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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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: 3488
Quoting LargoFl:
i think i remember some folks in texas who were wishing for isaac's rains..maybe they will get it now if that happens


It would be nice. Unfortunately that model is not good with tropical storms so I give it a 5% chance of actually happening.
Member Since: August 18, 2011 Posts: 0 Comments: 635
Quoting keisa90:
For what it's worth, the new NAM now brings what's left of Isaac all the way to SE Texas before turning it northward.


Yes some models have been showing that. But no one seems to think that will happen. NWS said SETX would be on the western fringe of the storm. Gusty winds maybe 1-2 inches of rain.
Member Since: August 24, 2010 Posts: 0 Comments: 252
Thoughts and prayers are going out to those being affected by Isaac. Needs to hurry on through.

Back to lurking.
Member Since: Posts: Comments:
2015. JasonRE
Quoting hurricanehanna:

Jason...dry air has been feeding in from the west so we aren't getting the rainbands we normally do. Gustier winds and the rain will be picking up later this afternoon and will linger into tomorrow. It is moving sloooowly :(


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....
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Member Since: Posts: Comments:
2013. Asta
Quoting MoldyinMS:


Nobody and I mean nobody has more compassion and respect for first responders than I do, I was making a point that some people do not have the resources to evacuate every storm. I don't presume to judge. Evacuation centers are not always a solution. Circumstances are different for everyone. Could be health, maybe you can't leave a relative, whatever. Its not always a black and white issue.


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..
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2012. IMA
Quoting BeanTech:


You left out:

foot fetish
goddess
"Good Sir"


hot towers
pin-hole eye
lol It goes on & on
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2011. LargoFl
Quoting keisa90:
For what it's worth, the new NAM now brings what's left of Isaac all the way to SE Texas before turning it northward.
i think i remember some folks in texas who were wishing for isaac's rains..maybe they will get it now if that happens
Member Since: Posts: Comments:
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 AtHomeInTX:


Lol. I talk out loud to the blog sometimes. My husband just shakes his head. What's really bad is that now HE knows about people on the blog. :)
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
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Quoting Charmeck:


You want compassion - where is the compassion for the people that have to go out and rescue them?? My heart and prayers go out to everyone - victims and rescue personnel but when evacuations are ordered there is a reason and usually there are evacuation centers that you can go to.


I too have compassion for both victims and rescuers, but have no doubts, most of the rescuers live for their jobs and would rather be doing nothing else. They love what they're doing.
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Quoting JasonRE:
Is this thing moving West at all like some of the models suggested? Our local Mets are saying that it's still uncertain if it will run up LA as it shows. Also, still haven't seen much rain. What's up with that? Could the nasty stuff start tonight and go into tomorrow?

Jason...dry air has been feeding in from the west so we aren't getting the rainbands we normally do. Gustier winds and the rain will be picking up later this afternoon and will linger into tomorrow. It is moving sloooowly :(
Member Since: September 5, 2007 Posts: 0 Comments: 3488
2006. keisa90
For what it's worth, the new NAM now brings what's left of Isaac all the way to SE Texas before turning it northward.
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2005. Asta
The water came up very quickly this time..
Interview with BIlly Nunguesser here.
http://www.npr.org/blogs/thetwo-way/2012/08/29/16 0233986/plaquemine-parish-president-damage-is-just -as-bad-as-katrina

The water is coming up on Three Rivers Road in Mandeville as well photos here
http://www.wwltv.com/

We have at least another day of rain and storm surge..
Loks like Isaac is another "Ms. Mousey" storm.. just sits and spins...
Not good. not good at all.
I'm worried about those in St. Charles Parish right now...
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2004. MTWX
Quoting jpsb:
From experience, been thru many TCs. If the storm is bad you will NOT be allowed back. All your stuff is sitting unprotected in an area WITHOUT effective law enforcement. How would you like you leave all your stuff sitting around unprotected and not be allowed back for many days after the storm? Not me, I stay.


Stuff can be replaced... your lives cannot!!
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Quoting Charmeck:


You want compassion - where is the compassion for the people that have to go out and rescue them?? My heart and prayers go out to everyone - victims and rescue personnel but when evacuations are ordered there is a reason and usually there are evacuation centers that you can go to.


Nobody and I mean nobody has more compassion and respect for first responders than I do, I was making a point that some people do not have the resources to evacuate every storm. I don't presume to judge. Evacuation centers are not always a solution. Circumstances are different for everyone. Could be health, maybe you can't leave a relative, whatever. Its not always a black and white issue.
Member Since: Posts: Comments:
For our Houstonians...

Ananometer at 68' (on a sailboat mast) in Seabrook. Winds consistent 18kt from 340 with gusts to 25kts. Water dropping in the bay. Oh, and HOT.
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2000. JasonRE
Is this thing moving West at all like some of the models suggested? Our local Mets are saying that it's still uncertain if it will run up LA as it shows. Also, still haven't seen much rain. What's up with that? Could the nasty stuff start tonight and go into tomorrow?
Member Since: Posts: Comments:
Quoting ringeaux:


Also:

Blob
Wobble
RI RI RI
and I see an eye-wall

and let's not forget the almight POOF!
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Quoting ringeaux:


Also:

Blob
Wobble
RI RI RI
and I see an eye-wall


An eye wall?

I thought it was an eyeball????

Member Since: Posts: Comments:
Quoting RitaEvac:
Houma in the middle



Finally moving. Step on the gas already Isaac.
Member Since: August 24, 2010 Posts: 0 Comments: 252
Watching the loops from while I was sleeping -- thing really blew up again right before it hit. I really hope folks are as ok as possible. Nothing but good thoughts to all.

What a night for new puppies. Hope Pat, Nola Roux, and the kids are fine. Later when we need some levity I hope he posts lots of pics. I have a feeling we'll all be needing something happy.

Looks like pretty massive flooding basically from south LA all the way over into AL and MI -- are the bulk of the photos from surge? The rain with this thing is no joke, either, so I can't imagine there aren't at least some smaller floods well inland, too.
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Quoting AtHomeInTX:


Lol. I talk out loud to the blog sometimes. My husband just shakes his head. What's really bad is that now HE knows about people on the blog. :)

lol we were discussing Pat's puppies last night and my family was enjoying the pics !
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Quoting angiest:


Annular hurricane


Fujiwara!
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1992. jpsb
Quoting Charmeck:


You want compassion - where is the compassion for the people that have to go out and rescue them?? My heart and prayers go out to everyone - victims and rescue personnel but when evacuations are ordered there is a reason and usually there are evacuation centers that you can go to.
From experience, been thru many TCs. If the storm is bad you will NOT be allowed back. All your stuff is sitting unprotected in an area WITHOUT effective law enforcement. How would you like you leave all your stuff sitting around unprotected and not be allowed back for many days after the storm? Not me, I stay.
Member Since: Posts: Comments:
1991. angiest
Quoting ringeaux:


Also:

Blob
Wobble
RI RI RI
and I see an eye-wall


Annular hurricane
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting ironbanks:
On generator power. Terrible Cat 1 imo. Large tree down in yard hitting neighbors house. I will try and get a pic up. Very worried about the amount of rain to fall over next 24 hrs.


Stay safe first...

This is what we were discussing yesterday morning on he blog. A bad senecio where a storm moves slow/stalls and is to the west of Nola/MS/AL.
Member Since: Posts: Comments:
1989. 7544
wow hy90 in biloxi under water up to the traffic lights looks like a river
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Houma in the middle

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Quoting FrancesJeanne:

13. You find yourself laughing out loud and nodding your head in agreement with every single point on this list - well said and too funny!


Lol. I talk out loud to the blog sometimes. My husband just shakes his head. What's really bad is that now HE knows about people on the blog. :)
Member Since: August 24, 2010 Posts: 0 Comments: 252
Quoting oracle28:


Dont forget the phrases

DOOM
shower curtain
pinhole eye
bottom-out
fish storm


Also:

Blob
Wobble
RI RI RI
and I see an eye-wall
Member Since: Posts: Comments:
1985. 4waters
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.


yup. all of it.
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.


The funniest blog entery yet... And also true dat....
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On generator power. Terrible Cat 1 imo. Large tree down in yard hitting neighbors house. I will try and get a pic up. Very worried about the amount of rain to fall over next 24 hrs.
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Quoting dogsgomoo:
Now, I'm not saying that the NHC should have designated him a Cat 1 when he was still off the Keys. But I do think the generalized dismissal of 'Tropical Storms' causes a lot of problems and misunderstandings. The IKE scale needs to be used and I also think that the term Tropical Storm needs to be phased out and replaced with Cat 0 Hurricane.

Or call them all tropical storm/cyclones/hurricanes without the SS "cat" rating. Size/Surge/Winds/Forward Speed should all be rated with the highest number or an average being used.

Thus, Isaac could have been a cat 3/3/1/5. So he could have been a "Cat 3" tropical storm, or something like that. But since he's in progress I'll quit now. :p
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1981. hendric
Here's a pretty cool website:

http://hint.fm/wind/

Check out that eye!
Member Since: Posts: Comments:
1980. Asta
Quoting Carnoustie:

no,one levee which is over topping not breaching.

Billy Nunguesser is on Radio now.. He just said that they ARE breeched..
Talking with John Snell
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Quoting KRL:
Wow. Talk about the height of stupidity.




Future Darwin award winners.
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outermost rainband starting to reach here now...some really good gusts upwards of 45 mph. Could be higher but I'm bad at guessing.
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Sorry for the double post.
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.

13. You find yourself laughing out loud and nodding your head in agreement with every single point on this list - well said and too funny!
Member Since: Posts: Comments:
Quoting Masquer08er:
Causeway in Mobile AL via WKRG TV

thats the old oyster house isnt it?
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Quoting LostTomorrows:


But she raced across that stretch of land like nobody's business. She was there and gone in a matter of a few hours.


Very true...........This is a nightmare flooding scenario. We have consistently seen slow moving tropical storms/minimal hurricanes cause more damage from surge/rainfall than faster moving lower end hurricanes caught up in moving trof.
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Quoting LostTomorrows:


But she raced across that stretch of land like nobody's business. She was there and gone in a matter of a few hours.


Thank God.
Member Since: August 24, 2010 Posts: 0 Comments: 252
1972. K8eCane
Quoting DVSmith:


Arthur, Bertha and Fran all came ashore at Cape Fear in 1996 (I was living on Oak Island at the time).

Arthur was a TS, Bertha a Cat 1, which had stalled off SC and weakened from a Cat 2, before zipping up the eastern part of the state. Fran slammed ashore as a strong Cat 3 and was still a decent Cat 2 when it went through Durham.

Bonnie, in 1998, made landfall at Cape Fear as a Cat 3 and barely moved, dropping down to a TS, before curving back out to sea as a weak Cat 1 (having strengthened over the sounds).



i was here and home for all the above but didnt realize bonnie was cat 3. she didnt feel as strong as fran
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1971. unc70
Quoting GetReal:
I believed that someone already mentioned this already, but when this is over with I hope the NHC reviews the data from the local reporting stations. I am very confident that this morning between 0200-0400 hours, we were experiencing sustained winds of 100 mph...

I was here also for Katrina and saw nearly the same bowing of trees. The only difference is those type winds lasted about 4 hours.


When Irene hit NC last year, every one of the official stations stopped reporting 2-5 hours before landfall! We had a few State of NC stations still reporting through RAWS, but they are not up to NHC standards. Also a couple of PWS using radio links. And OZ steaming video from the eye, though 20-30 miles from the official coords for the eye.
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Quoting chrisucf:


Best comment so far on this blog.


This is so awesome!!!! LOL
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Quoting MisipiGrl:
Wind gust from Long Beach, MS (Univ. of Southern Miss on Wunderground) of 95.5 mph. I was just down there. Felt like wind was picking up
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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.

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