorms up this way later in the year.
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As per the article…Rapid intensification of Hurricane Humberto:



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MESOSCALE DISCUSSION 0272
NWS STORM PREDICTION CENTER NORMAN OK
0455 PM CDT TUE APR 06 2010

AREAS AFFECTED...NERN IA...SRN WI...FAR NRN IL

CONCERNING...TORNADO WATCH 57...

VALID 062155Z - 062300Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 57 CONTINUES.

A SEVERE TSTM WATCH WILL LIKELY BE ISSUED SHORTLY FOR AREAS N/NE OF
WW 57.

AS OF 2150Z...A PAIR OF SUPERCELLS WERE LOCATED FROM GRUNDY TO
BUCHANAN COUNTIES IN IA ALONG THE NRN TIER OF WW 57. SUBJECTIVE
SURFACE ANALYSIS PLACED TRIPLE POINT CYCLONE NEAR DSM...WITH
WEST-EAST ORIENTED WARM FRONT EXTENDING TO ALONG THE IL/WI BORDER.
CONVERGENCE AND LOW-LEVEL WARM THETA-E ADVECTION WITHIN THE FRONTAL
ZONE SHOULD SUPPORT ADDITIONAL TSTM DEVELOPMENT AND/OR PROPAGATION
E/NEWD OUTSIDE OF WW 57 IN NERN IA AND SRN WI. ELEVATED SUPERCELLS
WITH SEVERE HAIL WILL BE THE PRIMARY THREAT...BUT AREAS ALONG THE
IMMEDIATE WARM FRONT WILL BE MONITORED FOR A POSSIBLE TORNADO WATCH
LATER THIS EVENING.

..GRAMS.. 04/06/2010


ATTN...WFO...LOT...MKX...DVN...ARX...DMX...

LAT...LON 42609287 43149249 43599127 43638934 43488795 42868774
42378786 42278928 42159102 41969221 41999278 42609287
Member Since: June 28, 2006 Posts: 25 Comments: 8516
Levi and Skye, kudos for an interesting and respectful discussion, despite the one post to the contrary, and thanks for a presentation of data along with YOUR interpretion of the data. Reading the copy/pastes of others can be educational but it's boring as hell...
Member Since: February 11, 2010 Posts: 3 Comments: 968
Hurricane Dolly

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Quoting CycloneOz:


From the article: "Without an accurate intensity forecast, a storm near the coast that rapidly intensifies into a major hurricane and moves inland would put residents in coastal communities at grave risk even when the forecast of the path of the storm is accurate."

Hurricane Dolly in a nutshell (except for being a major hurricane.) Caught everyone by surprise!
If Dolly had slowed down and been over the water another day, south Texas would have been hit by a strong cat-3 or a weak-4...Just my harmless opinion.
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Quoting FFtrombi:
Levi32, most models show el nino, because that's what the models say will happen. The models are modeling the avg climate @ 2100, which will probably (again according to the models) have more years of el nino than la nina, like we have seen recently.

Now I realise from reading your posts that you are a big fan of the PDO, which you believe will now go negative for the next 30 years. 2010 -> 2040 cold, 2040-> 2070 warm, 2070 -> 2100 cold, 2100 -> warm.. So maybe the models are picking up a likely warm pdo around 2100.


Except that they show a continuous warming trend, uninterrupted right through 2100. The models have never before encountered a cold PDO cycle. The last one ended in 1977. So the world as the models know it is a world with a warm PDO, and they have not seen anything else before in their input. It's not surprising to see them forecasting a continuation of current trends.

Besides (and this is for everyone to ponder), think about our U.S. climate models like the CFS. They are mainly reactionary....if you notice the CFS is always last to pickup on changes in the ENSO. In other words it will nearly never forecast something that goes against persistence and the current trends. The event has to be already occurring for the model to even have a clue. So this adds to the idea that the models could be reacting in a big way to what they know, which isn't much, about our current climate. The IPCC projections are nothing but an extrapolation line of the current warming trend over the last 30 years. If we get a 10-year period of cooling, watch the models panic.
Member Since: November 24, 2005 Posts: 635 Comments: 26780
000
SXUS73 KIND 062042
RERIND

RECORD EVENT REPORT
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
0438 PM EDT TUE APR 06 2010

...RECORD HIGH TEMPERATURE SET AT INDIANAPOLIS IN...

A RECORD HIGH TEMPERATURE OF 83 DEGREES WAS SET AT INDIANAPOLIS
INDIANA TODAY. THIS BREAKS THE OLD RECORD OF 82 SET IN 1929.


NWS
Member Since: June 28, 2006 Posts: 25 Comments: 8516
Quoting GeoffreyWPB:
Hurricane Intensity Still Stymies Forecasters


From the article: "Without an accurate intensity forecast, a storm near the coast that rapidly intensifies into a major hurricane and moves inland would put residents in coastal communities at grave risk even when the forecast of the path of the storm is accurate."

Hurricane Dolly
in a nutshell (except for being a major hurricane.) Caught everyone by surprise!
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Levi32, most models show el nino, because that's what the models say will happen. The models are modeling the avg climate @ 2100, which will probably (again according to the models) have more years of el nino than la nina, like we have seen recently.

Now I realise from reading your posts that you are a big fan of the PDO, which you believe will now go negative for the next 30 years. 2010 -> 2040 cold, 2040-> 2070 warm, 2070 -> 2100 cold, 2100 -> warm.. So maybe the models are picking up a likely warm pdo around 2100.
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Is that a Bermuda High cranking just off FL/GA?

If it is, then that's a bad place for it to be come hurricane season.

Maybe it will slide more easterly so that a channel opens up between it and the CONUS (like last year?)
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A sad story: Link
Member Since: July 7, 2005 Posts: 257 Comments: 21376
Quoting Levi32:


Skye, I said every model projection I've seen, and that map is one of them. I don't care about one ensemble member going against the crowd. Obviously not every single dang computer is going to see the same thing. I'm saying every map, every mean ensemble prediction, every IPCC projection that I have seen presented to us in the public, looks like El Nino. Pat posted precipitation forecasts from the IPCC a couple weeks back. It had increased precipitation over the eastern Pacific and a very much drier Caribbean (think this winter....El Nino...means dry).

And Skye, come on, all the forecasted decreases in shear near the MDR are below what, 8-10N? Lol, hurricanes don't develop that far south Skye. The majority of that map between 10-20N and 20-90W shows increased shear.

Now there is no reanalysis site readily available to the public where you can plot historical wind shear between 200 and 850mb, but we know that a great majority of all wind shear in the Atlantic is caused by upper-level winds at 200mb. Take a look at what the 200mb wind speeds look like during El Ninos during the hurricane season.



Check out the blue in the eastern MDR, meaning weaker upper-level winds, which usually means less shear. I checked the lower levels, and 500mb also shows weaker winds, and so does 850mb. That means that trade winds are slower too. All that means conditions are actually near normal or a little bit more favorable atmospherically for Atlantic hurricanes in the eastern MDR during El Ninos! Oh and also look at all the higher shear north of 15N in the eastern Pacific during El Ninos, which I already explained about to Jeff above. That's not even all hostile shear.

And to prove where the increases in shear are, let's examine hurricane tracks of all observed El Nino years and La Nina years. Notice that there is little difference in the number of Cape Verde tracks in the eastern Atlantic. The big reduction is TO THE WEST, where the high shear is. Now look at the Dr's model map again Skye, and tell me where it differs.

La Nina:



El Nino Hurricane Tracks:




Very nice illustration Levi, very well done! The maps alone tell everything. El-Nino storms track more to the east and La-Nina storms track more west. Great post Levi!!
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Quoting Skyepony:


You don't usually hear people say that, just articles funded by anticlimate saying more hurricanes is bogus.. AMS, NOVA & many other good sources has been pretty open & loud on the subject..

As for the main point I don't see..it's gibberish only to confuse & cause statements like the world is getting colder & that makes me want to drink a glacier.. lets review..

You ask & state...explain to me why every single model projection I see for GW looks like a perfect representation of a permanent El Nino? This map fits beautifully with their super-nino theory though.
Lets look at that map..

Top one is forecasted shear in a warmer world.. if this was a representation of super-el ni%uFFFDo why is shear reduced or normal for the most the MDR in the Atlantic & increased in the EPAC?? This is the exact opposite of El Nino.. Lets just assume your eyes glazed over cause it was a GW map & you took it for hot & cold anomalies..why is the EPAC over the equator..blue for a super el nino?

The bottom map is the actual # of models that forecast this senerio..so right before your eyes your seeing not all 18 models are predicting this or the same thing for that matter & still you state..every single model I've seen... Your too good at reading graphs & maps to ask such a question..


Skye, I said every model projection I've seen, and that map is one of them. I don't care about one ensemble member going against the crowd. Obviously not every single dang computer is going to see the same thing. I'm saying every map, every mean ensemble prediction, every IPCC projection that I have seen presented to us in the public, looks like El Nino. Pat posted precipitation forecasts from the IPCC a couple weeks back. It had increased precipitation over the eastern Pacific and a very much drier Caribbean (think this winter....El Nino...means dry).

And Skye, come on, all the forecasted decreases in shear near the MDR are below what, 8-10N? Lol, hurricanes don't develop that far south Skye. The majority of that map between 10-20N and 20-90W shows increased shear.

Now there is no reanalysis site readily available to the public where you can plot historical wind shear between 200 and 850mb, but we know that a great majority of all wind shear in the Atlantic is caused by upper-level winds at 200mb. Take a look at what the 200mb wind speeds look like during El Ninos during the hurricane season.

200mb Wind Speed anomalies for June-November of all El Nino years:


Check out the blue in the eastern MDR, meaning weaker upper-level winds, which usually means less shear. I checked the lower levels, and 500mb also shows weaker winds, and so does 850mb. That means that trade winds are slower too. All that means conditions are actually near normal or a little bit more favorable atmospherically for Atlantic hurricanes in the eastern MDR during El Ninos! Notice all the increased westerlies caused by El Nino are to the west, over the Caribbean and along the U.S. coastline. Oh and also look at all the higher shear north of 15N in the eastern Pacific during El Ninos, which I already explained about to Jeff above. That's not even all hostile shear, but it's there, just like on the model map.

And to prove where the increases in shear are, let's examine hurricane tracks of all observed El Nino years and La Nina years. Notice that there is little difference in the number of Cape Verde tracks in the eastern Atlantic. The big reduction is TO THE WEST, where the high shear is. Now look at the Dr's model map again Skye, and tell me where it differs.

La Nina Hurricane Tracks:



El Nino Hurricane Tracks:


Member Since: November 24, 2005 Posts: 635 Comments: 26780
Quoting Jeff9641:


I bet the storm chasers are out in force today in Eastern Kansas today.


oh I would imagine
Member Since: June 28, 2006 Posts: 25 Comments: 8516
Quoting Skyepony:


You don't usually hear people say that, just articles funded by anticlimate saying more hurricanes is bogus.. AMS, NOVA & many other good sources has been pretty open & loud on the subject..

As for the main point I don't see..it's gibberish only to confuse & cause statements like the world is getting colder & that makes me want to drink a glacier.. lets review..

You ask & state...explain to me why every single model projection I see for GW looks like a perfect representation of a permanent El Nino? This map fits beautifully with their super-nino theory though.
Lets look at that map..

Top one is forecasted shear in a warmer world.. if this was a representation of super-el niño why is shear reduced or normal for the most the MDR in the Atlantic & increased in the EPAC?? This is the exact opposite of El Nino.. Lets just assume your eyes glazed over cause it was a GW map & you took it for hot & cold anomalies..why is the EPAC over the equator..blue for a super el nino?

The bottom map is the actual # of models that forecast this senerio..so right before your eyes your seeing not all 18 models are predicting this or the same thing for that matter & still you state..every single model I've seen... Your too good at reading graphs & maps to ask such a question..


Forgot you were perfect... its just his theory by looking at the damn map, why do you have shoot him down with personal insults... real mature
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Quoting winter123:
The nasty cell from earlier died crossing Lake Erie.
i'd say it died smashing into NY...
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Quoting tornadodude:


I bet the storm chasers are out in force today in Eastern Kansas today.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Member Since: June 28, 2006 Posts: 25 Comments: 8516

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Dr. Masters (r) co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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