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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My son pasted this on his facebook page with a map of his track.


Sounds like I have alot of son's, but only three. This is the youngest one.
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1768. Asrock
Quoting angiest:


It doesn't seem to have moved enough in several hours to support that, even as a long-term motion.


That was according to WWLTV at 08:57 this morning. Guess we shall see if it's true.
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Quoting CloudGatherer:
First, the good news. The Sewerage and Water Board reports that it is "confident" that the Army Corps' failure to remotely start the 17th Street Canal pumps won't have a material impact on flooding. They insist there's still capacity within the canal, and that they can go on pumping water out of the streets and into the canal. On the other hand, the Corps has asked them to slow down - and I frankly don't trust the S&WB to have a firm grasp of the situation. The key here is for the Corps to get all of its pumps started manually, since the remote systems have failed. They're apparently working on it.

Now, the bad news. The NYT's John Schwartz (@jswatz) is tweeting live from the operations center. He reports that "Water levels have risen in the 17th St. canal to maximum height for safety, though some are questioning the gauge readings." The Colonel in command of the district and Sen. Vitter are headed over to inspect the scene in person. Some pumps are coming online, but workers have to labor in genuinely treacherous conditions.

And then there's this pic, posted minutes ago to Twitter, with the caption, "this is 17th street canal just taken where pumps are and breach in 05 was." Hoping it's a fake, recycled from '05. Fearing otherwise.


we'll see if that $14.5 billion in levee upgrades was worth it soon. imgops is a good resource for checking a pic's validation.
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The Weather channel Live stream
Link
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1765. angiest
Quoting Asrock:
75MPH winds
moving NW at 6
pressure 972


It doesn't seem to have moved enough in several hours to support that, even as a long-term motion.
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Quoting guygee:
That is not redneck, it is smart. Break out of the stupid political stereotypes that are pushed onto us to keep us apart, get together with your neighbors and organize.



So sorry and excuse me! My neighbors are rednecks and will proudly tell you so! A person can be cajun, and a person can be redneck. Around here it depends on where you live, not how you live or whether or not you have a college degree.

Sorry, I rarely get annoyed, but...
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Quoting alaina1085:

I dont understand people who are under a mandatory evacuation, but choose to stay! This area always floods.


This was addressed rather well in an earlier post by someone that I can't find atm. The jist is, walk a mile in their shoes...
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Quoting CloudGatherer:
First, the good news. The Sewerage and Water Board reports that it is "confident" that the Army Corps' failure to remotely start the 17th Street Canal pumps won't have a material impact on flooding. They insist there's still capacity within the canal, and that they can go on pumping water out of the streets and into the canal. On the other hand, the Corps has asked them to slow down - and I frankly don't trust the S&WB to have a firm grasp of the situation. The key here is for the Corps to get all of its pumps started manually, since the remote systems have failed. They're apparently working on it.

Now, the bad news. The NYT's John Schwartz (@jswatz) is tweeting live from the operations center. He reports that "Water levels have risen in the 17th St. canal to maximum height for safety, though some are questioning the gauge readings." The Colonel in command of the district and Sen. Vitter are headed over to inspect the scene in person. Some pumps are coming online, but workers have to labor in genuinely treacherous conditions.

And then there's this pic, posted minutes ago to Twitter, with the caption, "this is 17th street canal just taken where pumps are and breach in 05 was." Hoping it's a fake, recycled from '05. Fearing otherwise.



if it breaches it will be small and contained...this isnt going to get out of control if this gets an inch or so above the bank, and the corps of engineers is starting the pumps anyway sometime so
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1760. Asrock
75MPH winds
moving NW at 6
pressure 972
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1759. LargoFl
BRAITHWAITE, La. -- Rescue workers are trying to get residents out of harm's way are who stuck in parts of lower Plaquemines Parish. President Billy Nungesser said that the town of Braithwaite is being inundated with 10-12 feet of water, with Hurricane Isaac chasing those that stayed behind to their attics and rooftops seeking high ground as they scramble to get out the parish.

Nungesser said it is unclear if a back levee was overtopped or if it was breached. "This is not a category-1 (storm), I don't care what anybody says," he said. "This rain, this driving wind. I got more damage to my house than I had for Katrina."

The area from Braithwaite to White Ditch was swamped with floodwaters after Hurricane Isaac came roaring ashore.

Rescue efforts are ongoing for residents, said Nungesser, but conditions are making it difficult to coordinate the rescues. Shrimp boats are being used to rescue people by picking people off rooftoops and take them safety.

One Braithwaite resident, Gene Oddo, talked with WWL-TV as he rode out the storm in the attic with his wife and infant daughter. Oddo said he got trapped in the attic after the water came quickly.

"It came up so fast," said Oddo over the phone, adding that some neighbors were also trapped in the area.

Nungesser said there is a report of a woman stranded on a rooftoop, and some people are stranded at the ferry landing. Nungesser said two pump operators were stuck on the levee in Braithwaite because the water came up too fast.

A tweet from CNN stated that three people were rescued from Plaquemines, according to Nungesser, including one woman from a rooftop.

The area, which is not part of the hurricane protection system, has dealt with flooding problems during serious storms before.

Nungesser said they're trying to get people out through St. Bernard.

"The water is going across the road pretty good. A minute ago they stopped moving people because they were fearful that they'd drive their cars off the road."

Nungesser said the area is seeing worst conditions than in Hurricane Gustav.

"If this is going to keep up for 36 hours, we're going to see that east bank area inundated with water."

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1758. FOREX
Quoting TropicalAnalystwx13:
Model runs for 98L are too far east...watch them shift west over the coming runs.

This is exactly how Isaac's early model runs looked and we see how that turned out.

Anyways, with Isaac making landfall on the Central Gulf Coast, we'll have another one either next month or October. They always come in pairs...Katrina/Rita...Gustav/Ike.

There are probably more.


Does steering ahead of it show a more Westward track you think?
Member Since: August 17, 2011 Posts: 0 Comments: 2335
@NWSNewOrleans: Rainfall totals climbing quickly......Lakefront Airport 9.03, New Orleans Int'l 3.75, Slidell 2.49, Audubon 8.10.
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The 600 lb gorilla in the room is that if this storm was the intensity predicted, we'd have several more overtopped levees, even with the post Katrina upgrades. The pumps have been awesome so far, though.
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Quoting emcf30:



I dont understand people who are under a mandatory evacuation, but choose to stay! This area always floods.
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Quoting ncstorm:
21 minutes ago from the web..from someone's roof in Braithwaite


Hurricane Isaac was perfectly situated to send a surge up the Mississippi River last night and it overtopped the levees on the Eastbank in Plaquemines Parish and flooded the Braithewaite community to a depth of 10 feet overnight.

Many homes are underwater, with residents trapped in their attics, ready to break through to their roofs.


All kidding aside. A sobering moment. It looks like there's people dying out there...
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1753. emcf30
Quoting slavicthunder:
Emergency situation in Braithwaite right now. The video footage shows water up to the roofs.


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ultimate.test.for.them.pumps
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1751. guygee
Quoting aislinnpaps:

After Rita we had a carload of teens drive down my deadend road with no lights at about 2 in the morning. They parked in the center of the only three houses here and got out, planning on looting. My one neighbor has a relative who is mentally challenged and sleeps whenever he is tired (He has a little one room 'house' on their property). He was up and they scared him so he went into the main house and woke them to say there were people outside in the dark. Those teens were then met with shotguns when they were ten feet from my door and about the same at the other closer house. This is redneck country, you don't mess with them!
That is not redneck, it is smart. Break out of the stupid political stereotypes that are pushed onto us to keep us apart, get together with your neighbors and organize.
Member Since: Posts: Comments:
First, the good news. The Sewerage and Water Board reports that it is "confident" that the Army Corps' failure to remotely start the 17th Street Canal pumps won't have a material impact on flooding. They insist there's still capacity within the canal, and that they can go on pumping water out of the streets and into the canal. On the other hand, the Corps has asked them to slow down - and I frankly don't trust the S&WB to have a firm grasp of the situation. The key here is for the Corps to get all of its pumps started manually, since the remote systems have failed. They're apparently working on it.

Now, the bad news. The NYT's John Schwartz (@jswatz) is tweeting live from the operations center. He reports that "Water levels have risen in the 17th St. canal to maximum height for safety, though some are questioning the gauge readings." The Colonel in command of the district and Sen. Vitter are headed over to inspect the scene in person. Some pumps are coming online, but workers have to labor in genuinely treacherous conditions.

And then there's this pic, posted minutes ago to Twitter, with the caption, "this is 17th street canal just taken where pumps are and breach in 05 was." Hoping it's a fake, recycled from '05. Fearing otherwise.

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How are the oil rigs holding up?
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Storm Total Rain Estimates So Far

Member Since: August 19, 2005 Posts: 5 Comments: 5452
He just keeps moving west..... maybe another suprise from Mr. Isaac????
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1746. ncstorm
21 minutes ago from the web..from someone's roof in Braithwaite


Hurricane Isaac was perfectly situated to send a surge up the Mississippi River last night and it overtopped the levees on the Eastbank in Plaquemines Parish and flooded the Braithewaite community to a depth of 10 feet overnight.

Many homes are underwater, with residents trapped in their attics, ready to break through to their roofs.
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1745. dabirds
Quoting dartboardmodel:
Morning guys... hey I need some help to explain the models. When I pulled up the water vapor imagery of the Central United States, that's all i see is a bunch of dry air sweeping directly south from the plains making a head-on collision with Isaac. How in the world does Isaac turn North all the way up to midwest? What in the world am I missing??? I don't see anything in the water vapor imagery to confirm this predicted move to the north. I would greatly appreciate any hints/remarks.
Here in C IL the winds were NW Mon, NE yesterday, and supposed to be E today, changing to SE. I assume that means the high moved over us, and will begin allowing him N,NW as it moves away.
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Houma appears to be utterly stuck in the clear in the center of the eye. Would be pretty interesting to be there right now you could just go outside and sit for hours staring as the Hurricane moved around you on all sides.
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Quoting oracle28:


Physics lesson for you.

Chuck Norris doesn't do pushups, he pushes the Earth down.

LOL!!! Yes indeed!
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LOL!

I would say, methinks thou doest protest too much, but I refer myself to my own advice:

Know the storm and when to retreat!
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Quoting calkevin77:


Doesn't he know that only Chuck Norris does pushups in a hurricane? Jeez lol.


Physics lesson for you.

Chuck Norris doesn't do pushups, he pushes the Earth down.
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Quoting Thing342:
I think after the season ends, it will be reclassified to be a Category 2, along with Gordon being a Category 3 and adding an unnamed system.

No land, buoy, oil rig, or storm chaser observations support an upgrade to Category 2 hurricane status. Ernesto is debatable in that regard though. As for Gordon, T-numbers from SAB and TAFB never reached T5.5/117 mph, so it probably won't be upgraded. Lastly, when was this possible unnamed tropical storm and where?

I know a lot of people have been asking about it, but Beryl is not being upgraded to a hurricane in post-season.
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Quoting aislinnpaps:


After Rita we had a carload of teens drive down my deadend road with no lights at about 2 in the morning. They parked in the center of the only three houses here and got out, planning on looting. My one neighbor has a relative who is mentally challenged and sleeps whenever he is tired (He has a little one room 'house' on their property). He was up and they scared him so he went into the main house and woke them to say there were people outside in the dark. Those teens were then met with shotguns when they were ten feet from my door and about the same at the other closer house. This is redneck country, you don't mess with them!


I'm not total pro-gun ownership by any means...but it's things like this that show how awful it'd be if there were a complete ban. Certainly need to protect yourself at times like that...especially being law enforcement likely won't get there. Not wanting to stir debate at all, just saying!

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Emergency situation in Braithwaite right now. The video footage shows water up to the roofs.
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Quoting alaina1085:


Here's the pic I took... these dude is a joke.


Hey
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1734. KEEPEROFTHEGATE (Mod)
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Quoting SWLACajun:


NOT!!!!

Umm I am with you! He is no way shape or form appealing to these eyes!
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1732. Jaevyn
Quoting TomballTXPride:

Storms as large as this need a deep source of heat of which to tap into. The swampland can and will not provide this. He is beginning to fall apart as we speak, but that doesn't mean the conditions will be any better. Our classification system of TS or Hurricane is mad-made. Mother Nature goes by her own rules.


Storms as large as this can bring in energy from the parts that are still over ocean (which is at least 50% of it), and yes they can harness energy from swampy landscapes (Fay in 2009 is an example). While he is paralleling the coastline like this you wont see any significant weakening.
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Quoting mikatnight:


Not sure about that. Google "fish caught in fence". Supposedly it's...
"Fish remain stuck in a fence on September 15 as flood waters caused by Hurricane Ike recede, in West Orange, Texas
Picture: AP"


The mouth of the fish on the left is obviously manipulated. No doubt about it.
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Here's the pic I took... these dude is a joke.
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according to radar the eyewall looks to be collapsing... or at least getting much smaller of an eye
Member Since: August 1, 2006 Posts: 28 Comments: 3716
Quoting mikatnight:
Sounds like some of the ladies might nhave a bit of a crush on Mr. Cantore...
Cantore calenders on the wall perhaps?


NOT!!!!
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1727. Asrock
Quoting StormHype:


Now that is good. Fake obviously, but a clever, creative, and very funny pic! :-)


I remember that picture actually, it came out of Texas 7 or so years ago when they got slammed by a hurricane. There was one area that was heavly flood, that picture with the fish in the fence came from there. I remember it on CNN's aftermath slide show on their website. In fact I think it was Ike.
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1726. ncstorm
are they seriously talking about bacon?? AL and Jim are hilarious right now..
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Quoting reedzone:


Ur video is unavailable :/

Crap sorry guys, a friend posted it on FB thought it would work.
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1724. MahFL
Quoting vlaming:


How about they will retire it because people in Haiti and the Dominican died?

Those countries would have to formally ask for the name to be retired to do that.
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His only weak spot is on his northwest side. You can even seem once again reforming his southern eye wall over water. Just by looking at radar this storm is not weakening significantly or maybe at all for that matter.

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Quoting reedzone:
Looks like Isaac has lived up to its reputation.. I personally believe the storm became a Category 2 last night as winds gusts reported around 120 mph in some areas. I don't believe a Category 1 can produce that much wind. Anyways, awkward to believe this is happening 7 years ago after Hurricane Katrina.. Just odd.
"7" is a Biblical number!
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1720. jpsb
Quoting Jaevyn:


That is unlikely to happen, while Isaac is technically over land, this land is swampy. That and I cannot see any evidence of any significantly warming cloud tops.
Someone with detailed knowledge of La swamp/marsh land pointed out yesterday the Issac intensified over land, reason being that the swamp/march land is really just hot shallow water.
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Quoting alaina1085:
img src="">
Unbelievable...

Can't see it.
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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.