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

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

Share this Blog
7
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1905 - 1855

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46Blog Index

1905. Levi32
Out for the evening, have a good night all :)
Member Since: Posts: Comments:
Quoting SouthDadeFish:
PcolaDan, I was talking to a meteorology professor at my school Dr. Willoughby, and we discussed Hurricane Andrew. He informed me that most deaths occurred in Naranja Lakes, where buildings were not up to code. The roofs were not strapped down properly so they flew off, exposing those few who did not evacuate. 95% percent of the people who stayed he said, lived. Those who died were impaled by debris that tore off from houses and were dropped on top of other houses.

Naranja Lakes damage:


That picture sent goose bumps up my spine. I worked down there twice after Andrew with the State of Florida. The damage was incredible. As Skyepony stated "Andrew did a world of good for building codes & enforcement the state over." I remember all the hoopla about it. Andrew was the only event that compared to the tornado of Wichita Falls TX in 1979 that I experienced first hand and also did house to house body searches. (Was lucky, didn't find any.)

The National Weather Service narrative sums up the damage:
%u201CTotal property damage in Wichita Falls was estimated at $400,000,000 (in 1979 dollars). Over 3,000 homes were destroyed and another 1,000 were damaged, and over 1,000 apartment units/ condominiums were destroyed and another 130 damaged. In addition, approximately 140 mobile homes were destroyed, two schools were demolished and 11 others sustained serious damage. Over 100 commercial businesses, some of them large manufacturing concerns, were destroyed. It is estimated that 5,000 families, containing 20,000 residents, were left homeless in Wichita Falls.


Wichita Falls
Member Since: Posts: Comments:
Quoting Levi32:


And why would we....it rocks lol =)



so dos window 7 lol
Member Since: Posts: Comments:
1901. Levi32
Quoting Cane2010:
Hiya, Keeper! Does El Nino continue to fade, levi?


Slowly but surely yes. The central Pacific is continuing to cool and the SOI is peaking strongly positive right now, at least in the dailies, the 30-day moving average will take a little longer to go above zero.

Also, there's still warm subsurface water in the eastern Pacific (Nino 3 region) that is showing up at the surface now, which is stalling the cooling there and making the eastern Pacific now warmer than the central Pacific (Nino 3.4 region). This will delay the cooling in the east for a while, but it's all going to come crashing down during the next 2-3 months.







Member Since: Posts: Comments:
1900. beell
Quoting Levi32:


And why would we....it rocks lol =)


To take advantage of SATA Drive technology. Not very well supported on XP.
Member Since: Posts: Comments:
uuuuhhhh I think I must have missed something.
Member Since: Posts: Comments:
Quoting SouthALWX:

Oh I agree, it's not the one comment that has driven me to consternation, it's the overall theme of the past several posts.


The overall theme is that storm surge is the killer and that too much emphasis is sometimes placed on wind which generally kills less than surge or the aftermath. Carry on.
Member Since: Posts: Comments:
1897. Levi32
Quoting Tazmanian:
no one wants too move a way from window XP lol


And why would we....it rocks lol =)
Member Since: Posts: Comments:
PcolaDan, I was talking to a meteorology professor at my school Dr. Willoughby, and we discussed Hurricane Andrew. He informed me that most deaths occurred in Naranja Lakes, where buildings were not up to code. The roofs were not strapped down properly so they flew off, exposing those few who did not evacuate. 95% percent of the people who stayed he said, lived. Those who died were impaled by debris that tore off from houses and were dropped on top of other houses.

Naranja Lakes damage:
Member Since: Posts: Comments:
Quoting presslord:
...as Ron White says: "It ain't the wind...it's what's in it..."

absolutely. I made that point at the start of this conversation lol
Member Since: Posts: Comments:
no one wants too move a way from window XP lol
Member Since: Posts: Comments:
Quoting PcolaDan:



The wind can kill, but is usually not the main means of death. Hurricane Andrew was a major windstorm. I could not find a breakdown of how the deaths occurred.

from http://www.ncbi.nlm.nih.gov/pubmed/8656186

Hurricane Andrew, a category 4 storm, made landfall in South Florida on August 24, 1992, and caused extensive structural and environmental damage. The Dade County Medical Examiner Department investigated 15 deaths directly related to the storm and another 15 natural deaths indirectly related to the storm. The aftermath of the hurricane continued to create circumstances that lead to 32 accidental deaths, five suicides, and four homicides over the next six months. Traffic fatalities due to uncontrolled intersections accounted for one-third of the post-storm accidental deaths. Dyadic deaths (homicide-suicide) doubled in rate for the six months following the storm. The limited number of direct hurricane deaths is attributed to advance storm warnings, its occurrence on a weekend, the storm's passage through less populated areas of the county, and the relatively modest amount of accompanying rainfall.

Oh I agree, it's not the one comment that has driven me to consternation, it's the overall theme of the past several posts.
Member Since: Posts: Comments:
...as Ron White says: "It ain't the wind...it's what's in it..."
Member Since: August 13, 2007 Posts: 0 Comments: 10484
Quoting PcolaDan:



The wind can kill, but is usually not the main means of death. Hurricane Andrew was a major windstorm. I could not find a breakdown of how the deaths occurred.

from http://www.ncbi.nlm.nih.gov/pubmed/8656186

Hurricane Andrew, a category 4 storm, made landfall in South Florida on August 24, 1992, and caused extensive structural and environmental damage. The Dade County Medical Examiner Department investigated 15 deaths directly related to the storm and another 15 natural deaths indirectly related to the storm. The aftermath of the hurricane continued to create circumstances that lead to 32 accidental deaths, five suicides, and four homicides over the next six months. Traffic fatalities due to uncontrolled intersections accounted for one-third of the post-storm accidental deaths. Dyadic deaths (homicide-suicide) doubled in rate for the six months following the storm. The limited number of direct hurricane deaths is attributed to advance storm warnings, its occurrence on a weekend, the storm's passage through less populated areas of the county, and the relatively modest amount of accompanying rainfall.


Thankyou
Member Since: Posts: Comments:
1889. Skyepony (Mod)
FloridaKestrel~ reinforced concrete roof deck.. that is going all out:)
Member Since: Posts: Comments:
Quoting SouthALWX:

you speak like the wind doesnt and cant kill people. you are misinformed.



The wind can kill, but is usually not the main means of death. Hurricane Andrew was a major windstorm. I could not find a breakdown of how the deaths occurred.

from http://www.ncbi.nlm.nih.gov/pubmed/8656186

Hurricane Andrew, a category 4 storm, made landfall in South Florida on August 24, 1992, and caused extensive structural and environmental damage. The Dade County Medical Examiner Department investigated 15 deaths directly related to the storm and another 15 natural deaths indirectly related to the storm. The aftermath of the hurricane continued to create circumstances that lead to 32 accidental deaths, five suicides, and four homicides over the next six months. Traffic fatalities due to uncontrolled intersections accounted for one-third of the post-storm accidental deaths. Dyadic deaths (homicide-suicide) doubled in rate for the six months following the storm. The limited number of direct hurricane deaths is attributed to advance storm warnings, its occurrence on a weekend, the storm's passage through less populated areas of the county, and the relatively modest amount of accompanying rainfall.
Member Since: Posts: Comments:
I know what your comment said, and I also know how you have been sounding the better part of the past 5 hours. Im not sure why you keep posting statistics that suggest wind isn't hazardous if that's not the point you are trying to make. Also, I still never saw a response to the question pertaining to the tornado intercept vehicles and your assumption that intercepting cat 5 winds would be " no great feat" .... Last I checked they intercepted ef3 and under. thats roughly equivalent to a marginal cat 5 sustained, excluding max gusts.
Member Since: Posts: Comments:
Quoting Patrap:
A hurricane's "hot towers" can increase its intensity by adding power to boost the storm's heat engine. For the first time, research meteorologists have run complex simulations of these phenomena using a very fine temporal resolution. They have combined this new simulation data with satellite observations to study the innerworking of the "hot towers" in never-before-seen detail.



very cool vid!
Member Since: August 11, 2008 Posts: 3 Comments: 1596
Quoting KEEPEROFTHEGATE:


that earthquake is at the location of axial volcano and kog i swear when you post the whole earth eq's it freaks me out me at first because it looks bigger than it is! but i'm getting use to it.

Member Since: August 11, 2008 Posts: 3 Comments: 1596
IE 8 is Rip un less IE 9 makes a big come back wish i cant wait too start testing but in tell then am staying with firefox
Member Since: Posts: Comments:
I like it a lot
Member Since: August 13, 2007 Posts: 0 Comments: 10484
2005:



2010:

Member Since: Posts: Comments:
am runing firefox 3.6.3
Member Since: Posts: Comments:
1880. flsky
Quoting Bordonaro:

I downloaded it as an experiment about 3 wks ago, and I got rid of IE 8 the next day.


I had A LOT of probs w/IE8. Went back to IE7 and same. I don't know why I left Firefox, but I'm certainly back to it now!
Member Since: Posts: Comments:
1879. Skyepony (Mod)
Quoting FloridaTigers:


Why rip out the screens? Would the hurricane tear it apart anyways? My house was built shortly before Andrew, and was in West Kendall so the damage was no where near as bad as say Cutler Ridge or Countrywalk.


May as well, cat 5 they are coming down anyway. Better then getting slapped by them. Andrew did a world of good for building codes & enforcement the state over. There was 7 inspectors at the time..it figured to 6 mins an inspection (most done in the car), including drive time around Homestead before he hit.

Member Since: Posts: Comments:
Quoting presslord:
alright Bord...you inspired me...RIP IE...now using Firefox...

How do you like Firefox so far Press?
Member Since: August 25, 2009 Posts: 20 Comments: 6785
1877. Levi32
Quoting StormW:


I'm gonna WU email you something. No hurry.


Alright.
Member Since: Posts: Comments:
1875. Patrap
From my early blogging days in 2006,some pics are mine,most are other.The text is from a friend


"I don't think anybody anticipated the breach of the levees."
-President Bush, on "Good Morning America," Sept. 1, 2005,
six days after repeated warnings from experts about the scope of damage expected from Hurricane Katrina

What is not explained by the transcripts is what the White House actually did apart from express concern. Some observers point to the damning fact that Mr Chertoff,
just 12 hours before Katrina struck, went to Atlanta for a bird flu conference.


A DAY before Hurricane Katrina struck President George Bush and his Homeland Security chief,
Michael Chertoff, were warned in a special video briefing that the New Orleans levees
could be breached and if that happened, the consequences would be devastating.
Mr Bush was still on holiday at his ranch in Texas when he received the briefing
from Federal Emergency Management Authority officials. According to a video obtained by the Associated Press,
he did not ask a single question during the briefing. Instead, he assured the officials that the federal government
was ready to move if Katrina caused a breach of the levees.


FF 3.6 the only Browser fitted for wu and the Tropics

Member Since: July 3, 2005 Posts: 423 Comments: 127814
1874. Levi32
Quoting StormW:


Levi,
You gonna be around for a little?


You mean this evening? I'm not sure yet, I may have to leave sometime in the next 15-30 minutes.
Member Since: Posts: Comments:
Quoting presslord:
alright Bord...you inspired me...RIP IE...now using Firefox...


+1
Member Since: June 28, 2006 Posts: 25 Comments: 8306
Quoting SouthALWX:

you speak like the wind doesnt and cant kill people. you are misinformed.


Incorrect. I never said that it doesn't or can't. I did say that more people die after the storm than do too the wind during the storm. Refer to my post you quoted.
Member Since: Posts: Comments:
1870. flsky
Quoting SouthALWX:

you speak like the wind doesnt and cant kill people. you are misinformed.


People certainly do die due to wind, but many, many people die after a storm from accidents with tools, generators, falling items, debris on the ground, etc., etc.
Member Since: Posts: Comments:
1869. Levi32
These are the U.S. summer temperature anomalies during hurricane seasons with significantly above-average hurricane landfalls on the U.S. coastline (I defined "significantly above average" as greater than one standard deviation above the 1948-2009 mean, which constitutes 3 or more hurricane landfalls)



You can see how warm the country is during these years. This is because of a lot of ridging over the CONUS and blocking over SE Canada, which you can see below in the image of 500mb anomalies based on the criteria listed above. This pattern strongly resembles a cold(negative) PDO, which is not surprising. This is a favorable setup for U.S. landfalls as the blocking over SE Canada argues for less of a trough to steer hurricanes away from the coast. The inverted trough-shape of negative anomalies over Florida and the Caribbean represents an area of low pressures, high instability, and low wind shear which is a healthy environment for hurricanes to make an approach to the U.S. coastline. It will be interesting to watch the model battle for this summer's temperatures and see who's right. Hopefully it's the CFS (forecasting a cold summer), but I doubt it.

Member Since: Posts: Comments:
alright Bord...you inspired me...RIP IE...now using Firefox...
Member Since: August 13, 2007 Posts: 0 Comments: 10484
If there was a threat from a foreign country too a 200 mile stretch of US coastal mainland, the military would react and swarm the area. Why not utilize these military assets ahead of a mafor hurricane? How many died in in Katrina again? How many of these lives may have been saved had a substantial military resue and relief operation been staged in the Northern GOMEX 48 hrs prior to landfall?
Member Since: Posts: Comments:
Quoting Skyepony:
I know I'm late jumping in the Cat5 game. Wouldn't play near any possible surge. No thanks to a flag pole. I think over a parking garage I'd prefer a reinforced concrete (preferably poured) house..those ones developers & contractors build for themselves.



Actually, we have such a shelter in our backyard built by my contractor husband last year that masquerades by day as my studio - but doesn't look like a bunker. It's a free-standing, certified Cat5 structure (designed and certified by a prominent structural engineer) built w/ solid, poured concrete block walls w/ a 6" reinforced concrete roof deck over Epicore steel. Grid-tied photovoltaics w/ battery back-up and 600 gallons of rainwater storage. The house is in a non-evacuation zone in Tampa Bay. The contractor's office is located in a flood zone; we need to remain in the area and be up and running ASAP after the storm.
Member Since: Posts: Comments:
Quoting kmanislander:


Hi there,

In my opinion there are several reasons why the flooding experienced with Ivan did not result in multiple drowning deaths. They are as follows.

1. The brunt of the hurricane was experienced during daylight hours. Had the severe flooding occurred at night time many would have been caught by surprise and would likely have been washed out of their homes in the dark. On the Western end of the island where I live the sea came inland around 10 am when we could see the water level rising outside the home. That gave us about one hour warning to get upstairs out of harms way.

2. The island is small and has an average height above sea level of about 5 feet. The water that came inland on one coast drained off on the other side with little to impede the offshore flow.

3. Most importantly, we do not have a continental shelf that piles up the onshore flow that is so catatrophic with storm surge. Most of the water damage was from high wave action driven by wind. As the storm moved away and the wind eased off the water levels receded just as quickly. In fact, as you know the islands are the peak of an underwater mountain with extreme depths close to shore. This mitigates against the kind of surge effect experienced in the GOM where a large continental shelf coupled with landlocked bays serve to force water inland as typical surge.

These Islands have a topography that reacts quite differently to hurricane winds and seas than is the case with a large land mass such as the Gulf coast region with a continental shelf that stretches for over a 100 miles offshore and is relatively shallow compared to the NW caribbean that goes down to over 25,000 feet in our area. Deep water will not allow surge to pile up in the typical manner seen elsewhere. The water comes in and is gone in a matter of four or five hours. It will not sit like it did in New Orleans


This is what I was thinking but wasn't sure. Thanks for confirming my thoughts.
Member Since: Posts: Comments:
1864. KEEPEROFTHEGATE (Mod)
Quoting Cane2010:
Evening.
evening bud
Member Since: July 15, 2006 Posts: 170 Comments: 53553
1863. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 170 Comments: 53553
1861. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 170 Comments: 53553
Quoting iluvjess:
I think more folks die after the storm than there are casualties due to wind.

you speak like the wind doesnt and cant kill people. you are misinformed.
Member Since: Posts: Comments:
Quoting stormwatcherCI:
. The weakening trend was short-lived and Ivan re-strengthened to category 5 for its third and final time when it was about 80 n mi west of Grand Cayman Island. Although Ivan was weakening while the center passed south of Grand Cayman on 12 September, the hurricane still brought sustained winds just below category 5 strength (Table 3) to the island. This resulted in widespread wind damage, and a storm surge that completely over swept the island except for the extreme northeastern portion.I was really surprised after this that we didn't have any deaths from drowning. I live on the southeastern corner of the island and many people had to be rescued from their roof. I wonder if us being basically flat and small helped to prevent long term flooding resulting in drowning deaths. Any opinions on this are appreciated.


Hi there,

In my opinion there are several reasons why the flooding experienced with Ivan did not result in multiple drowning deaths. They are as follows.

1. The brunt of the hurricane was experienced during daylight hours. Had the severe flooding occurred at night time many would have been caught by surprise and would likely have been washed out of their homes in the dark. On the Western end of the island where I live the sea came inland around 10 am when we could see the water level rising outside the home. That gave us about one hour warning to get upstairs out of harms way.

2. The island is small and has an average height above sea level of about 5 feet. The water that came inland on one coast drained off on the other side with little to impede the offshore flow.

3. Most importantly, we do not have a continental shelf that piles up the onshore flow that is so catatrophic with storm surge. Most of the water damage was from high wave action driven by wind. As the storm moved away and the wind eased off the water levels receded just as quickly. In fact, as you know the islands are the peak of an underwater mountain with extreme depths close to shore. This mitigates against the kind of surge effect experienced in the GOM where a large continental shelf coupled with landlocked bays serve to force water inland as typical surge.

These Islands have a topography that reacts quite differently to hurricane winds and seas than is the case with a large land mass such as the Gulf coast region with a continental shelf that stretches for over a 100 miles offshore and is relatively shallow compared to the NW caribbean that goes down to over 25,000 feet in our area. Deep water will not allow surge to pile up in the typical manner seen elsewhere. The water comes in and is gone in a matter of four or five hours. It will not sit like it did in New Orleans


Member Since: Posts: Comments:
1858. Patrap
A hurricane's "hot towers" can increase its intensity by adding power to boost the storm's heat engine. For the first time, research meteorologists have run complex simulations of these phenomena using a very fine temporal resolution. They have combined this new simulation data with satellite observations to study the innerworking of the "hot towers" in never-before-seen detail.

Member Since: July 3, 2005 Posts: 423 Comments: 127814
Quoting stormwatcherCI:
. The weakening trend was short-lived and Ivan re-strengthened to category 5 for its third and final time when it was about 80 n mi west of Grand Cayman Island. Although Ivan was weakening while the center passed south of Grand Cayman on 12 September, the hurricane still brought sustained winds just below category 5 strength (Table 3) to the island. This resulted in widespread wind damage, and a storm surge that completely over swept the island except for the extreme northeastern portion.I was really surprised after this that we didn't have any deaths from drowning. I live on the southeastern corner of the island and many people had to be rescued from their roof. I wonder if us being basically flat and small helped to prevent long term flooding resulting in drowning deaths. Any opinions on this are appreciated.


As a rule, storm surge recedes fairly quickly. Water by it's very nature seeks the lowest point. It will remain in a hollow, sometimes even creating a salt water pond or lake that may never disappear. Island are the top of mountains sticking out of the water in the oceans, and often sandbars close to land (think Gulf Coast barrier islands). The natural tendency of the major portion of islands is to slope outwards towards the sea. Once the tide goes down the water for the most part will go down with it. Plus, much of the surge water may actually pass over a low island and keep on going. On the mainland coastal areas also have this slope towards the sea, but because of landmass, the surge has to actually retreat.
(Geez, I'm on a roll tonight.)
Member Since: Posts: Comments:
Quoting presslord:
yea...I'm just about done with IE...

I downloaded it as an experiment about 3 wks ago, and I got rid of IE 8 the next day.
Member Since: August 25, 2009 Posts: 20 Comments: 6785

Viewing: 1905 - 1855

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46Blog Index

Top of Page

About

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

Local Weather

Overcast
75 °F
Overcast