Surge/wind questions - evacuation decisions

[cat]

Greetings.

I've got a few questions about storm surge and wind damage:

1. In let's say a cat 4 or 5 storm, I understand the storm surge levels can be expected to be anywhere from 13 to 22 feet, give or take. Taking this into account, what would be the possibilities of a modern condo being removed off it's foundation as the surge moves in either in or out. Specifically, I'm talking about buildings that have been built on a coral bed and not on the sand - ie - buildings west of the intracoastal in fla vs those built on the sand in miami beach, ft lauderdale. I've seen some of what Camille did to buildings on the beach (the well known case of the Richelieu Apartments), and I'm curious if the same type of damage occurs to buildings which have foundations built on coral bedrock.

2. In recent newscasts, I've heard it said that the reason evacuations are ordered for beachfront condos, etc isn't so much that authorities fear a collapse of the buildings, but are more concerned about people who live on such barrier land masses being cut off from help after the storm. What are your comments on this. Additionally, does anyone have any URL's to studies done on the effects of storm surge on building foundations?

3. I understand that wind damage from a storm increases exponentially. The numbers I've heard, for instance, that the level of damage from let's say a cat 1 storm with winds of 75 mph vs. that of a cat 4 storm with winds of 150 is estimated to be 250 times greater. Does anyone have a URL for either the mathematical formulas used to determine or calculate these figures or one that might detail the actual increase in damage for different wind speeds?

Basically, the reason why I'm posing these questions is this: My fiance and I live on a 5th floor condo located exactly .706 miles from the ocean in ft. lauderdale. I'm looking at the different options we have in case Ivan comes in as a 4 or 5. It breaks down like this:

- either stay knowing that we are certainly out of flood range (providing the building doesn't literally fall in the drink or

- "evacuate" to areas west which very well might wind up in a flood zone considering this surge may extend inland 6 to 10 miles (in a cat 5 storm)

Things begin to look like a jump from the frying pan into the fire

Any comments appreciated and welcome. TIA.

[hibiscushouse]

but are more concerned about people who live on such barrier land masses being cut off from help after the storm

Anyone remember Elena in Pinellas County (Clearwater and Gulf Beaches)? The main causeways to Tampa were underwater. The entire county was a barrier island at that point, not just the gulf beaches.

[Guest]

1. Don't know.
2. Actually, it has to do with coastal flooding. Most hurricane deaths are caused by drowning.
3. http://www.nhc.noaa.gov/aboutsshs.shtml
...Jennifer...

[chadtm80]

1. Don't know.
2. Actually, it has to do with coastal flooding. Most hurricane deaths are caused by drowning.
3. http://www.nhc.noaa.gov/aboutsshs.shtml
...Jennifer...

You make me so proud.. I want to cry lol

[AlexiBlue]

My two story condo apartment is 15 MILES from the ocean and built on one of the few actual rock areas in Charleston. The closest waterway is a tidal inlet that is about 7 miles away.

When Hugo hit here, not only was the first floor of this building entirely flooded, but the storm ripped off the roof of the building - all of it. Sure, the frame survived and they rebuilt the building - but you can bet I'm not staying here in a hurricane!

You are .706 miles from the ocean. You have storm surge AND rain flooding AND wind. The hurricane is not attacking the coral your condo is sitting on. It is attacking your CONDO.

You don't need mathmatical charts to figure out that even a tropical storm could cause you damage - and a hurricane could wipe you off the map.

Listen to your authorities. If you are ordered to evacuate - do it. Period, end of story, no questions, no arguements. Your life and the life of your fiance aren't worth playing russian roulette with a hurricane.

[FritzPaul]

During Camille there was suppose to be a hotel/condo (Don't remember which) that was suppose to be hurricane proof along the gulf coast because of its concrete foundation. After the storm, all that was left was the concrete foundation. Everything else was gone!

[betsy65freddy79]

I agree with listening to authorities. By the same token - where will anyone in South Florida go to evacuate? The shelters are full, there are few supplies, we can't go west, there is no place to stay north, and the Keys may get hit by Ivan. Gasoline is still difficult to obtain in some areas and one would not want to run out when evacuating. If Ivan takes the track that may be most likely now, going north could be the worst thing for someone in FT. Lauderdale to do. If you can get out of the state, that would be the best thing to do now. In my humble opinion.

[cat]

You are .706 miles from the ocean. You have storm surge AND rain flooding AND wind. The hurricane is not attacking the coral your condo is sitting on. It is attacking your CONDO.

You don't need mathmatical charts to figure out that even a tropical storm could cause you damage - and a hurricane could wipe you off the map.

Listen to your authorities. If you are ordered to evacuate - do it. Period, end of story, no questions, no arguements. Your life and the life of your fiance aren't worth playing russian roulette with a hurricane.

The points you make are good ones. However, the dilemma with simply "evacuating" is this:

The furthest point west most of us here in Ft. Lauderdale could evacuate west would be about 6 miles - give or take. That would put me (us) on the fringes of the everglades and at about 1 foot above sea level. Now apply your experience and numbers of being 15 miles from the coast and your first floor being totally flooded.

"Evacuating" doesn't look or sound so good now, does it.

[cat]

I agree with listening to authorities. By the same token - where will anyone in South Florida go to evacuate? The shelters are full, there are few supplies, we can't go west, there is no place to stay north, and the Keys may get hit by Ivan. Gasoline is still difficult to obtain in some areas and one would not want to run out when evacuating. If Ivan takes the track that may be most likely now, going north could be the worst thing for someone in FT. Lauderdale to do. If you can get out of the state, that would be the best thing to do now. In my humble opinion.

This is actually a great idea and one we are entertaining. I'm trying to convince my fiance to get on a jet and head out of town and join her family in Boston. Her brother is flying his entire family out of town. Others I know who can are doing the same. We tried to find her a flight last night, but most are sold out now. We are still looking.

[cat]

During Camille there was suppose to be a hotel/condo (Don't remember which) that was suppose to be hurricane proof along the gulf coast because of its concrete foundation. After the storm, all that was left was the concrete foundation. Everything else was gone!

That was the Richelieu Apartments I mentioned earlier:

http://www.disasterrelief.org/Disasters/990816Camille/

[ricreig]

You are .706 miles from the ocean. You have storm surge AND rain flooding AND wind. The hurricane is not attacking the coral your condo is sitting on. It is attacking your CONDO.

You don't need mathmatical charts to figure out that even a tropical storm could cause you damage - and a hurricane could wipe you off the map.

Listen to your authorities. If you are ordered to evacuate - do it. Period, end of story, no questions, no arguements. Your life and the life of your fiance aren't worth playing russian roulette with a hurricane.

The points you make are good ones. However, the dilemma with simply "evacuating" is this:

The furthest point west most of us here in Ft. Lauderdale could evacuate west would be about 6 miles - give or take. That would put me (us) on the fringes of the everglades and at about 1 foot above sea level. Now apply your experience and numbers of being 15 miles from the coast and your first floor being totally flooded.

"Evacuating" doesn't look or sound so good now, does it.

No offense intended, but, It really seems you've made your decision already...to stay. If that is the case and given that the opinions expressed by those replying seem universal: Leave if threatened, why did you post the question in the first place? Those were excellent questions, IF, you didn't already 'know' the answers or were going to ignore good advice. No one suggested evacuating to the everglades. Yes, gas is scarce, but you *can* get it on your way to safer ground.

You and the EC Florida are NOT out of the woods, but more and more it is starting to look like the questions would be better asked with the NEXT storm that comes to SE coastal Florida. Makes the questions, sort of moot.

Richard

[SeaBrz_FL]

Here's a link to a photo I took in Cocoa Beach on Tuesday. My back is to the ocean. The storm surge went over the roof of this beachfront motel and, after the surge receded, this is what was left behind.

Cocoa Beach was 100 miles north of Frances' landfall.

http://img.photobucket.com/albums/v443/ ... 070020.jpg

[inotherwords]

The furthest point west most of us here in Ft. Lauderdale could evacuate west would be about 6 miles - give or take.

Not true. If you knew a couple days in advance it was coming directly into your area, meaning from S. Miami up to say, West Palm, and that it wasn't forecast to bisect the state like Frances, you could go west across alligator alley and up 75 until you're out of the projected hurricane force wind area. I had refugees from Floyd staying here in 99.

Of course we on the west coast are in the sights right now, so I'm thinking about coming your way via the reverse route if the track stays the way it is. I did that with Charley and it worked out fine. I left late, though, after the first feeder band went through, and traveled in the middle of the night across 70/72 to 95 and then south just because I was concerned about getting stuck if I went toward the storm. But as I said, I left late, and am prepared to leave a lot earlier this time.

I was all set yesterday to evacuate out of the state, but with animals, I'd have to drive, and we'd just end up in Georgia somewhere and then would have to deal with where Ivan was going after it left FL. And then there's the whole issue of being able to get back. I'd think it would be easier to get back from one coast to the other because that's one tank of gas.

Don't forget for you, there are also shelters inland. Most of those buildings are selected because they are supposedly built to withstand higher force winds. Of course there are no guarantees (see Arcadia) but I'd think this would be the best bet if you get "stuck."

[tronbunny]

Good morning folks.
Yesterday, Gov. Jeb said that it is "unrealistic" for most folks to evac. Only those, on the mainland, that are in damaged, unprotected, modular homes or low lying areas should evac.
Most can go to local shelters if they feel their homes are not fairly sturdy. If you're boarded up, and live in a sturdy (yes even wood frame - inland) find a safe room and hunker down there.
If you don't want the hassle, got to a local shelter. Your house can wait for you and the storm, while you have the resources of food and hopefully good company.

[Mello1]

Greetings.

I've got a few questions about storm surge and wind damage:

1. In let's say a cat 4 or 5 storm, I understand the storm surge levels can be expected to be anywhere from 13 to 22 feet, give or take. Taking this into account, what would be the possibilities of a modern condo being removed off it's foundation as the surge moves in either in or out. Specifically, I'm talking about buildings that have been built on a coral bed and not on the sand - ie - buildings west of the intracoastal in fla vs those built on the sand in miami beach, ft lauderdale. I've seen some of what Camille did to buildings on the beach (the well known case of the Richelieu Apartments), and I'm curious if the same type of damage occurs to buildings which have foundations built on coral bedrock.

As I'm sure you know now, judging from some of the posts, Cat 4 or 5 range is in the extreme to catastrophic levels of structural damage. A direct eyewall hit at Cat 4 or 5 will cause severe structural damage no matter what kind of foundation a building has. Another site you can visit that will give you a graphic on storm surges based on Cat level is here:
http://www.srcc.lsu.edu/OEP/hurr_scale.html

2. In recent newscasts, I've heard it said that the reason evacuations are ordered for beachfront condos, etc isn't so much that authorities fear a collapse of the buildings, but are more concerned about people who live on such barrier land masses being cut off from help after the storm. What are your comments on this. Additionally, does anyone have any URL's to studies done on the effects of storm surge on building foundations?

Check out the url stated above. Also, for future reference, you can always do a Google search on this and it will bring up more sites that you may not have the time to read. If I find something better, I will post it.

3. I understand that wind damage from a storm increases exponentially. The numbers I've heard, for instance, that the level of damage from let's say a cat 1 storm with winds of 75 mph vs. that of a cat 4 storm with winds of 150 is estimated to be 250 times greater. Does anyone have a URL for either the mathematical formulas used to determine or calculate these figures or one that might detail the actual increase in damage for different wind speeds?

Basically, the hurricane cat scale was developed by Saffir-Simpson. Herbert Saffir is a structural engineer who is credited with helping to re-write Florida's structural building codes. While I couldn't find specific information on the formulas used to calcuate the point of structural failure based on wind speed, pressure, surge, etc., this url has a little more of a technical description of the process behind the the SS Cat scale:
http://www.es.mq.edu.au/nhrc/web/scales/scalespage7.htm

Basically, the reason why I'm posing these questions is this: My fiance and I live on a 5th floor condo located exactly .706 miles from the ocean in ft. lauderdale. I'm looking at the different options we have in case Ivan comes in as a 4 or 5. It breaks down like this:

- either stay knowing that we are certainly out of flood range (providing the building doesn't literally fall in the drink or

- "evacuate" to areas west which very well might wind up in a flood zone considering this surge may extend inland 6 to 10 miles (in a cat 5 storm)

Things begin to look like a jump from the frying pan into the fire

Any comments appreciated and welcome. TIA.

I think the main point here is to watch and wait. The kind of damage that was caused in Pass Christian, MS during Hurricane Camille was the result of a direct Cat 5 hit and if memory serves me correctly, there hasn't been anything like that until Hurricane Andrew, but even with that, the position of Camille and how it hit caused the rare worst possible scenaro. If it is a matter of COMFORT and PEACE OF MIND of not having to worry about where and when and how Ivan is going to hit, you may want to consider leaving right now. Given the current state of affairs in Florida after having under gone two cane hits in a month, decisions to go or stay has to be made early to avoid the crunch. It's hard to say what one would actually do in this situation because it depends on ones nerve tolerance level at this point; I know you guys are understandably on edge right now. The most practical advice is to wait to see what this storm will do, then follow the directives of your local officials. If mandatory evacs are called for, you should heed the advice. You should now know your ground evac routes and location of shelters if you cannot or are not able to get very far. In any case, make your plan now and stick to it. Good luck.

[karenfromheaven]

I'm not a professional structural engineer, but I have Masters degrees in Electrical Engineering, so I know my way around a formula or two.

1. Foundations can be successfully built in underwater sand. Just look at the nearest bridge piling. These reinforced concrete pilings are pounded deep into the sand, and they are designed to be pounded in until the force exerted upon the piling by the sand reaches a high level specified by the design engineer. Typically, this force is expressed as a function of the cross-sectional area of the piling, so it is a pressure measurement in psi. It's typically a huge number, in the thousands of pounds-per-square-inch. The pilings take the weight of the entire structure, tons and tons of it, and transmit it into the sand. The forces from waves are only a fraction of the total force. A modern condo is not likely to be swept away.

2. I'm not sure if you are "certainly out of flood range" being only .706 mi from the ocean. Your building may have no trouble remaining upright in the wind and rain, but my question for you is, are you prepared to ride out the storm surrounded by churning, foaming water, with pounding surf carrying your car away as you watch from above through your blown out windows and doors? Do you have an interior room to retreat to without windows to the outside? You will not be able to keep your eyes open in wind-driven rain at 120+ mph. This could be a problem if it's in your living space.

3. There was a link here yesterday to a study of buildings and houses that survived Hurricane Andrew. Sorry I can't remember it at the moment, but it was quite informative about failure modes in high wind. However, I can give you an illustration of the wind's power.

I'm a sailor, and here is a formula used to predict the amount of force a sail will experience in a wind: F = 0.004*V^2*A where F is the wind force in pounds, V is the wind velocity in mph, and A is the area in sq feet. Notice that the force from the wind is indeed exponential; it increases as the square of the velocity. For example, let's calculate the force a sliding glass door would have to resist in a 100 mph wind:

Assume a glass door size of 7' by 3' -- the area is 21 sq feet. Therefore we have

F = 0.004 * (100*100) * 21
F = 840 lbs!

Picture the door propped up horizontally with sawhorses on end and 5 adults standing on the door. Would yours hold or cave in? Now let's increase the wind speed to 140 mph:

F = 0.004 * (140*140) * 21
F = 1646 lbs!!!

Just about double! 10 adults? I don't think so. I'm not sure, but I think the current building code requires windows in FL to be able to withstand 120 mph winds. Windows, doors, and walls must all sucessfully resist these forces, and do so in the face of impacts from flying debris. To make matters worse, windspeed increases as your height above the ground increases. I don't remember the formula to estimate this increase, but it can be significant in high-rise structures.

You're facing a difficult decision and the choice doesn't seem clear-cut to me either. Being caught in storm surge at the height of the storm would be horrible. Even if you could keep your head above water, the waves will have tons of debris floating in them, and it would be nearly impossible to keep from being seriously injured while in the water. Make a choice that keeps you protected and out of the water. Keep asking questions and searching out the best information. All the best, Karen

[nccoastalgirl]

I live on the coast in NC, and I can only tell you that based on my experience, if you have a an evacuation order, obey it. If you have any doubts as to the destruction that a direct hit by a Cat. 4 or 5 hurricane can cause, then you only have to look at pictures from past hurricanes on the internet. No building code, none, can guarantee any structure to withstand sustained winds like those in a Cat. 4 or 5 hurricane. Most deaths are in fact caused by the absolutely amazing power of the storm surge, though. It's much worse than the wind. You are too close to the water to ignore that fact. Storm surges and floods are what kill most people in hurricanes. If Ivan comes your way, leave your condo. That's my "old salty," unscientific advice for the day. Always err on the side of safety. A storm shelter is probably your best bet in this situation. Best wishes.

[cat]

You are .706 miles from the ocean. You have storm surge AND rain flooding AND wind. The hurricane is not attacking the coral your condo is sitting on. It is attacking your CONDO.

You don't need mathmatical charts to figure out that even a tropical storm could cause you damage - and a hurricane could wipe you off the map.

Listen to your authorities. If you are ordered to evacuate - do it. Period, end of story, no questions, no arguements. Your life and the life of your fiance aren't worth playing russian roulette with a hurricane.

The points you make are good ones. However, the dilemma with simply "evacuating" is this:

The furthest point west most of us here in Ft. Lauderdale could evacuate west would be about 6 miles - give or take. That would put me (us) on the fringes of the everglades and at about 1 foot above sea level. Now apply your experience and numbers of being 15 miles from the coast and your first floor being totally flooded.

"Evacuating" doesn't look or sound so good now, does it.

No offense intended, but, It really seems you've made your decision already...to stay. If that is the case and given that the opinions expressed by those replying seem universal: Leave if threatened, why did you post the question in the first place? Those were excellent questions, IF, you didn't already 'know' the answers or were going to ignore good advice. No one suggested evacuating to the everglades. Yes, gas is scarce, but you *can* get it on your way to safer ground.

You and the EC Florida are NOT out of the woods, but more and more it is starting to look like the questions would be better asked with the NEXT storm that comes to SE coastal Florida. Makes the questions, sort of moot.

Richard

I asked the questions for one reason only: To gather more information - information I may not have - to make the best decision I possibly can about what to do.

I don't agree with your assessment of my questions being excellent or not based on what I do with the information gleaned from them.

That's just plain silly.

What you really mean to say is that you aren't liking what you percieve to be my conclusions and my decisions, so why not just put it on the table and say that

And no, I wouldn't simply evacuate unless the reasons to evacuate make sense to me and a viable location to evacuate *to* exists.

Insofar as the Everglades go, I think you missed my point - which is this: For a cat 5 storm, storm surge is estimated to travel inland 6 to 10 miles based on what I've read. That puts an awful lot of people in South Florida in a very precarious situation. If you can't go west, then that means you have to go north. A million or more people trying to go north in more or less the same time frame and on two major arteries out of town is not a situation that sounds appealing to me at all.

And how sure are you that I *can* get gas further north of here since the reports I'm hearing from family in Palm Beach and Port St. Lucie seem to conflict with your information? Incidently, Jeb Bush signed a law on Sunday giving him the power to allocate gas to repair and service crews before the civilian population if it comes down to that. To me, that takes points away from the car evac option.

Considering that it's going to be a couple of days or more before Ivan arrives, it hardly makes the questions moot, either, by the way.

That still gives me and mine a good day or more yet to make our decisions.

[Guest]

"A million or more people trying to go north in more or less the same time frame and on two major arteries out of town is not a situation that sounds appealing to me at all."

Sounds more appealing to me than the possibility of death, but hey, to each his own.

"And how sure are you that I *can* get gas further north of here since the reports I'm hearing from family in Palm Beach and Port St. Lucie seem to conflict with your information? Incidently, Jeb Bush signed a law on Sunday giving him the power to allocate gas to repair and service crews before the civilian population if it comes down to that. To me, that takes points away from the car evac option."

IF IT COMES DOWN TO IT. As of right now, that has not happened. The gas situation is getting better by the day in Central FL. I got gas three days or so and it took 45 mins. I got gas today and it took 2 mins. If you can make it to the central part of the state, you'll be okay as far as getting gas. But you should leave soon.

"That still gives me and mine a good day or more yet to make our decisions."

Every day, the traffic and gas situation is going to get worse and worse. If you are going to evacuate north, now is the time to go. If you're just considering going inland more, you do have another day or so to decide. Like I said before, good luck in whatever you decide to do.

[cat]

The furthest point west most of us here in Ft. Lauderdale could evacuate west would be about 6 miles - give or take.

Not true. If you knew a couple days in advance it was coming directly into your area, meaning from S. Miami up to say, West Palm, and that it wasn't forecast to bisect the state like Frances, you could go west across alligator alley and up 75 until you're out of the projected hurricane force wind area. I had refugees from Floyd staying here in 99.

Of course we on the west coast are in the sights right now, so I'm thinking about coming your way via the reverse route if the track stays the way it is. I did that with Charley and it worked out fine. I left late, though, after the first feeder band went through, and traveled in the middle of the night across 70/72 to 95 and then south just because I was concerned about getting stuck if I went toward the storm. But as I said, I left late, and am prepared to leave a lot earlier this time.

I was all set yesterday to evacuate out of the state, but with animals, I'd have to drive, and we'd just end up in Georgia somewhere and then would have to deal with where Ivan was going after it left FL. And then there's the whole issue of being able to get back. I'd think it would be easier to get back from one coast to the other because that's one tank of gas.

Don't forget for you, there are also shelters inland. Most of those buildings are selected because they are supposedly built to withstand higher force winds. Of course there are no guarantees (see Arcadia) but I'd think this would be the best bet if you get "stuck."

How was the situation out on 75 north? I heard it was a mess if you trying to go in that direction.

I like your idea and we have some friends over in Sarasota, so this might actually be the best option. I just called my niece over in Ft. Meyers and offered to her to do the same if thing if things get dicey on her side of the state.

My concerns are also yours, too - the critters (we have 3 cats) and getting back in after it's all over. But I think if push comes to shove this might be the best idea yet.