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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Quoting kctinney:


Could you please answer my question then that I have posed (now) 3 times? TIA

What is everyone's feelings on the dam breaking and the manual breaching of it...........I'm afraid they will end up making it break and flood d/t pressure from water built up against it............plus aren't they still getting rain?



Well, I have read what the news is saying, but it makes not much sense to me.
I don't know the area....

Sounds like they are trying to save a bad situation.
If the dam goes, there will be flash flooding.
If they let the water out slowly, there will be flooding but it will be less severe.

That's my take...
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Quoting Chicklit:

You put quite a zinger together yourself.
zing!


ba- zing -a back at cha
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Quoting TropicalAnalystwx13:

*passes insult to Joe Bastardi*

At least the information I put out is useful and makes sense.

zing!
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Quoting TropicalAnalystwx13:

*passes insult to Joe Bastardi*

At least the information I put out is useful and makes sense.


Exactly. Unlike Bastardi, you are helping the human race.

Quoting AstroHurricane001:


How insolent. This is what it should say:

In 2012, Bastardi made a forecast based on the Madden-Julian Oscillation, predicting "drought-busting rains" to occur in the American Midwest and the Ohio Valley in June. In reality, drought intensified over those regions in June, what the heck, this script deleted my information.[citation needed]

rather -->


I'll go fix that if you want. The last part though is true, if as blunt as a hammer.
Member Since: October 4, 2007 Posts: 0 Comments: 450
Quoting TropicalAnalystwx13:

*passes insult to Joe Bastardi*

At least the information I put out is useful and makes sense.



When you can make a living at it..then I'll take you
seriously.
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Quoting serialteg:

Stay on the microwave, I think the MW is the best portent, first to depict stack and direction. Vital signs, so to speak.
Member Since: August 4, 2007 Posts: 0 Comments: 2798
Quoting PensacolaDoug:
I'd like to see you bashers try to make a living at ultra-long range forecasting. No-one else really goes out on a limb like he does. It's a very daunting job.


And with "ultra-long range forecasting" comes big errors, as weather is extremely unpredictable.

Let's be real. Meteorology is a science.. nothing is set in stone even when models and professional degrees are involved.

Accuracy and precision are key in the field.
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Quoting muddertracker:


rofl...priceless.

You put quite a zinger together yourself.
zing!
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Quoting CASANOVA7823:


Thanks PRweathercenter.
Anytime GIfs are the only images that i can view on my device
Member Since: July 21, 2010 Posts: 60 Comments: 1011
Quoting TropicalAnalystwx13:

*passes insult to Joe Bastardi*

At least the information I put out is useful and makes sense.


Could you please answer my question then that I have posed (now) 3 times? TIA

What is everyone's feelings on the dam breaking and the manual breaching of it...........I'm afraid they will end up making it break and flood d/t pressure from water built up against it............plus aren't they still getting rain?

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Quoting TomTaylor:
He also insisted many times that the east US would see a flip to a big winter last year. Never really happened. He also anticipated a cool summer over the midwest in late spring and summer. Ended up horribly wrong there.

The point is Joe is too aggressive and tries too hard to make the big forecast.


He's made some great calls from long ways out as well. That's why he is respected in his field.
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Quoting TomTaylor:
ouch!

Felt that one all the way out in San Diego


So that's what woke you up.
Member Since: July 17, 2009 Posts: 63 Comments: 23710
Quoting Grothar:


As quoted by someone with 20,939 comments LOL

*passes insult to Joe Bastardi*

At least the information I put out is useful and makes sense.
Member Since: July 6, 2010 Posts: 108 Comments: 30251
I'd like to see you bashers try to make a living at ultra-long range forecasting. No-one else really goes out on a limb like he does. It's a very daunting job.
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Storm chaser Brett Adair will be on the Barometer Bob show soon. http://hurricanehollow.org/
Member Since: September 30, 2007 Posts: 9 Comments: 15749
Was just looking at the GFS runs off of Africa. Could be an interesting couple of weeks ahead.
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Quoting PensacolaDoug:


I don't know whether your statement is true or not. Since when is a meteorolgist not allowed to be wrong? Happens to the best of them. Seems like you're holding him to a different standard than all of the rest.
He also insisted many times that the east US would see a flip to a big winter last year. Never really happened. He also anticipated a cool summer over the midwest in late spring and summer. Ended up horribly wrong there.

The point is Joe is too aggressive and tries too hard to make the big forecast.
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Quoting HrDelta:


He is someone so incompetant, he was let go. That is an achievement.

And this little Nugget from Wikipedia:

In 2012, Bastardi invoked the Madden-Julian Oscillation to predict that "drought-busting rains" would occur in the midwest/Ohio valley in June. That was the exact opposite of what actually occurred.


How insolent. This is what it should say:

In 2012, Bastardi made a forecast based on the Madden-Julian Oscillation, predicting "drought-busting rains" to occur in the American Midwest and the Ohio Valley in June. In reality, drought intensified over those regions in June, what the heck, this script deleted my information.[citation needed]

rather -->
Member Since: August 30, 2008 Posts: 8 Comments: 2834
Isaac is gonna ruin Labor Day Weekend.
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Quoting MAweatherboy1:
SHIPS does not indicate a particularly favorable environment ahead for Leslie- moderate wind shear of 10-20kts, and somewhat dry air... this could keep her a little weaker and possibly steer her more west. The SHIPS itself takes her to 88kts. I'm still seeing a recurve as the likely scenario, but it wouldn't surprise me if the models trended west some and brought her very close to Bermuda.


ships was so far off in isaac that im :yaoming:'ing it
Member Since: August 22, 2006 Posts: 2 Comments: 1975
Quoting Chicklit:
Here is Joe Bastardi in a nutshell.

By the way, this is from a blog called Bad Science.


rofl...priceless.
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Ok, will try again,

What is everyone's feelings on the dam breaking and the manual breaching of it...........I'm afraid they will end up making it break and flood d/t pressure from water built up against it............plus aren't they still getting rain?
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Quoting AstroHurricane001:
Interesting.

And it will get more interesting. Tropics will be active and severe weather outbreaks shall return.
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Quoting stormpetrol:


Not sure pot, there is no denying as for now its headed due west! By this time so tomorrow we will have a better idea.

True, that.

Temps maxed out at 95F at noon, with heat index 107, here.
No breeze at all.

In the afternoon, big rumbles and grumbles out over the gulf to the west.
Major heat, broke the record for the date, last set in 1999.
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Quoting Grothar:


Anytime someone writes a word with more than two syllables I am always impressed. I already gave them a plus for that one.


"syllables" has three!
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Quoting PensacolaDoug:
All of you Bastardi Bashers? He's respected among meteorologists. You guys couldn't carry his briefcase.


Thank you Pensacola, well said. On top of that, most here couldn't carry his briefcase filled with the 6 figure salary he had when he was at Accuweather. Probably still not doing too bad at Weatherbell.
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Here is Joe Bastardi in a nutshell.

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Quoting PensacolaDoug:
All of you Bastardi Bashers? He's respected among meteorologists. You guys couldn't carry his briefcase.

You got that right, if his ego is in that brief case I reckon the hulk couldn't lift it
Member Since: June 6, 2010 Posts: 0 Comments: 4371
most of us are probably better than him at forecasting.


Dumbest post of the year.
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Quoting Grothar:


As quoted by someone with 20,939 comments LOL
ouch!

Felt that one all the way out in San Diego
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Quoting NoloContendere:
Hopefully they'll bring you some cheese to go with that whine. Clearly you don't have enough self awareness to know when you're embarrassing yourself. I feel sorry for the EOC staff having to deal with self centered whiners like you when there are actual serious things to be dealt with.



You're right, I'm apparently a self centered whiner that served his country honorably in the United States Marine Corps for 8 years to protect the very freedoms we all enjoy in the US. The same self centered whiner who took an oath to defend and protect the Constitution of the United States of America. The same constitution that is the basis for our way of life. The one that established our form of government. The same government that we as citizens elect and pay taxes to. Just as I, the whiner, took an oath to uphold and defend the Constitution, our elected officials took an oath to serve their constituents. As such, I expect my elected officials to uphold their oath and not simply dismiss their constituents like you do so freely as whiners and not in need of basic services during a time of crisis.

And since I'm sure you'll come back with another witty retort like the last, I prefer Pepper Jack cheese.
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Quoting Hurricanes305:


Cantore is more of a Weather enthusiast than met and have a wide range of knowledge of tornadoes and severe weather where a majority of his respect is earn as well as being the first to volunteer to be in the middle of the storm I have tremendous respect for him in that regard. However I seen Bastardi nail tropical system from a far. His rants and extreme wishcasting has derail his significance in tropical forecasting. Over the years he has made emotions cloud his judgement which many people have done. While I see some maturation in Jim Cantore's meteorological process.


I like Cantore. Sometimes I think his "showmanship" gets in the way of his message. ie: "size does matter" quote. After that, I didn't hear anything he said about Isaac, I was laughing my *ss off. Just my opinion.
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Quoting AstroHurricane001:
Interesting.



In what way??
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Quoting HrDelta:


He is someone so incompetant, he was let go. That is an achievement.

And this little Nugget from Wikipedia:

In 2012, Bastardi invoked the Madden-Julian Oscillation to predict that "drought-busting rains" would occur in the midwest/Ohio valley in June. That was the exact opposite of what actually occurred.


I don't know whether your statement is true or not. Since when is a meteorolgist not allowed to be wrong? Happens to the best of them. Seems like you're holding him to a different standard than all of the rest.
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Quoting Grothar:
History of Leslie so far

13.5N 39.3W
13.9N 41.3W
13.8N 42.6W
14.2N 44.5W


So slightly North of due West.


well at that pace she could miss the islands *could
Member Since: August 22, 2006 Posts: 2 Comments: 1975
Quoting Hurricanes305:


He is like Jim Cantore but way more knowledgeable about the tropics.
He is a smart guy, but his overaggressive personality tends to hinder his reputation and credibility as a forecaster. In fact, Joe is probably better known for his aggressive, hype-ist, anti-NHC agenda than his ability to forecast the weather.
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Quoting pottery:

Looks ominising!
You think it will keep west all the way..???


Not sure pot, there is no denying as for now its headed due west! By this time so tomorrow we will have a better idea.
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Member Since: August 22, 2006 Posts: 2 Comments: 1975
History of Leslie so far

13.5N 39.3W
13.9N 41.3W
13.8N 42.6W
14.2N 44.5W


So slightly North of due West.
Member Since: July 17, 2009 Posts: 63 Comments: 23710
I imagine the NHC may go higher than 90 mph at 11pm EDT.

Member Since: July 6, 2010 Posts: 108 Comments: 30251
Quoting beell:


YW, SD.

I think it came over the very much depleted marsh between the Mississippi River and the Mississippi River Gulf Outlet Canal-but not certain.
OK. I see your thinking...


image credit: mrgo.gov

Thanks again.
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845. JLPR2
Quoting GeoffreyWPB:


As of 5:00 p.m....

THE INITIAL MOTION IS ABOUT 280/18. LESLIE SHOULD TURN TOWARD THE
WEST-NORTHWEST IN THE NEXT 12 HOURS OR SO AS IT MOVES AROUND THE
SOUTHWESTERN SIDE OF THE SUBTROPICAL RIDGE.



If the arc in the convection is really a partial eyewall it would mean the storm is at 14n, the NHC has it at 14.5n, in other words it would be a pure west motion or 270.
Member Since: September 4, 2007 Posts: 7 Comments: 8459
All of you Bastardi Bashers? He's respected among meteorologists. You guys couldn't carry his briefcase.
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Quoting Grothar:




Come on tell us what you really think! LOL

It's OK, TropicalAnalyst and I have been good friends for years. We spend most of the time insulting each other. That's what friends do!


Oh, I know. I was just finding a way to bash Bastardi. Essentially, most of us are probably better than him at forecasting.

The only thing he should be forecasting is the number of burgers to be made, or the amount of trash cans he will deal with today. Unfortunately, some news stations like to consult the mentally unfit on very complicated matters, such as weather and climate.
Member Since: October 4, 2007 Posts: 0 Comments: 450
Quoting hydrus:
How do you know that Bastardi knows more about the tropics than Cantori.? What are you basing that statement on.?


Cantore is more of a Weather enthusiast than met and have a wide range of knowledge of tornadoes and severe weather where a majority of his respect is earn as well as being the first to volunteer to be in the middle of the storm I have tremendous respect for him in that regard. However I seen Bastardi nail tropical system from a far. His rants and extreme wishcasting has derail his significance in tropical forecasting. Over the years he has made emotions cloud his judgement which many people have done. While I see some maturation in Jim Cantore's meteorological process.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
Interesting.

Member Since: August 30, 2008 Posts: 8 Comments: 2834
SHIPS does not indicate a particularly favorable environment ahead for Leslie- moderate wind shear of 10-20kts, and somewhat dry air... this could keep her a little weaker and possibly steer her more west. The SHIPS itself takes her to 88kts. I'm still seeing a recurve as the likely scenario, but it wouldn't surprise me if the models trended west some and brought her very close to Bermuda.
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Partially due to let people know I'm still living, I just did a blog on the tropics.
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Quoting Charmeck:

Link or info - what - where???


799. Grothar 8:42 PM EDT on August 30, 2012
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About JeffMasters

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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