"Flee Ike or Face Certain Death"
This is what is being told to residents of Galveston Texas and surrounding areas. I don't know if that is strictly true or not, but it is close enough that you should listen. Or put it this way: If you stay, and you are wrong, those last few minutes as you are being swept out to sea in the crumbling, tumbling remains of your house, unable to distinguish between sea and sky, choking on the salt water and being battered by debris, will be very, very embarrassing. Seriously. Go. Now.
Having said that, I want to make a few notes on what is true and not true about hurricanes, as we are already seeing stupid reporting and stupid government officials clogging our airwaves. For example, an elected official (a Republican) in Texas just now on MSNBC said "This storm is a different kind of storm. For this storm, we are worried about the storm flood."
Well ... du .. fucking ...uh, lady. The number one and two problems in all hurricanes are the storm surge coming in and the rainfall related floods that occur during and for hours or days after the storm. That. Is. What. Hurricanes. Do. The third biggest problem may be the tornadoes, depending on the storm, and of course, the 90 mile an hour winds for an hour or two are a bad thing too. But the storm surge is what makes people say, with more reason than it might sound, "Flee now or you will all die!"
One of the reasons why people are stupid about hurricanes is that for the last eight years we've had a Republican administration (and prior to that a Republican legislature to varying degrees) which has been doing all it can to keep people stupid about science. Science is the secular devil, the teacher of things our kids should not know (about or how to do). Science is the antiChrist. Knowledge of science may lead to important conclusions such as how the Energy Companies are screwing us, or how "Clean Energy Brought to you from Canada by the song Funky Town" will just produce more nuclear waste, and so on.
This stupidity is what led the Bush administration to actually say "Katriana, the hurricane, did not flood New Orleans. That was rain that flooded New Orleans." ... and do you know, there are still people walking around saying that. Uffda...
To a Republican, Science is bad.
(If you want to know how and why this affects our knowledge of hurricanes, as well as how they are reported and dealt with by the government, look at my review of Chris Mooney's book, then get the book and read it. )
In New Orleans, when Gustav was blowing in, there was great confusion among the MSNBC reporters about concepts such as "Levee" (or Dike), "overtopping" and "breaching". At one point I had the distinct impression that the reporters had the sense that overtopping and breaching were not the same thing, but did not know what the difference is. Breaching is, of course, when the levee breaks and simply is not holding back the water any more (in one or more spots), while overtopping is when the water being held back goes up too high and goes over the top. This is not difficult.
In the case of Gustav, the water was just high enough to lap at but not pour over the top of some levees, but the waves and spray (which is considerable in a hurricane) was washing over the levees. No breaching, no overtopping, but some flooding.
So, how high is the water going to go in Galveston, and why? From the point of view of a particular house, person, piece of land, whatever, in the vicinity, there are several factors that are going to determine whether or not the ocean comes to get you, and how high it will be when it gets there. But just to be clear, having the ocean show up in your living room is not necessarily such a bad thing. The bad thing happens when the ocean leaves. But we'll get to that.
The first thing that matters is the tide. A lot of my readers (six out of the 11) are midwestern, so it is possible that you've never seen the tide. This is where the ocean ... the surface of the ocean ... goes up and down and up and down. Each day. Twice up, twice down, almost exactly every 24 hours (but not exactly, so the time of the high and low tides shifts daily). In the Bay of Fundy, the total vertical distance is between about 35 and 40 feet, if memory serves. think about that for a second. If you are in a house, go outside. Look at the house. How tall is it? If it is a regular house, there is good chance that you are looking at the height of the tide in the Bay of Fundy, more or less. Wow.
I don't know what the tide in Galveston is, but down in the Gulf of Mexico, the tides are generally only a few feet. Maybe five tops.
So if the tide is high when the storm comes in, that is worse than if it is low.
Then there is the storm surge. The storm surge has two componants. First, a hurricane is a low pressure area, so low that the water rises up beneath it. Quite literally, the sea at this point is not as pushed down, or compressed, by the air above it so it gets bigger. Like unsqueezing a pillow. The second and typically larger factor is the wind. The front right quadrant of an Atlantic Hurricane is pushing the water forward, and has been doing this for days. Higher than average waters can be driven towards land in advance of the hurricane, and by the time the strongest winds, perpendicular to the coast, nearest the lowest pressure (around the eye), arrive at the shoreline, you can get five, ten, even 20 feet of extra ocean.
And that is on top of the tide if the tide is high.
Then you have the waves. The waves are important because they are big and they are many. Before and after the main part of the hurricane comes through, the waves are big. I remember the waves of Hurricane Bob on Gloucester. These waves were easily 30 feet high on top of the tide. I remember standing there on shore lookng UP at these waves which would then crash on the rocky shore and send spray seemingly to the clouds, and thinking, "What am I doing here ... If the average wave is this big, what happens when a really big one comes along...." (.. back in car ... drive to high ground .. )
And that was 24 hours after the eye had passed, and the sky was blue.
Right in the middle of a Category 3 or more storm (and Ike may be Cat 3 when it hits), where the wind is at its maximum and the pressure near its minimum, the distinction between the sea and the sky is vague. What would normally be a visible plane with some spray coming off now and then on white caps is a several meter thick zone of water and air mixed. This zone actually comes inland with the storm. The stuff one might think of as rain falling on you when you area a mile or two from the sea tastes like salt, becauase it is actually ocean spray. Right near the sea, upland areas that may have been normally protected all the time from sea spray get their first in a century (or so) dose of salt water. I've seen this on Cape Cod, where over large areas inland there are actually dead trees killed by the salt spray (which floods the land) from a hurricane.
The next factor, and the one that may make the biggest life or death difference in this case, is shoreline configuration. Any place that channels water into smaller areas as you head inland (like the bay at Galveston/Houston) will raise the water. A mile wide inlet that narrows down to a quarter of a mile with a ten foot storm surge will potentially produce a forty foot flood.
All these factors together were important in a storm that came to Galvaston in 1900. It is called the 1900 storm. The existence of hurricanes, at that time, was not fully appreciated or understood in the same universal way it is now. This is one of the storms that told people that living near the shore in low lying areas is potentially dangerous. (But did they listen? No, of course they did not listen..)
At that time, Galveston was under ten feet above sea level, and the storm surge was more than 15 feet. The ocean simply came and took the town away. About 8,000 people died.
Today, Galveston has been built to withstand a storm surge. The city was raised five or ten feet (depending) and a sea wall should stop a 17 foot storm surge.
Unfortunately, the expected storm surge is as much as 20 feet.
Everyone is pretty much getting out of Galveston. But my understanding is that there is a jail with about 1,000 prisoners that might not be evacuated.
So, as you can see, despite the senseless yammering of the Republcans, Hurricane Ike is pretty much a typical killer hurricane.
Now, you are anxious to know why the ocean arriving in your living room is not as bad as when it leaves.
Two reasons: First, it will go more quickly. It will come in slowly because of the back pressure from the land it is over taking. It may loosten stuff up, knock stuff over, make a mess, kill you, and all that bad stuff. But when it leaves, it will leave more quickly with less friction holding it back and it will take whatever is loose with it.
The second reasons pertains to barrier islands. When the sea comes in, it may clog the usual outlet along a barrier island (if indeed there is much of an outlet ... human development often closes the outlets off or limits their usefulness). Then, when the water goes out again, it will find a new outlet.
Any one part of a barrier island may be totally washed away into the sea. Any buildings standing there may become incorporated, at depth, into the barrier island, or into the sand sheet off shore.
The city of Galvaston, of coruse, is built entirely on a barrier island. Like this:
Way to go city planers of Galveston.
Run away.
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Everyone living in the area should leave now. Anyone choosing to stay to face Ike is digging his/her own grave.
If Hurricanes are Acts of God then the revelation is
bUSh hurt Iraq, God hurt US.
1991 George HW bUSh invaded Iraq
1992 Hurricane Andrew.
2003-present George W bUSh invaded/occupied Iraq
2004 Charley, Frances, Ivan, Jeanne.
2005 Katrina, Rita.
2006 Alberto, Beryl, Chris, Florence.
2007 Dean, Erin.
2008 Fay, Gustav, Ike, ..., ...�
Way to go city planers of Galveston.
Galveston developed around a natural harbor, as part of the cotton economy of the Gulf Coast, and like most other cities in Texas, was not planned. Jean Lafitte had a pirate kingdom there (Aarghh!), and it was home to the first medical school in Texas (the original building "Old Red" still stands, and survived the 1900 hurricane). In Eric Larson's book Isaac's Storm, the claim is made that, if not for the 1900 hurricane, Galveston, rather than Houston, would have been the most important center of commerce in Texas.
Ike will be devastating in any case- many of the people who live in Galveston and surrounding coastal communities are already socioeconomically disadvantaged, and they will lose almost everything and be displaced from their homes and social support. Also, Galveston has several hospitals and clinics, including a burn center, which serve the indigent, as well as the prison population, in South and East Texas. Houston, also in the path of Ike, has most of the other main trauma centers and charity hospitals. Storm surge in Galveston as of 1 hour ago already looks pretty bad-the sea wall will hold, but there's a lot not protected by it.
I think I understand what that repub was saying;
This storm is a different kind of storm than Katrina because this is hitting us and not them. For this storm we are worried about storm flood that affects rich people as opposed to that which affects poor people.
Galveston is almost completely underwater at this point. Flooding of the seawall began early this morning, this video is from noon [url]http://www.khou.com/video/news-index.html?nvid=282162[/url].
This is a worst case scenario for Houston just as Allison was 25 years ago as the surge is projected to travel directly into the bay and up the Houston ship channel.
Thoughts to everyone down there and especially to the rescuers (former Texas Task Force 1 member here) who are going to have to risk their lives saving those who decided to ignore the evacuation orders.
As of now Emergency vehicle have pulled off of the road as sustained winds are reaching 50 mph. It is unfortunate that the last major storm of this kind to hit Houston was 25 years ago, the population has doubled and almost a generation of people have no clue of the magnitude of a 20' storm surge. The integrated kinetic energy of this storm (much better measurement than the category system) is 5.2, Katrina was 5.1 upon landfall so this is a major water event.
Good luck to those still around the Texas coast.
Good information overall, but you're underplaying the winds a bit - they don't just move water. Hurricane winds are often like a slightly dampened tornado - stuff is being thrown about at high speeds (eg, wooden planks), trees tend to fall on stuff like houses and electric wires (think of their branches/leaves like one giant sail), and roofs may fly away (most roofs are built like a very basic airfoil in shape, but without the proper supports to keep it firmly down).
The winds and pressure can also affect lakes just like the ocean, producing massive waves, movements, and other undesirable effects (that whoever's living by one prolly hasn't thought about).
"The first thing that matters is the tide." In fact, tides in the Gulf of Mexico don't follow the "official rules". There's generally only one tide per day, due to the complex way that the geography of the Gulf, with its outlets to the Atlantic between Florida, Cuba, and the Yucatan Peninsula, interacts with the gravitational pull of the moon. The result is that in Galveston the tide is only 12 to 18 inches. If you go to the beach there and stay for less than six hours you'll be hard pressed to tell if the tide is going out or coming in.
The second thing to keep in mind for Gulf hurricanes is that because the Gulf is much smaller than the Atlantic or Pacific oceans, there isn't much "fetch" to permit really big waves to build up, although 60-footers have been recorded out in the center. But more important is that the water is very shallow for a long way out from the shore. It is physically impossible for waves to be more than twice the height of the still water depth. So any large Gulf surf breaks very far out from shore. There may be as many as 5 or 6 breaking zones over offshore sand bars before the waves get to the beach.
This leaves only the storm surge itself to worry about. But that's enough. The Galveston seawall is 17 miles long, but water has no problem flowing around the ends and flooding in from the inland, harbor and bay sides of the city. Which is exactly what it did: the historic Strand district near the harbor was just about the first area to flood.
The question you have to have considered if you were foolish enough to ignore the evacuation orders, is whether you have a third floor go to when the surge comes up past the second floor of your structure, and whether it will withstand the force of the water flowing around those lower stories, which is thousands of times more powerful than than the wind roaring overhead. I wouldn't want to be in your house with you when it tips over and starts floating downstream with the receding floods, crashing and splintering into the rest of the flotsam and jetsam.
Good point about the waves, but it is not entirely a matter of fetch, but also currents and overall shape of the coast line. But yes, a small hurricane in the North Atlantic can make much bigger wave than a larger storm in the gulf!
dreikin: Not really, if you count the dead. Most of the dead are from the floods. The winds do of course make a big mess as I've noted, of course.
Hey there, Greg! Terri (the Bay of Fundy blogger) here on the east coast of Canada. Interesting article about Hurricanes - their variety & effects - and interesting analogy to the Bay of Fundy.
Our tides are indeed in the 45 foot range but thankfully the tides take about 6 hr and 13 min to come in then 6 hr 13 to go out so we never get the big wall of water thing. One of the interesting things about the Bay of Fundy that your readers may not know is that our low tide line is about 3 miles from where anyone lives; we give this pile of water a wide, wide berth for many of the reasons indicated in your post.
And, by the way, we also get the tail end of your U.S. hurricanes & tropical storms here on the upper east coast...Bay of Fundy folk still talk about the Saxby Gale in the 1860s that blew our tall ships dozens of miles up over land and into farmers' fields.
As we all become more urbanized & less connected to nature, I think we could all do with a healthier respect for such natural phenomena as tides, storm surges, hurricanes and storms. thanks for raising the issue and generating discussion on the topic.
Best regards, Terri
Terri, you Fundy coast people were lucky to have missed Hurricane Juan - I believe at one point there was a chance it would track up Fundy. Instead it did a devastating blow through Halifax (it was a weak Cat.2 when it hit the Harbour) and surrounding areas. I still have blow-downs in my bit of woods, and so does everyone else in the area - there was just too much to ever clean it all up, and trees weakened then are still falling over every time we get a stiff breeze.
People in hurricane land (the gulf, southeast US) have hurricanes now and then, but you can live in Georgia or Alabama a long time before you experience one. But if you live on Campobello Island, Eastport or Boston, you get to experience a few or even several nor' easters per year. Those are like mild hurricanes that can stay around for days and during the right time of year the rain falls as snow. So when a hurricane comes along, the infrastructure is literally hardened against it already to some degree. Typically, in my experience, the houses in New England and E. Canada can weather these storms very well (as long as the coast stays put, as it has not done, say, on Cape Cod last few years). The boats, of course, sometimes want to go shopping at the local mall or visit their friends in some pond somewhere.
I'm not sure you can blame city planners for the problem, Greg. This sounds trite, but really, it's the system. Coastal municipalities are inclined to build, because revenue from real estate taxes fuels their growth. There is greater incentive to build on barrier islands, because real estate taxes are higher.
But the burden of reconstruction is through FEMA. Its federal money. So, essentially, there is no disincentive for city planners to build houses on the sand. This is a problem for many coastal communities.
Peter: I agree. I was more or less being sarcastic. Galveston was totally destroyed by a hurricane, and completely rebuilt with the idea that it could survive the next hurricane. So far, remarkably, that has worked pretty well. But overall we now know that building on barrier islands or in similar settings is a risky thing to do, which is why so many such terrains are off limits to construction along the Atlantic coast of the US and other places. I would presume so in TX as well.
The point is we never plan and never learn from experience, partly because we overestimate our successes.
Bee, you have my sympathies. I was in Halifax eight years ago and again last year. I saw what Juan did to the Public Gardens. Ouch.
Galveston got hammered, especially the part beyond the seawall (e.g. Surfside). Thousands of people in Galveston did not evacuate (those in Houston itself were told not to), and many are missing. There are boats in parking lots, downed trees, a glass storm in downtown Houston, etc. etc. The coastal communities of eastern Texas and western Louisiana are not populated by wealthy people, contrary to what the eddie-ot wrote above. Many people live in vulnerable areas because their jobs (fishing, oil and gas refineries, shipping) are there, and they can't afford to live elsewhere (many also live in communities contaminated by toxins, but that's a social injustice rant for another day).
The importance of these people and their jobs to the US economy will become apparent over the next few days, as gas prices rise once again. Some of you might be a little colder than usual this winter, too.
Great article, Greg. I live in Hurricane Land, so I know all about storm surge, winds, torrential rains, and tornadoes. I hate to wish something bad on someone else, but it might help if a major hurricane hit Washington, D.C. Just so they'd understand.
Your mention of the high waves reminded me of a research buoy that, during Hurricane Ivan, measured the tallest wave ever recorded in the Atlantic. 53' high. You can read about it here: Of course, that was open water, but I was in the news control room when Ivan was coming in, and before we lost our BeachCam, the waves were crashing over the Pensacola Beach pier, and if you've ever seen the pier, you know how high it is over a calm sea. Those waves were pretty darn high.
As for the Galveston City Planners -- well, anyone who builds on a barrier island is an idiot. But as long as people are willing to pay big bucks for waterfront property and the privilege of losing everything in a major hurricane, we'll keep seeing development on these islands. They are supposed to protect the coastlines by being able to move and shift. That can't happen with buildings on them. People will never learn.
Aw, snap! 999,986 and I have to leave for work.
Maybe at 2M, Scotty.
What's the latest on you guys getting to vote? I heard katrina refugees had difficulty maintaining their registration.