Levees 'cannot save New Orleans'; BBC

[Derek Ortt]

Agree....i can only hope that one positive consequence of the last few years is that so many people have become more storm savy than ever. People need to listen to the evacuation orders and forecast surge heights...and act accordingly. Every storm is different and if officials say go....go!

Don't want to totally discount the effect of wind....although i do agree it is surge that generally kills and destroys the most. There are noteable and graphic exceptions to that....just think the photos out of Homestead of block after block of destroyed homes from Andrew. A quarter million people....comprising 100,000+ homes....were made homeless from wind damage. Not blue roof cases or lost tiles...we're talking homeless.

I usually dont become too concerned with wind until the upper cat 3 range. That is when the gusts become the equivalent of EF4 tornadoes. Of course, in a cat 5 hurricane... you may not have that much protection from wind in any shelter if you are within one of the miniswirls (and I suspect that the 212 mph gust in Cuba from Gustav was a miniswirl... that should tell you just how violent those can be... and that was in a cat 4 hurricane... so Andrew's may have been closer to 235 mph or even higher). That is even more violent than nearly ALL TORNADOES

[jinftl]

Makes me wonder if there aren't some storm events....say a potential landfalling Cat 4 or 5...where the 'unless you are in a surge evacuation zone, stay home/stay local' mantra in south florida might be a bad move. Not sure an Andrew-type eyewall travelling down I-595 in Broward or 826 or 836 in Miami-Dade would have a good outcome with so many folks in such a force's way.

Agree....i can only hope that one positive consequence of the last few years is that so many people have become more storm savy than ever. People need to listen to the evacuation orders and forecast surge heights...and act accordingly. Every storm is different and if officials say go....go!

Don't want to totally discount the effect of wind....although i do agree it is surge that generally kills and destroys the most. There are noteable and graphic exceptions to that....just think the photos out of Homestead of block after block of destroyed homes from Andrew. A quarter million people....comprising 100,000+ homes....were made homeless from wind damage. Not blue roof cases or lost tiles...we're talking homeless.

I usually dont become too concerned with wind until the upper cat 3 range. That is when the gusts become the equivalent of EF4 tornadoes. Of course, in a cat 5 hurricane... you may not have that much protection from wind in any shelter if you are within one of the miniswirls (and I suspect that the 212 mph gust in Cuba from Gustav was a miniswirl... that should tell you just how violent those can be... and that was in a cat 4 hurricane... so Andrew's may have been closer to 235 mph or even higher). That is even more violent than nearly ALL TORNADOES

[Derek Ortt]

I wonder about that myself... if someone asked me if they should stay or leave, I'd have to think very long and hard about telling someone it is OK to stay where there is a chance of equivalent EF5 tornadoes

[vbhoutex]

I wonder about that myself... if someone asked me if they should stay or leave, I'd have to think very long and hard about telling someone it is OK to stay where there is a chance of equivalent EF5 tornadoes

That is pretty much my thinking. I don't have to worry about surge where I am, just localized flooding from overflowing bayous and street flooding. Wind is the major factor in my decision to stay or leave along with the fact I have huge trees in my yard, some which were pretty messed up by Ike. Makes me think long and hard about staying for anything more than expecting CAT2 winds where I live in Houston.

[MGC]

I have to worry about both wind and water as I live 2 blocks from the GOM. We are on the highest land in Pass Christian, about 30 feet above sea level. The water approached within 100 feet of our home, from a bayou behind the house, not the gulf. Katrina was the only hurricane I have ever evacuated for. We made the call to leave Sunday morning shortly after the upgrade to Cat-5. I feel we did the right thing in leaving, I wish some of my neighbors did the same. The stench of death was in the air for days after the hurricane. Even though Katrina was no longer a Cat-5, thanks to a well timed eyewall replacement cycle, some dry air and some shear, the hurricane did produce considerable wind damage. There are many places where wind streaks from collasping convective cells produced total destruction. Entire swaths of trees were snapped off mid trunk. Clearly wind gusts in these areas well exceeded the sustained winds. Luck for us the neighbors home, a two story, blocked the wind a bit. His roof did end up in our back yard though. I guess if I lived inland in Miami area and another Andrew was approaching I'd leave. Even if your house is well build, few can survive wind gusts approaching 200mph. Plus, the aftermath of the hurricane totally sucks. I'd rather be in Disney World.......MGC

[Dionne]

I know that nobody really knows the actual number of persons that evacuated NOLA for Katrina. If you run a Google search there are lots of opinions. Basically there were around 1.3 million folks in the greater NOLA area. It is estimated that upwards of 1 million evacuated. 20-25 thousand remained in the city. That's a pretty good evac considering the city only rates a 67.3% evacuation potential, while 70% of the city is below sea level.

I did read something interesting about the difference between the Cat 3 and the Cat 5. It's the difference between getting hit by an 18 wheeler versus a freight train.

[wxman57]

That is pretty much my thinking. I don't have to worry about surge where I am, just localized flooding from overflowing bayous and street flooding. Wind is the major factor in my decision to stay or leave along with the fact I have huge trees in my yard, some which were pretty messed up by Ike. Makes me think long and hard about staying for anything more than expecting CAT2 winds where I live in Houston.

Problem is, you will have to make your decision to evacuate or not long before you know what you'll be facing in terms of wind at your home. A Cat 2 can strengthen to a Cat 4 in 6 hours just prior to landfall (Charley), and that strengthening may not be forecast. You'll have to decide to evacuate or not 2 days before impact. Plenty of time for strengthening, despite what the forecast may say. Remember, we've made almost no improvement in intensity forecasting in the last 20 years.

For most in Houston (outside a surge zone), it may be best to ride out the storm at home then make nay needed repairs to your home to prevent additional damage once the storm passes. If it looks like power may be out for a while, then leave to stay with friends/relatives for a week or two. That'll let those who need to get out of surge zones evacuate safely.

Up in Spring Branch, it would take quite a hurricane to bring sustained Cat 2 winds with gusts in the 120-130 mph range. That kind of wind can peel roofs off houses and cause roof failure/home destruction. Probably a good solid Cat 4 with Cat 4 winds covering a significant area and a hit that would being those strongest winds right over you. It would also have to be strengthening at landfall, or at least not experiencing weakening due to shear or dry air intrusion at landfall.

[vbhoutex]

That is pretty much my thinking. I don't have to worry about surge where I am, just localized flooding from overflowing bayous and street flooding. Wind is the major factor in my decision to stay or leave along with the fact I have huge trees in my yard, some which were pretty messed up by Ike. Makes me think long and hard about staying for anything more than expecting CAT2 winds where I live in Houston.

Problem is, you will have to make your decision to evacuate or not long before you know what you'll be facing in terms of wind at your home. A Cat 2 can strengthen to a Cat 4 in 6 hours just prior to landfall (Charley), and that strengthening may not be forecast. You'll have to decide to evacuate or not 2 days before impact. Plenty of time for strengthening, despite what the forecast may say. Remember, we've made almost no improvement in intensity forecasting in the last 20 years.

For most in Houston (outside a surge zone), it may be best to ride out the storm at home then make nay needed repairs to your home to prevent additional damage once the storm passes. If it looks like power may be out for a while, then leave to stay with friends/relatives for a week or two. That'll let those who need to get out of surge zones evacuate safely.

Up in Spring Branch, it would take quite a hurricane to bring sustained Cat 2 winds with gusts in the 120-130 mph range. That kind of wind can peel roofs off houses and cause roof failure/home destruction. Probably a good solid Cat 4 with Cat 4 winds covering a significant area and a hit that would being those strongest winds right over you. It would also have to be strengthening at landfall, or at least not experiencing weakening due to shear or dry air intrusion at landfall.

I understand exactly what you are saying. When Rita was coming in I waited till Friday at 1 am to decide to stay, which may have been too late if she had hit as originally expected and at the strength expected. With Ike it was a no brainer to stay with the house even though I was shocked by the damage in our area. That is what will make me take off for my son's house in Cypress(no big trees) if we are facing something like you or I have described strength wise.

[mitchell]

Problem is, you will have to make your decision to evacuate or not long before you know what you'll be facing in terms of wind at your home.

yeah i hear you on that. I was looking at the US Army Corp Evacuation study for the Delmarva peninsula. Evacuation times about 30 hours, and getting people out before TS force winds, the evacuation decision point is about 40 hours ahead of closest approach. Has anyone seen the forecast cone for a storm moving at 20-25 mph forward speed 40 hours before a mid atlantic strike. The storm is off Florida and the cone from Norfolk to New York. Good luck!