Isaac slamming Gulf Coast with damaging floods, tornadoes

By: Dr. Jeff Masters , 4:44 PM GMT on August 30, 2012

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Slow-moving Tropical Storm Isaac continues to hammer coastal Louisiana, Mississippi, Alabama, and Florida's Panhandle with tornadoes, torrential rains, high winds, and a damaging storm surge. Over the past 24 hours, destructive tornadoes have touched down in Biloxi and Pascagoula, Mississippi, and one person was killed by a tree falling on a car in Pearl River County, Mississippi. A major flood event is occurring in Slidell, Louisiana, where Isaac's storm surge filled Bayou Bonfouca and the W-14 Canal, inundating portions of the city with 1 - 5 feet of water. While Isaac is now a weakening minimal-strength tropical storm, it is still a potent rainmaker, and will cause damaging floods all along its path for the next three days. Major river flooding is occurring or is about to occur on a number of rivers in the landfall area. In north central Tangipahoa Parish in southeast Louisiana and southwestern Pike County in southern Mississippi, a mandatory evacuation has been ordered for all low-lying areas and along the Tangipahoa River, due to the potential failure of the Lake Tangipahoa dam. Audubon Park in New Orleans, recorded 11.19" of rain as of 7 pm Wednesday night. An earlier amount of 19" was found to be erroneous, and this is not a 24-hour precipitation record for the city. According to wunderground's weather historian, Christopher C. Burt, New Orleans' greatest 24-hour rainfall on record is 14.01" on July 24 - 25, 1933. The Louisiana official state 24-hour record is 22.00" on Aug. 29, 1962 at Hakberry, although U.S. Army Corps of Engineers `Storm Studies' mentions a 23.80" falling in a 24-hour period at Millers Island during a TS on Aug 7-8, 1940. Storm total was 37.50" over a 60-hour period there during that event.

A few other rainfall totals from Isaac, through 11 am EDT on Thursday:

15.02" Marion, MS
10.09" Hattiesburg, MS
10.15" Gulfport, MS
9.80" Slidell, LA
9.74" Biloxi, MS
8.52" Mobile, AL
5.57" Baton Rouge, LA


Figure 1. Isaac's winds and storm surge overcomes the seawall and floods South Beach Boulevard in Waveland, Miss., Wednesday, Aug. 29, 2012, the seventh anniversary of Hurricane Katrina hitting the Gulf Coast. (AP Photo/Rogelio V. Solis). Waveland experienced a storm surge in excess of 5' for 36 hours.

Isaac's storm surge winds down
Storm surge levels along the coast of Mississippi and surrounding areas are gradually receding, and the surge has finally fallen below 5' at Waveland, which experienced a storm surge in excess of 5' for 36 hours. Isaac's storm surge levels were characteristic of a Category 2 hurricane, and lasted for an exceptionally long period of time. Waveland, Mississippi experienced a peak surge of 8' and peak storm tide of 9' (surge plus the natural high tide), which beat the levels that occurred during Category 2 Hurricane Gustav of 2008 (7' of storm tide.) The peak 11.06' storm surge at Shell Beach, which is in Lake Borgne, 30 miles southeast of New Orleans, exceeded the 9.5' surge recorded there during Gustav. According to an article in nola.com, Isaac pushed a storm surge of 13.6' into Lake Borgne, on the east side of New Orleans. This is not far from the 15.5' storm surge Hurricane Katrina brought to the location. It is quite possible that Isaac's storm surge might have breached levees of the east side of New Orleans, flooding areas inhabited by tens of thousands of people, had the Army Corps of Engineers not completed their $14.5 billion upgrade to the New Orleans flood defenses this year. I estimate that storm surge damage from Isaac will exceed $2 billion. Isaac has likely caused $2.5 billion in insured damage not related to flooding, insurance firm Eqecat estimated yesterday. Here were some of the peak storm surge values that were recorded at NOAA tide gauges during Isaac:

11.1' Shell Beach, LA
8.0' Waveland, MS
3.5' Pensacola, FL
4.6' Pascagoula, MS
3.8' Mobile, AL


Figure 2. A TRMM satellite 3-D view of rainfall on Aug. 28 showed a few very powerful thunderstorms near Isaac's eye were reaching heights of almost 17 km (10.6 miles.) Intense bands of rain around Isaac were occasionally dropping rain at a rate of over 2.75 inches per hour. Image credit: SSAI/NASA, Hal Pierce.

Isaac's storm surge on the Mississippi River
A storm surge estimated at 12' moved up the Mississippi in Plaquemines Parish near Port Sulphur, LA, near 8:30 pm EDT Tuesday, causing overtopping of the levees and flooding of homes in the mandatory evacuation areas behind the levees. These levees were not part of the $14.5 billion levee upgrade New Orleans got after Hurricane Katrina, and were not rated to Category 3 hurricane strength, like the levees protecting New Orleans are. Since salt water is more dense than fresh water, the surge travelled along the bottom of the river, with the fresh water flow of the river lying on top. The surge continued upriver, and before reaching New Orleans, encountered an underwater barrier in Plaquemines Parish. This barrier was constructed by the Army Corps of Engineers beginning on August 15, in order to keep salt water from moving upstream and contaminating drinking water for Plaquemines Parish and New Orleans. Salt water had made it 90 miles upriver to the outskirts of New Orleans, due to the low flow rate of the river (which had dropped 7' below average in height due to the drought of 2012.) According to a spokesperson for the National Weather Service River Forecast Office, this barrier was probably able to completely block the flow of salt water upriver due to Isaac's storm surge, and no salt water made it as far as New Orleans. However, the massive intrusion of ocean water into the river channel caused the mighty Mississippi's fresh water flow to back up for hundreds of miles. Water levels were elevated by 10' in New Orleans (103 miles upstream from the mouth of the Mississippi), 8' in Baton Rouge (228 miles upstream), and 1.4' at Knox Landing, an amazing 314 miles upstream.

Hurricane Kirk in the Central Atlantic
Hurricane Kirk intensified into a 75 mph Category 1 hurricane this morning, becoming the busy 2012 Atlantic hurricane season's fifth hurricane. With the season's mid-point of September 10 still almost 2 weeks away, we've already had 12 named storms and 5 hurricanes, which is close to what an entire season experiences in an average year (11 named storms and 6 hurricanes.) Kirk should stay well out to sea and not trouble any land areas.


Figure 3. Morning satellite image of Hurricane Kirk.

Tropical Storm Leslie forms in the Central Atlantic
Tropical Storm Leslie has formed in the Central Atlantic. Leslie's formation on August 30 puts 2012 in 2nd place for earliest formation date of the season's 12th storm. Only 1995 had an earlier formation date of the season's 12th storm. With records dating back to 1851, this year is only the second time 8 total storms have formed in August. The other year was 2004, when the first storm of the season formed on August 1 (Alex), and the 8th storm (Hermine)
formed on August 29th. Leslie is organizing quickly, and appears destined to become a hurricane before the week is out. Fortunately, Hurricane Kirk is weakening the ridge of high pressure to the north of Leslie, and Leslie is expected to turn to the northwest and miss the Lesser Antilles Islands. In the long term, it remains unclear if Leslie will follow Kirk and fully recurve out to sea. The latest 2 runs of the GFS model have predicted that Leslie will recurve out to sea and not threaten any land areas, but the latest 2 runs of the ECMWF model have predicted that the trough of low pressure pulling Kirk to the northeast will not be strong enough to recurve Leslie out to sea. Instead, the ECMWF predicts that a ridge of high pressure will build in early next week, forcing Leslie more to the northwest, making the storm a potential threat to Bermuda, then to the Northeast U.S. and Canada in 8 - 11 days.

Jeff Masters

Hurricane Isaac Louisiana (apphotos)
Two men walk in the storm surge from Isaac, on Lakeshore Drive along Lake Pontchartrain, as the storm approaches landfall, in New Orleans, Tuesday, Aug. 28, 2012. (AP Photo/Gerald Herbert)
Hurricane Isaac Louisiana
west palm beach flood isaac (alishu)
West Palm Beach flood from Isaac
west palm beach flood isaac
Hurricane Isaac Impacts Navarre Beach & Pier10 (jennjeff1)
Hurricane Isaac versus Navarre Beach Pier, the longest concrete pier on the Gulf of Mexico
Hurricane Isaac Impacts Navarre Beach & Pier10

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The track and speed of Leslie is begining to be one of ooncern for the lesser antilles. IF the storm is at 50w and still south of 15n by tomorrow
morning then this could spell trouble for th islands.
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As I did write earlier, this is going to be a very large storm and I think perhaps stronger than a Cat 3.
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Quoting mobal:


It took the EOC 8 hours to get someone out here to assist them in getting fresh water.
Wow, since when is it the Govt. job to assist non prepared persons?


As some may know, I live in the UK, def not hurricane country...not even tornado or earthquake country. Ok, it is a bit of rain and wind country, and maybe cause I grew up in earthquake country, I am always prepared for 'something'. I live at the top of the hills, so not in a flood risk area (always avoid those if I can), 'can' get snow in the winter...but nothing like the northern US. I'm def not rich, I'm pretty poor at the moment from various circumstances...but I still manage to be prepared 'just in case'. So, I do have a hard time seeing people in a hazardous area not having enough supplies for 2 or 3 days. I have enough supplies for a few weeks, and I'm not anywhere hazardous compared to many places in the US. Maybe I'm just paranoid and they're optimistic!??!
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Quoting washingtonian115:
I personally want El nino so i can have a cold and snowy winter.

I want snow in PR.
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Quoting washingtonian115:
I personally want El nino so i can have a cold and snowy winter.

Yes!
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Quoting BahaHurican:
Latest it could have been was early '06, because by the main part of the season the term was in common use, and the debate over whether it counts as a fish storm if it hits Bermuda or the Azores was in high form. I expect to hear it at TWC... lol... I figure some of those guys blog as much as the rest of us... lol... But NHC... that would be mind-blowing... lol I wonder if anybody remembers a while back when somebody used "blob" in a discussion? This is why Grothar can say with authority, "blob" is a wx term... lol



If I give them permission they can use the term blob.
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Here's someone on another tropical weather discussion board using the term in reference to 2003's Isabel:

term

And in context, the user doesn't make it sound novel. IOW, its usage predates this forum, and is probably much older than that.

(And note the premature forecast: "I think that this one will be just a fish storm. In the NHC discussion, she is expected to turn to the WNW long before she gets to the Lesser Antilles due to a projected weakness of the upper level ridge. With it moving at just 13 mph, the ridge isn't strong enough to keep it on a westward track for long. IMO.". Of course, Isabel went on to become a 165-mph Cat 5 that made landfall in North Carolina, going to prove... ;-)
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Quoting washingtonian115:
I personally want El nino so i can have a cold and snowy winter.

No no no no for El Nino. It brings drier/warmer winters in MI and I need snow.
Member Since: March 16, 2012 Posts: 127 Comments: 7940
Wonder what Festus Haggin would think
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I personally want El nino so i can have a cold and snowy winter.
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Quoting JLPR2:


I'm almost convinced Leslie will move closer to the Lesser Antilles than predicted, being as stubborn as Earl, but not that close. If I remember correctly Earl also had a hurricane influencing its track which was Danielle.


Let's see when it reaches 50W if is north or south of 15N. That position is the barometer for the islands to be affected or not by a system.
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Quoting CaneGurl:


This was Louisiana, not Florida. Frankly, if you're in a flooded area, some cheesecloth and boiling time or bleach will give you all the fresh water you need, not to mention the water heater and the back of a toilet. It's also not that hard to fill a bathtub if you know a storm is coming, which will give you a supply of water for quite a while. It's really not the government's job to care of your every want (not need) when there are higher priority calls, like rescues and medical emergencies first in line. You've apparently never worked an EOC, getting hundreds of requests an hour from dozens of different agencies and the public, and then prioritizing them for response. It's not easy.
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Quoting TheHurricaneDundee:
Jeez both Kirk and Leslie are forcasted to become cat 2 hurricanes? I thought there was supposed to be an El Nino this year
The important thing at the moment is they are both apparently supposed to recure out to sea.. But I do like your handle
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Remember guys when I told you there were many people that thought there was a tornado in here and now its confirm there was one at least.
http://www.laprensa.hn/Secciones-Principales/Hond uras/La-Ceiba/Honduras-Un-tornado-causa-danos-y-pa nico-en-La-Ceiba#panel1-10
you can see it in there
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Quoting mobal:


If that’s the case then it was folly on their part. My point is that where you and I live we need to take responsibility into our own hands during these type of events. That and the fact that this country as a whole seems to think that the government should take care of them.


The point of my original post was the lack of information flowing from our officials regarding their response for recovery. I personally have plenty of supplies for an additional 3-5 days for me and my family. My neighbors, had they asked, could have used one of my cases of water I as part of my disaster kit. The point of the EOC portion of my message was they are saying one thing then doing something completely the opposite and that's what has people frustrated and wondering when if ever we are going to see relief out here.
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621. Relix
Quoting JLPR2:


I'm almost convinced Leslie will move closer to the Lesser Antilles than predicted, being as stubborn as Earl, but not that close. If I remember correctly Earl also had a hurricane influencing its track which was Danielle.


Fully agreed
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How can I obtain a satellite image loop for Leslie on my mobile device? Thanks..
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Quoting TheHurricaneDundee:
oh nothing nevermind
LOL..........I hear ya...........All is ok
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i joined in 06 but was lurking in 05. i believe it was stormtop that started using the term fish storm. with him, every storm was either gonna hit nola or was a fish storm. i wonder where he went
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I'm off until later... will check in closer to midnight, likely, to see what goes on with Mr. K and Ms. L...

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Quoting WxNerdVA:
Latest microwave of Kirk. Very small eye, bordering on pinhole, but the northwest eyewall was weak. It has been organizing since then though.





It has a very small eye because it's a very small hurricane. It wouldn't surprise me if Kirk in all reality gets way stronger than it's intensity is ever set to. This is because satellite estimates are known for underestimating the intensity of small hurricanes, and sense that's all that will be known for Kirk is satellite estimates, there would be know way to know for sure.

Kirk is about as small as Charley was.
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Quoting TheHurricaneDundee:
After Kirk and Leslie pass will the high in the atlantic restrengthen enough so that the next storm will not curve out to see?


Not a clue, and I don't think anyone else can give you more that a WAG.
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This was probably 10 am this morning center right at 14N
Member Since: April 29, 2007 Posts: 0 Comments: 7819
Moving at 21 MPH - It doesn't seem Leslie will be turning Northwest anytime soon. It would really have to slam on the brakes and take a sharp turn
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Quoting mobal:


It took the EOC 8+ hours to get someone out here to assist them in getting fresh water.
Wow, since when is it the Govt. job to assist non prepared persons?
Quoting mobal:


It took the EOC 8+ hours to get someone out here to assist them in getting fresh water.
Wow, since when is it the Govt. job to assist non prepared persons?

Give them and me a break! This area WAS prepared and inundated with rain since SUNDAY, been flooded since then also. Did you not see photos of FL cities floded? THINK about it... 5days of water useage. If no boat to get out, how do you expect them to get water, food or do you expect them to just do without?
Back to lurking
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Quoting StormDrain:
Baha,
fwiw, one of the mets on TWC called um, what's its name...? um, Kirk, a "fish storm" this morning. Wish I could remember who at wu coined that phrase. May have been leftty or Bob/weatherguy03 or someone posting on their blogs back in 2005.
Latest it could have been was early '06, because by the main part of the season the term was in common use, and the debate over whether it counts as a fish storm if it hits Bermuda or the Azores was in high form. I expect to hear it at TWC... lol... I figure some of those guys blog as much as the rest of us... lol... But NHC... that would be mind-blowing... lol I wonder if anybody remembers a while back when somebody used "blob" in a discussion? This is why Grothar can say with authority, "blob" is a wx term... lol

Quoting Skyepony:


I was posting back them but I heard the term as a kid growing up in east central FL.
Hmmm... Never heard it here in the Bahamas...
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Quoting TheHurricaneDundee:
After Kirk and Leslie pass will the high in the atlantic restrengthen enough so that the next storm will not curve out to see?
Why do you say that.....Give us all the facts.
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607. mobal
Quoting padirescu:


When they tell their citizens during a public news conference with the governor that if they need water, medical supplies, food, etc to call the EOC and they will get it to you quickly. Last I checked 8 hours wasn't the model definition of 'quickly'.


If that’s the case then it was folly on their part. My point is that where you and I live we need to take responsibility into our own hands during these type of events. That and the fact that this country as a whole seems to think that the government should take care of them.
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Quoting padirescu:


When they tell their citizens during a public news conference with the governor that if they need water, medical supplies, food, etc to call the EOC and they will get it to you quickly. Last I checked 8 hours wasn't the model definition of 'quickly'.


Another reason why politicians shouldn't be PIO's. No one from an EOC or EMA office would have promised to get people food and water as any kind of first priority. People have been known to live without both for more than 24 hours. There are also things called neighbors, relatives, friends, or local churches that are the appropriate places to request things like food and water, assuming that, for some reason, you were unable to supply your own needs for a day or so. As for medications, EOC's don't keep stocks of medications and would never promised to supply them. If you have a major medical emergency, the EOC will do all it can to help. Depending on the situation, eight hours can be a very fast repsonse time to a low priority call.
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Quoting Skyepony:


I was posting back them but I heard the term as a kid growing up in east central FL.


Skye,
Did you hear from your family you couldn't reach this morning?
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Quoting waterskiman:

LOL can't confirm this but I don't think they even closed.
I'm sure they didn't
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602. JLPR2
Quoting Gearsts:
Leslie missing the nhc track.


I'm almost convinced Leslie will move closer to the Lesser Antilles than predicted, being as stubborn as Earl, but not that close. If I remember correctly Earl also had a hurricane influencing its track which was Danielle.
Member Since: September 4, 2007 Posts: 7 Comments: 8655
Quoting PalmBeachWeather:
Looks like you need a brew at Dillons

LOL can't confirm this but I don't think they even closed.
Member Since: June 6, 2010 Posts: 0 Comments: 4429
nice post as always. one quibble-- the storm surge is the wave process, not the salt transport process, which is over a much smaller distance. the surge can propagate up a river, much further than the salt.

check my animations of Irene's salt transport versus surge and blog post at:
http://seaandskyny.com/2012/08/26/birds-eye-and-f ish-eye-views-of-irenes-floodwaters/

we also have a new published paper in Journal of Geophysical Research linked there on irene's surge and our modeling experiments.

Philip Orton,
Stevens Inst Tech
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Quoting mobal:


It took the EOC 8+ hours to get someone out here to assist them in getting fresh water.
Wow, since when is it the Govt. job to assist non prepared persons?
Lol, I don't even...
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Quoting JLPR2:


Kirk isn't supposed to exist according the models. XD The same thing happened with Florence.
They didn't pick up on T.D 7/Helene forming in the central atlantic either.
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Quoting Gearsts:
Leslie missing the nhc track.
Explain please
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Leslie missing the nhc track.
Member Since: August 2, 2010 Posts: 0 Comments: 1739
Quoting waterskiman:

Tavernier, MM92, we copped it here on the oceanside but no damage really. All the boats survived we kept power so it was all good.
Looks like you need a brew at Dillons
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Quoting CybrTeddy:
Eye becoming increasingly better defined in Kirk.
This is one beaut of a little storm...

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Quoting JLPR2:
The big picture.



Another one is getting ready to move into the Atl.

Dixie Isaac keeping it moist for the fall planting season, Leslie pondering Helene's route, being lured by the nanostorm almost on top of the Antilles, Kirk bored out of his skull, Central America trying to ante up a cyclone. Not a boring day in the tropics!
Member Since: August 4, 2007 Posts: 0 Comments: 3227
Quoting PalmBeachWeather:
Us here in Palm Beach county wasn't expecting the feeder band break off would sit over us for 24 hours.. Many areas are still flooded . waterski........Which key?

Tavernier, MM92, we copped it here on the oceanside but no damage really. All the boats survived we kept power so it was all good.
Member Since: June 6, 2010 Posts: 0 Comments: 4429
Quoting CybrTeddy:
Eye becoming increasingly better defined in Kirk.

I'd give 90 knots.
Member Since: July 6, 2010 Posts: 113 Comments: 31883
590. Skyepony (Mod)
Quoting StormDrain:
Baha,
fwiw, one of the mets on TWC called um, what's its name...? um, Kirk, a "fish storm" this morning. Wish I could remember who at wu coined that phrase. May have been leftty or Bob/weatherguy03 or someone posting on their blogs back in 2005.


I was posting back them but I heard the term as a kid growing up in east central FL.
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589. JLPR2
Quoting washingtonian115:
Models aren't picking up on that one..then again they weren't picking up on Kirk becoming a hurricane..


Kirk isn't supposed to exist according the models. XD The same thing happened with Florence.
Member Since: September 4, 2007 Posts: 7 Comments: 8655
Quoting flcanes:

man
Give that blogger a gold star.
;)
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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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