Hurricane Isaac hits Louisiana, driving dangerous storm surges

By: Dr. Jeff Masters , 2:27 AM GMT on August 29, 2012

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Hurricane Isaac is ashore over Southeast Louisiana, having officially crossed the coast on the Mississippi Delta 90 miles southeast of New Orleans at 7:45 am EDT on August 28. Isaac intensified right up until landfall, striking with 80 mph winds and a central pressure of 970 mb. The storm's large size and large 50 - 60 mile diameter eye kept the intensification rate slow today, but it came quite close to becoming a significantly more dangerous storm. That's because at landfall, Isaac was in the midst of establishing a small inner eyewall within its large 50-mile diameter eye, a very rare feat I've never seen before. Usually, when an eye first forms, it gradually contracts, eventually becoming so small that it becomes unstable. An outer concentric eyewall then forms around the small inner eyewall, eventually becoming the only eyewall when the inner eyewall collapses. But Isaac is a very unusual storm that has continually surprised us, and this inside-out concentric eyewall formation fits the storm's unusual character. The storm isn't in a hurry to move fully inland, and has slowed down to a crawl this evening. This will give the storm the opportunity to keep its center mostly over water a few more hours, and maintain hurricane strength into the early morning on Wednesday.


Figure 1. Radar reflectivity image from New Orleans as Isaac made landfall at 6 pm CDT August 28, 2012.

A dangerous storm surge event underway
Isaac is bringing large and dangerous storm surge to the coast from Central Louisiana to the Panhandle of Florida. At 10 pm EDT, here were some of the storm surge values being recorded at NOAA tide gauges:

6.2' Waveland, MS
9.9' Shell Beach, LA
3.0' Pensacola, FL
4.4' Pascagoula, MS
3.4' Mobile, AL

The 9.9' storm surge at Shell Beach, which is in Lake Borgne 20 miles southeast of New Orleans, exceeds the 9.5' surge recorded there during Category 2 Hurricane Gustav of 2008. Research scientists running a Doppler on Wheels radar located on top of the 16' levees in Plaquemines Parish near Port Sulphur, LA, reported at 8:30 pm EDT that a storm surge of 14' moved up the Mississippi River, and was just 2' below the levees. Waves on top of the surge were cresting over the west side of the levee. Needless to say, they were very nervous. Over the past hour, the surge has retreated some, and waves were no longer lapping over the top of the levee. This is probably due to the fact that we're headed towards low tide. A storm surge of 9.5' has moved up the Mississippi River to the Carrrollton gauge in New Orleans. This is not a concern for the levees in New Orleans, since the storm surge has now brought the river up to 2.5' above its normal water level, which was 7' low due to the 2012 U.S. drought. The highest rise of the water above ground level will occur Wednesday morning over much of Southeast Louisiana, Mississippi, Alabama, and the western Florida Panhandle, when the tide comes back in. It is clear now that this storm surge event will be as dangerous as that of Category 2 Hurricane Gustav of 2008. One piece of good news: NWS New Orleans successfully launched their 00Z balloon. However, their discussion noted the atmosphere is "saturated or nearly saturated" all the way up to 470mb, or 20,000 feet. Precipitable water was 2.76 inches, which will be ripe for extremely heavy rainfall.


Figure 2. Tide gauge data from Shell Beach, located on the south shore of Lake Borgne, just east of New Orleans. The green line shows the storm surge. The red line is the storm tide, the height of the water above Mean Sea Level (MSL.)

Portlight disaster relief charity responds to Issac
The Portlight.org disaster relief charity, founded and staffed by members of the wunderground community, have mobilized resources in advance of the arrival of Hurricane Isaac. Their crew, including 2 EMTs, is at the Biloxi Special Needs Shelter, and will be caring for shelter dwellers and doing rescues of people who call for help. Another team will be surveying all the shelters in the area to ensure that they are accessible to all people. You can donate to Portlight's disaster relief fund here.

I'll have more in the morning. Hunker down, New Orleans. It's going to be a long night.

Jeff Masters

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2069. jpsb
Quoting wunderkidcayman:

oh really Aussie because I'm also part Scottish myself
I am American but 7 of my 8 grand parents are Scots. And I love Scotch Whiskey, must be in the genes.
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2068. 7544
list below
isaac
kirk
98L
possibly 99L off of africa now

what a active augest and the the peak is sept 10 ?
will these other system get close enough to make a run for the us landfalls still? maybe we going to see a couple of home brewed ? and has the mojo arrived yet thanks stay safe
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Quoting Thing342:
Interesting photo of Kirk. He's definitely trying to organize.

Is that a hole, or is Kirk's CoC actually forming an eye?
Member Since: May 17, 2006 Posts: 0 Comments: 635
Quoting DavidHOUTX:


I think the angle Isaac came into NOLA was probably the worst angle possible. What do you think?
For Nola it is

For me it's one of the worst, still gonna get water coming up about 5 feet as it passes to my west
Member Since: June 17, 2011 Posts: 11 Comments: 6461
2065. angiest
Quoting DavidHOUTX:


I think the angle Isaac came into NOLA was probably the worst angle possible. What do you think?


At least very close to being the worst. If I am not mistaken, a track up the MS delta would have been even worse.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
from coming of Africa....In the end....this storm went WELL WEST, look where he is




And this is almost identical of what models were calling for on Isaac when he was out there. Expect this future storm to plow well west in the end too folks, get ready.

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2063. kwgirl
Quoting Patrap:
Nola Roux with first two..
Beautiful Alsatian I believe?
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2062. KEEPEROFTHEGATE (Mod)
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Just getting on this a.m. This thing is just sitting on top of us in Terrebonne Parish. The news is focusing on New Orleans, so can anyone tell me what to expect this storm to do?
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Quoting weatherh98:
Much worse than Gustav


I think the angle Isaac came into NOLA was probably the worst angle possible. What do you think?
Member Since: August 18, 2011 Posts: 0 Comments: 598
Quoting kwgirl:
I will. Are you a Glaswegian or from Edinburgh? They have different accents.

I'm a teddy bear man. if you know what that means you'll know where my family comes from.
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2058. kwgirl
Quoting wunderkidcayman:

oh really Aussie because I'm also part Scottish myself
Ach aye. My wee bairn is Scots by birth. Dunoon, Argyll, Scotland, UK. If you went into a bar and asked about the Scottish people, you would be buying a round, its Scots.
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Interesting photo of Kirk. He's definitely trying to organize.

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Quoting wunderkidcayman:

oh really Aussie because I'm also part Scottish myself

Cool.

I bet I could talk to ya'll and understand every word you say. Maybe you'd ya'll struggle to understand me though.

Anyways. I'm off to bed.

To everyone here that's being effected by Insanity Inducing Isaac. God speed. Stay safe. Stay strong.

Good night Ya'll.

P.S. Isaac, bugger off and find someone else to dump on.
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Much worse than Gustav
Member Since: June 17, 2011 Posts: 11 Comments: 6461
Quoting Asta:


True. The elderly are the hardest to get to leave as they have weathered many storms before.. but it is a different ball game now with the tremendous loss of the wetlands.. there is less of a buffer now. the storms behave differently than what they did when these people were younger.. also they don't want to leave what they know for somethings that they don't know and that won't take their beloved companion pets with them. Someone could make some serious income by creating seasonal storm shelter hotels north of the cane lines.. that take pets..


True, pets are a big part of it. In my experiences, relatives with alzhiemers or maybe mentally challenged in some other way that would not do well anywhere but home. So many reasons besides losing stuff. That was the point I was making. You can replace stuff, if you have the resources.
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2053. angiest
Am I seeing another cyclonic loop? The last couple of radar frames appear to show a little southerly movement.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
That slow crawl and all of the reports coming in are/is painful to watch.........Don't forget to donate some money to Portlight or other relief organizations in the coming days if you can.
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Long Beach is in Mississippi.

Quoting LargoFl:
Longbeach......wish they would put what state.
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2050. ncstorm
Here in NC, if you do not evacuate in a mandatory evacuation, you get fined..personally I think if you live near a levee and a tropical system is approaching, you should go..people only saw Cat 1 and maybe they didnt understand the surge part of it that the NHC/NWS were stressing..everyone is not familiar with the weather as some of us are and only thought a low end Cat 1 and said to themselves "Im not evacuating for that"..for those who are not able to leave due to financial or health reasons and want to but cant, then something needs to be implemented to help them..right now the economy is not the greatest and people are living from paycheck to paycheck...its not as easy as some may think to pack up and pay for a hotel for two days..
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2049. jpsb
Quoting MTWX:


Stuff can be replaced... your lives cannot!!
I was able to save my house and business because I stayed for Ike, I got the water and the mud out of both places the next day. Folks that evacuated had to wait 3 or 4 days before they were allowed back. They all lost their homes. The go, no go call is sometimes difficult. Had I lived on Bolivar I would not have stayed for Ike. I look at the predicted surge and decide if my neighbors home can handle it. My home is only 13 feet above sea level and a one story but his is 16 above and 3 stories. He always gives me the keys before he leaves. I will admit I had my truck packed and was ready to go for Rita, but Rita just kept gaining latitude so I never had to leave. Rita was scary.
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The early runs for the models. I'd imagine though that 98L will end up going more south than that but not as far south as Isaac unless 98L really starts intensifying but who knows at this point. Main focus is Isaac.



Consensus also says hurricane strength is possible.
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Driving today and hearing lots of good Isaac coverage on National Public Radio.
The 42 karat Levees around NOLA worked as intended last I heard. And more heroic community rescues in the bayous.
Meanwhile, there's a nice little anti-cyclone over our new AOI approaching the mid-Atlantic.
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Quoting kwgirl:
Can someone direct me to the post of the pics. I would love to see it and can't bear searching each page. Just a general post number would be good.
Post 233
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2045. snotly
TUNNELS!

Quoting IMA:

hot towers
pin-hole eye
lol It goes on & on
Member Since: Posts: Comments:
Quoting Asta:


wdsu.com
wwltv.com
nola.com
abc26.com

Entergy Outtage map
http://viewoutage.entergy.com/nola.aspx

cleco outtage map for northshore
http://www.cleco.com/site413.php
Link
Member Since: May 17, 2006 Posts: 0 Comments: 635
2043. kwgirl
Quoting AussieStorm:


Nice one... but you read my posts with an accent??? I'm half Scottish though. Will you now read my posts with a Scottish accent.
I will. Are you a Glaswegian or from Edinburgh? They have different accents.
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2042. KEEPEROFTHEGATE (Mod)


moving but ever so slow
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Quoting IMA:

hot towers
pin-hole eye
lol It goes on & on

Night shift.
dry air.
steering maps.
TCHP maps.
Member Since: Posts: Comments:
2040. drs2008
Quoting Badmonkey82009:
After years of lurking, I finally realized how it is you know that you've been lurking on the blog a little too long in one sitting.

1. You wore out your F5 key.
2. You understand Taz on first reading.
3. The Tampa shield doesn't sound like a minor league sports team's name.
4. You read Aussie's posts with an accent.
5. You know (and care) that Pat's dog had puppies.
6. You can define a westcaster, floridacaster, upcaster and downcaster... with examples.
7. You know that, when it comes to hurricanes, sometimes science is an art.
8. You randomly crave Fresca.
9. Jim Cantore causes you physical pain when he is on TV.
10. You root for a thunderstorm of the CV islands to become a hurricane then you try to steer into open ocean it by sheer force of will.
11. You.stop.noticing.dots.between.words.
12. You find yourself genuinely hoping that people you've never met get through the storm safely.

Thanks to everyone who posts the "good stuff". To everyone affected.. be safe, you are in my thoughts and prayers. Returning to lurking.
Best blog of the day !!
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Shingles are being peeled off our roof now. Scattering across the yard....
Member Since: June 17, 2011 Posts: 11 Comments: 6461
Just got off the phone with my dad, and he's around the 1800 block of S. Carrolton. They had power up until 6am. Lots of rain & wind, with roof shingles and debris all over the street. There are power lines down, in the streets. But no flooding...

Quoting Giga2001:
Can anyone give me a general idea of the status in NOLA? Specifically the areas of Algiers Point, the area near the Maple Leaf Bar (Uptown/Carrolton) and St Charles Ave around the 1700 block?

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Quoting AussieStorm:


Nice one... but you read my posts with an accent??? I'm half Scottish though. Will you now read my posts with a Scottish accent.


It's one in the same

I read it with an accent to:)
Member Since: June 17, 2011 Posts: 11 Comments: 6461
Quoting AussieStorm:


Nice one... but you read my posts with an accent??? I'm half Scottish though. Will you now read my posts with a Scottish accent.

oh really Aussie because I'm also part Scottish myself
Member Since: Posts: Comments:
2035. Relix
any takes on 98L? Have an event here in PR on Sunday and want to see if that recurve seems more likely than not.
Member Since: Posts: Comments:
2034. kwgirl
Quoting Asta:


True. The elderly are the hardest to get to leave as they have weathered many storms before.. but it is a different ball game now with the tremendous loss of the wetlands.. there is less of a buffer now. the storms behave differently than what they did when these people were younger.. also they don't want to leave what they know for somethings that they don't know and that won't take their beloved companion pets with them. Someone could make some serious income by creating seasonal storm shelter hotels north of the cane lines.. that take pets..
Here in the Keys the shelters have started taking pets. No one will leave their pet (child) in a storm, so to encourage people to leave they allow the pets. This should be standard. Of course, the shelters were searching people and would not allow tobacco, so a lot of people turned themselves away when that happened. It's a balancing act. Most people I know won't go to shelter because they don't allow beer!
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2033. new2you
I have a sister who lives Lakeview, LA and one of her neighbors sent her a pic of roof tiles blowing off her roof. Glad they got out of there.
Member Since: Posts: Comments:
Quoting Asta:


wdsu.com
wwltv.com
nola.com
abc26.com

Entergy Outtage map
http://viewoutage.entergy.com/nola.aspx

cleco outtage map for northshore
http://www.cleco.com/site413.php


Of course - i should have thought of most of that. Sheesh, i'm just not thinking quite straight this morning.

Thank you so much.
Member Since: Posts: Comments:
Quoting Badmonkey82009:
After years of lurking, I finally realized how it is you know that you've been lurking on the blog a little too long in one sitting.

1. You wore out your F5 key.
2. You understand Taz on first reading.
3. The Tampa shield doesn't sound like a minor league sports team's name.
4. You read Aussie's posts with an accent.
5. You know (and care) that Pat's dog had puppies.
6. You can define a westcaster, floridacaster, upcaster and downcaster... with examples.
7. You know that, when it comes to hurricanes, sometimes science is an art.
8. You randomly crave Fresca.
9. Jim Cantore causes you physical pain when he is on TV.
10. You root for a thunderstorm of the CV islands to become a hurricane then you try to steer into open ocean it by sheer force of will.
11. You.stop.noticing.dots.between.words.
12. You find yourself genuinely hoping that people you've never met get through the storm safely.

Thanks to everyone who posts the "good stuff". To everyone affected.. be safe, you are in my thoughts and prayers. Returning to lurking.


LOl....and I find myself shaking my head in agreement to all 12 as I read it.
Member Since: Posts: Comments:
Coming in from mandeville, 3.20 inches of rain.

Gusts around hurricane force.

Only getting worse folks

No power till at least sept 2nd.
Member Since: June 17, 2011 Posts: 11 Comments: 6461
Quoting JasonRE:


Yeah, just wondering. Thanks for the info. Even though we'll be on the West side, it still seems like we would get quite a bit of rain. I see someone posted this could possibly run the coast to SE TX and then North? That would dump on us big time....

yep, lots of rain. The groud and trees are saturated already. Big concern is branches or trees falling causing power outages.
Member Since: September 5, 2007 Posts: 0 Comments: 3481
Quoting Badmonkey82009:
After years of lurking, I finally realized how it is you know that you've been lurking on the blog a little too long in one sitting.

1. You wore out your F5 key.
2. You understand Taz on first reading.
3. The Tampa shield doesn't sound like a minor league sports team's name.
4. You read Aussie's posts with an accent.
5. You know (and care) that Pat's dog had puppies.
6. You can define a westcaster, floridacaster, upcaster and downcaster... with examples.
7. You know that, when it comes to hurricanes, sometimes science is an art.
8. You randomly crave Fresca.
9. Jim Cantore causes you physical pain when he is on TV.
10. You root for a thunderstorm of the CV islands to become a hurricane then you try to steer into open ocean it by sheer force of will.
11. You.stop.noticing.dots.between.words.
12. You find yourself genuinely hoping that people you've never met get through the storm safely.

Thanks to everyone who posts the "good stuff". To everyone affected.. be safe, you are in my thoughts and prayers. Returning to lurking.


Nice one... but you read my posts with an accent??? I'm half Scottish though. Will you now read my posts with a Scottish accent.
Member Since: Posts: Comments:
Link
Member Since: Posts: Comments:
2024. Asta
Quoting Giga2001:
Can anyone give me a general idea of the status in NOLA? Specifically the areas of Algiers Point, the area near the Maple Leaf Bar (Uptown/Carrolton) and St Charles Ave around the 1700 block?



wdsu.com
wwltv.com
nola.com
abc26.com

Entergy Outtage map
http://viewoutage.entergy.com/nola.aspx

cleco outtage map for northshore
http://www.cleco.com/site413.php
Member Since: Posts: Comments:
since Isaac is moving so slowly, will that tropical wave between Cuba and the Yucatan interact with Isaac?
Member Since: Posts: Comments:
Quoting FrancesJeanne:
lol! I so relate...my poor coworkers must think of WU like a soap opera. I've actually been waiting for one of my friends to get to work so I can show her the pic of Nola Roux & her puppies lol
There's a picture of puppies?!
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2021. drs2008
Quoting MTWX:


Stuff can be replaced... your lives cannot!!
This is one of the reasons we have a curfew in Biloxi.
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2020. kwgirl
Quoting FrancesJeanne:
lol! I so relate...my poor coworkers must think of WU like a soap opera. I've actually been waiting for one of my friends to get to work so I can show her the pic of Nola Roux & her puppies lol
Can someone direct me to the post of the pics. I would love to see it and can't bear searching each page. Just a general post number would be good.
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Quoting IMA:

hot towers
pin-hole eye
lol It goes on & on


and lets not forget the ants!
Member Since: September 5, 2007 Posts: 0 Comments: 3481

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