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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These past few days in Biloxi have seem like they have lasted a month. All is well in Biloxi, Hwy 90 is clear and the power is on.. I guess it is the price we citizen pay to live in paradise. Prayers go out to the people in Louisana that are flooding.
Member Since: Posts: Comments:
Quoting Tazmanian:

TWC is saying that 3 has died in LA THANKS TOO the I storm


One man died, a tow truck driver, I believe, when a tree fell on his truck. Two bodies were found in Braithwaite, in the flooding. :(
Member Since: August 22, 2009 Posts: 0 Comments: 3125
Quoting TomTaylor:
thanks taz, my bad lol



Welcome
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T.C.F.W.
12L/TC/L/CX
MARK
14.55N/46.91W
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TWC is saying that 3 has died in LA THANKS TOO the I storm
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983. WWPR
Quoting Tazmanian:
The L storm better start going wnw soon am looking foreword too how far W it gets overe night. It looks like its getting a little too close now


So am I. I'm still looking for that WNW curve.
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Quoting Jedkins01:


I'm not an Obama supporter, and I also don't think man came from apes.

There are more than 6 billion people in the world, living beings with many different views, so believe it or not, not everyone who is a scientist or scientific minded individual is an Obama supporter ;)


Reading me wrong, I didn't suggest that! I only noted Bastardi as I follow him on Twitter and I according to his tweets I understand how he thinks!
Member Since: April 29, 2007 Posts: 0 Comments: 7862
Kirk's eye has improved over the past several hours.

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Quoting stormchaser19:

Is west of the nhc track again.
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Quoting Tazmanian:



You got the storms mix up I think you mean the K storm we this got the L storm today
thanks taz, my bad lol
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Quoting TomTaylor:
Leslie sure has become an impressive storm. We are fortunate that this storm is out in the middle of the Atlantic and not a threat to land as our models did a horrible job with the intensity forecasts. NHC forecast reflects this, here was the intial forecast just two days ago


INIT 28/2100Z 23.8N 43.9W 30 KT 35 MPH
12H 29/0600Z 24.1N 45.3W 35 KT 40 MPH
24H 29/1800Z 24.3N 47.4W 35 KT 40 MPH
36H 30/0600Z 24.6N 49.6W 35 KT 40 MPH
48H 30/1800Z 25.3N 51.7W 35 KT 40 MPH
72H 31/1800Z 27.5N 55.5W 35 KT 40 MPH
96H 01/1800Z 32.5N 55.0W 35 KT 40 MPH
120H 02/1800Z 40.0N 48.0W 35 KT 40 MPH

FORECASTER BRENNAN

------

Now we have a strengthening 90MPH hurricane.



You got the storms mix up I think you mean the K storm we this got the L storm today
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976. JLPR2
Quoting pottery:
I'm out>>>>>>>>>


Night!
Member Since: September 4, 2007 Posts: 7 Comments: 8693
Idk if it's just me.. but Kirk has trochoidal oscillations, signs it is a very intense hurricane. wouldn't be surprised if it is 105 mph at 11pm

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Kirk sure has become an impressive storm. We are fortunate that this storm is out in the middle of the Atlantic and not a threat to land as our models did a horrible job with the intensity forecasts. NHC forecast reflects this, here was the intial forecast just two days ago


INIT 28/2100Z 23.8N 43.9W 30 KT 35 MPH
12H 29/0600Z 24.1N 45.3W 35 KT 40 MPH
24H 29/1800Z 24.3N 47.4W 35 KT 40 MPH
36H 30/0600Z 24.6N 49.6W 35 KT 40 MPH
48H 30/1800Z 25.3N 51.7W 35 KT 40 MPH
72H 31/1800Z 27.5N 55.5W 35 KT 40 MPH
96H 01/1800Z 32.5N 55.0W 35 KT 40 MPH
120H 02/1800Z 40.0N 48.0W 35 KT 40 MPH

FORECASTER BRENNAN

------

Now we have a strengthening 90MPH hurricane.
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Quoting pottery:

Ernesto and Hermine were indifferent to DMAX at first. They responded to dry air, hot air by relocating their centers South. Looks like Leslie will have to do the same facing this dry band pressing down on her, if she wants to continue.
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The L storm better start going wnw soon am looking foreword too how far W it gets overe night. It looks like its getting a little too close now
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I'm out>>>>>>>>>
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969. JLPR2
Quoting TropicalAnalystwx13:
Category 2?



Whooo! Go Kirk!
Member Since: September 4, 2007 Posts: 7 Comments: 8693



wwltvweather As of today, there has been 18.59" rain this August at Armstrong Int'l Airport. The wettest August on record. Old record 16.12" in 1977.
Member Since: June 6, 2010 Posts: 0 Comments: 4437
Plenty dry air, west of Leslie.
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Blog is dead!! Kirk lookin GOOD!!
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Category 2?

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What I think the 11pm will be
What a good looking storm, 100mph-105mph


50mph for Leslie

Member Since: March 16, 2012 Posts: 127 Comments: 7942
Jokes aside...

Leslie is already a pretty massive storm.
Not a lot feeding into it for a while, she's all on her own right now.
Impressive.
Wonder what she will look like at DMAX ?
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Estimated 151,000 New Orleans homes still without power...

http://www.nola.com/hurricane/index.ssf/2012/08/re sidents_cope_with_life_witho.html
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Quoting Grothar:
The two blobs are joining and making one big blob. It looks like Leslie is still a little elongated from North to South.


Is that convection in les CDO or randow blowup??
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Quoting rescueguy:


I know I am here in Charleston... Have not had a real ground swell this season to speak of...

If you're a Charleston surfer, then I'll bet you know my nephew.
anyway, thoughts and prayers with the folks still in harms way
goodnight.
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958. JLPR2
Quoting pottery:

OK, thanks.
Not good....


You're welcome!
Member Since: September 4, 2007 Posts: 7 Comments: 8693
Quoting avthunder:
Kirk is strengthening as Leslie curves around the protruding ridge.

Goodness me!
They'll be pumping, next. (the ridge, the RIDGE)
Everyone under the age of 60, get off the blog.
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956. beell
Quoting StormDrain:
OK. I see your thinking...


image credit: mrgo.gov

Thanks again.


With levees set back from the main line levees to "protect" the communities behind the east bank of the MR levees from storm tides from the SE and levees/dredge spoil on the west side of the MRGO.

A large funnel terminating at Braithwaite. Shell Beach and Delacroix were in the funnel as well.
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Quoting Grothar:


Sounds like a scene from one of the daytime soap operas.

(Meanwhile Kirk and Leslie are still stuck in the Atlantic)
Kirk is strengthening as Leslie curves around the protruding ridge.
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Quoting rescueguy:


I know I am here in Charleston... Have not had a real ground swell this season to speak of...

Better get your wax out.....
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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.
Levi made some comments on the winter last winter, basing his forecast almost entirely on the PDO and AO. Did a better job than Joe. And gee, maybe nobody goes out on a limb quite like Joe because the reality is that weather is very unpredictable that far out. Ever think of that?

"Ultra-long range forecasting" is not a daunting nor difficult job. It is a job that truly can not be done consistently with significant accuracy. This is not the forecasters fault, it is simply the fact that weather is very hard to predict (in the sense that it is random and chaotic) in the long range. Yet, ol' Joe will say such and such is GOING TO HAPPEN, as if the weather has no option but to follow his forecast.


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Quoting waterskiman:

Well 2 I answered you last page posted it again though


thank you, I must have missed it! :) All I kept seeing was bashing.... :)
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Really? People are talking about politics? This is a freaking weather blog. If you want to talk about politics, please take it elsewhere.
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Quoting JLPR2:


14.1n, 45.9w

OK, thanks.
Not good....
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Quoting pottery:
So, the forecast calls for Leslie to be a Hurricane, late on Friday.
The wave forecast is for 40' storm waves, north of Puerto Rico.

The surfers must be salivating all over....


I know I am here in Charleston... Have not had a real ground swell this season to speak of...
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Quoting waterskiman:

Of course he has his right to his opinion as does everyone else. I lean to the east looking north :)


hehehehehehhhhh.
I love it !
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Quoting Neapolitan:
The proof, as they say, is in the pudding:

JB's 2012 hurricane season forecast: 9-12/4-6/2-3. (The seasons's still two weeks from the peak.)

JB's spring and summer 2012 forecast: "The summer will not be as hot (more like 2009) and winter could last into April this year, centered on the [Great] Lakes."

JB's winter, 2012 forecast: "...next winter [2012], for example, will be colder than this one [2011]."

I could go on and on, but this is way too easy. Just Google any of JB's old forecasts--the ones that haven't been removed, that is--and you'll see much of the same: huge, grandstanding forecasts that go against both common sense and climatology, followed by a deafening silence when those forecasts inevitably turn out to be wrong.

I didn't know Justin Beiber was forecasting?
Know wonder those forecasts suck. LOL

Just kidding... No need to rant on about Joe Bastardi, he gets a little TOO hyper when it comes to very BIG situations... and some simple things too ;)
He likes to have "Out there" forecasts so that, one day if he's right, he'll get some big pats on his back for making the right call... When truthfully that happens 1 of 35 forecasts.
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945. JLPR2
Quoting pottery:

Hmmm... I missed that on the graph. Moving too fast.
Good spotting !

The windspeed bottomed out, the pressure too and started rising again.

Where exactly is this buoy? Coordinates?


14.1n, 45.9w
Member Since: September 4, 2007 Posts: 7 Comments: 8693
Isaac brought the Heat to Texas, 103 here today, didnt want to go from a drought to a flood anyway which is what would have happened, Best Wishes to those in La.
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Quoting Grothar:


Sounds like a scene from one of the daytime soap operas.

(Meanwhile Kirk and Leslie are still stuck in the Atlantic)

If Nadine was the one approaching Ethiopia at 4am cdt.... this will be a name to remember.
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Quoting JLPR2:


Either that is the center of Leslie or the storm is weaker than we think. 14mph this close to it? O.o

Hmmm... I missed that on the graph. Moving too fast.
Good spotting !

The windspeed bottomed out, the pressure too and started rising again.

Where exactly is this buoy? Coordinates?
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Quoting CosmicEvents:
hey, hey....US politics/actions effect the whole world. Stormpetrol has a right to an opinion. SP...I assume you're leaning west?

Of course he has his right to his opinion as does everyone else. I lean to the east looking north :)
Member Since: June 6, 2010 Posts: 0 Comments: 4437
940. JLPR2
Eye is looking better with every frame, now all it needs is some stronger convection around it.

Member Since: September 4, 2007 Posts: 7 Comments: 8693
Quoting serialteg:

South relocation is the key:



Although the GFS has been rather articulate in recognizing Southern relocs the last two months.

The minute the GFS predicts a more southerly track from fish storm, expect it to drop Leslie way South.
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Quoting muddertracker:


Kirk is a beautiful little 'cane.

I liked Gordon Better ;)

It's eye made up half of the storm by itself. xD
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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.