Mississippi River flood of 2011 sets all-time flow record, but has crested

By: Dr. Jeff Masters , 2:43 PM GMT on May 20, 2011

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The great Mississippi River flood of 2011 crested yesterday and today, and the volume of water being pushed toward the Gulf of Mexico is the largest ever recorded on the Mississippi, said Bob Anderson, a spokesman for the Army Corps of Engineers for the Mississippi Valley Division. "It's never been this high; it's never had this much water," he said. "There's just a tremendous amount of strain on these levees." The Mississippi crested yesterday at Vicksburg, Mississippi, reaching 57.06'. This exceeded the previous all-time record of 56.2', set during the great flood of 1927. The river crested at Natchez, Mississippi early this morning, and is now falling. The flood height at Natchez was also the greatest on record--61.91', nearly three feet higher than the previous record height of 58', set in 1937. The opening of the Morganza Spillway on Saturday helped to reduce the flood heights from Vicksburg to New Orleans by 1 - 3 feet, greatly reducing the pressure on the levees and on the critical Old River Control Structure (which, as I discussed last Friday, is America's Achilles' heel, and must be protected.) According the National Weather Service, the Mississippi River is no longer rising anywhere along its length, and the great flood of 2011 has likely seen its peak. Rainfall over the next five days will not be enough to raise the Mississippi River water levels above the crests recorded yesterday and today. While it is great news that the flood has peaked, and the Old River Control Structure and all of the mainline levees on the Mississippi River have held, the fight is not over yet. Water levels will stay high for many weeks, and these structures will take a sustained pounding that could still cause failures. If another incredible heavy rain event like we experienced in mid-April occurs in June, the levee system and Old River Control Structure will threatened. Let's hope we don't have an early season Gulf of Mexico tropical storm that makes landfall over Louisiana. The latest 2-week forecast from the GFS model is not hinting at anything like this, fortunately. It's a good thing (for the sake of the levees) that Louisiana experienced severe drought over the winter and spring--had the water levels been high throughout winter and spring, like occurred in the run-up to the great 1927 flood, the levees would have been soggy and much more vulnerable to failure once the big flood crest hit.


Figure 1. The flow of the Mississippi River past the Old River Control Structure near Simmesport, Louisiana reached its all-time highest volume on record Thursday, when the flow rate hit 2.3 million cubic feet per second (cfs). The flow of Niagara Falls at normal water levels is 100,000 cfs, so the Mississippi's flow was 23 times that of Niagara Falls. Image credit: Army Corps of Engineers.

Recommended reading
My post on the Old River Control Structure, America's Achilles' heel: the Mississippi River Old River Control Structure, is well worth reading, if you haven't done so. I plan on making a follow-up post next week discussing the economic cost of the failure of this critical flood-control structure.

Our weather historian, Christopher C. Burt, has made a very interesting post on the greatest floods to affect each continent.


Figure 2. Track forecast for Tropical Storm Four.

First typhoon of 2011 coming?
In the Northwest Pacific, Tropical Storm Four has formed, and appears poised to become the first typhoon of 2011 by early next week. The storm is expected to head west-northwest or northwest towards the Philippines. While the GFS model predicts Tropical Storm Four will miss the Philippines and recurve northwards towards Japan late next week, it is too early to be confident of this forecast.

Have a great weekend everyone, and I'll be back Monday with a new post.

Jeff Masters

In Bound (minou)
Chances of over-topping Baton Rouge or Port Allen levees are slim to none. Problems with this volume continuing for 2 weeks or longer is the question of whether the levees will stand the test of pressure. Thank goodness we've been in a drought or else the levees would be mushy inside and out! The Hwy. 190 Bridge in the distance was closed the day before this photo due to a run-away barge that struck the base.
In Bound
High Water at Baton Rouge (cmrbg06)
High Water at Baton Rouge
High Water at Baton Rouge

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Ash starting to fall in Reykjavik



Member Since: August 22, 2008 Posts: 12 Comments: 6010
956. j2008
Quoting AussieStorm:


Not liking this, 3 days over bath water, could see a high-end Cat 4 low-end Cat 5 Super Typhoon.


Click image for loop.
Can see it sucking in moisture. Expanding already.

Moisturizing the atmosphere around it.

Click image for loop

I hope people over in the philippines are preparing for this storm, a brush from a cat 5 super typhoon isnt very pretty.
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Quoting aquak9:
For all my friends in Texas:

The Texas drought will break soon
before the year does end
The rains, they are a'coming
just like an old lost friend.

Umm-hmmm. Somewhere over the rainbow, skies are grey. Somewhere over the rainbow, we'll have a rainy day.
But I'm not holding my breath!
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Quoting pottery:

Yep!


Too much shear in the central Caribbean for anything to organize right now. The diffluence that was plaguing PR has shifted to the West as the ULL retrogrades in that direction. You can see the ULL in
this water vapour loop now centered over the Yucatan channel and pulling a fetch of moisture up from the Pacific into the NW Caribbean.

Still no rain here though.
Member Since: Posts: Comments:
For all my friends in Texas:

It'll all be over
with a number or a name
Coastal Texas had mixed feelings
But most rejoiced the mention "Rain!"

It came upon a high tide
but no fullness of the moon
the winds were mostly gentle
the lands did sing and swoon

The Texas drought will break soon
before the year does end
The rains, they are a'coming
just like an old lost friend.
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Current QBO status compared to one of this season analogs.
1999(Left) 2011(Right)

Jan 1.40 | Jan 9.18

Feb 3.97 | Feb 10.05

Mar 6.79 | Mar 10.44

Apr 12.14 | Apr 10.71

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bappit- I can only tell ya, what my gut says. It's gonna come with a number or a name.
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So what is going to end the drought in southeast Texas? I figure the same events will end drought in a lot of other places, too, but that's my personal interest. I read about strong capping in the Houston forecast discussions--which seems to be the same kind of capping that contributes to tornado outbreaks further north. I don't want the tornadoes (anywhere) but when can SE Texas see either a) an end to the capping or b) some mechanisms to let convection break the cap?

North of Austin had some good rains yesterday apparently helped out by the dry line. I don't think the dry line is going to make it to Houston any time soon.
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,..trending west too


Curtains to Yellow ALERT


Member Since: July 3, 2005 Posts: 420 Comments: 127536
Quoting tropicaltank:
Interesting feature in the mid carib.

Yep!
Member Since: October 24, 2005 Posts: 0 Comments: 24022
Caribbean - Rainbow Loop



Gulf Of Mexico - Rainbow Loop
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Weird. I was looking for links on "elevated mixed layer" and clicked on one that got a malicious website warning from Norton. Maybe the site was harmless but got hacked. Just seems strange.
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View east from Reykjavík towards approaching ash.

Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting sunlinepr:


Interesting feature in the mid carib.
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lol
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting PcolaDan:
Various pictures of the Grímsvötn eruption. (a couple appear not to be and may be mislabeled)


Incredible pictures. Looks like the intensity of the eruption has lessened as well. The composition of the ash falling looks to be of a less-harmful variety, especially to livestock. Which is good news.
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You can be sure, Camping has achieved his goal; he lived a real rapture:

"As Saturday drew nearer, followers reported that donations grew, allowing Family Radio to spend millions on more than 5,000 billboards and 20 RVs plastered with the doomsday message. In 2009, the nonprofit reported in IRS filings that it received $18.3 million in donations, and had assets of more than $104 million, including $34 million in stocks or other publicly traded securities".

You can be sure that....Suddenly, all his money in his bank accounts went in Rapture, through wire transfer, in different directions; Panama, Great Cayman and Switzerland (Banks)...
Member Since: August 2, 2010 Posts: 21 Comments: 9693


Member Since: August 2, 2010 Posts: 21 Comments: 9693
Quoting beell:
12Z GFS Surface Based CAPE at/over 5,000 J/kg
Valid 7PM CDT

Kinda far from the mid-level dynamics/height falls over the upper midwest-but extreme instability along the dryline.



Several storm chasers are expecting a evening full of potential. Reed's Twitter updates have been a bit ominous today. He's looking at Eastern OK as many are.
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Dave4321, I'll second you here in the Cape (Coral) .... Not signing up for hail, but would live a good thunderboomer this afternoon. (Heck, I'm heading outside right now to start a major project; maybe that'll kickstart something! LOL)

On a serious note, I sure hope this dry pattern changes soon. My grass is getting crispy again, and my eyes are starved for falling rain.

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Various pictures of the Grímsvötn eruption. (a couple appear not to be and may be mislabeled)
Member Since: August 22, 2008 Posts: 12 Comments: 6010
935. Skyepony (Mod)
Aussie~ That's really neat MIMIC animation you posted. It shows the atmosphere coupling through all levels of Songda & becoming vertically stacked.
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Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting stillwaiting:
with a decent easterly flow and a shallow west coast seabreeze,i would expect some strong and possibly isolated severe storms along fl's west coast later this evening after 5pm


Let's Hope so. I'm a little south of you in Rotonda West, and we have been missing out over here.
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interesting little mid level feature over western cuba spinning
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with a decent easterly flow and a shallow west coast seabreeze,i would expect some strong and possibly isolated severe storms along fl's west coast later this evening after 5pm
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TS SONGDA

Hi all

This storm is developing fast and may become a threat to Luzon as a CAT 3 or CAT 4 cyclone if its not steered northward.
Gonna watch this one closely over the next few days as it develops.Has potential to be a very dangerous and powerful landfall cyclone due to its size and the perfect conditions of high SST and good outflow along its path.
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A quick animation I made of the Gulf of Mexico/Caribbean Sea Surface Temperatures on May 22nd between the years of 1998 and 2011.

May 22, 1998 - May 22, 2011 Sea Surface Temperatures
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting DEKRE:


In the US, because they don't know any better


Haha...you are so right!
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927. beell
click for full discussion
MCD 851
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Quoting beell:


PDS:
The "particularly dangerous situation" wording is used in rare situations when long-lived, strong and violent tornadoes are possible. This enhanced wording may also accompany severe thunderstorm watches for exceptionally intense and well organized convective wind storms. PDS watches are issued, when in the opinion of the forecaster, the likelihood of significant events is boosted by very volatile atmospheric conditions. Usually this decision is based on a number of atmospheric clues and parameters, so the decision to issue a PDS watch is subjective. There is no hard threshold or criteria. In high risk outlooks PDS watches are issued most often.
SPC FAQ's




ok
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925. beell
Quoting Tazmanian:
i think in oder to have a PDS you have have the EF 2 to EF5 ch up too 50% too 60% ch


PDS:
The "particularly dangerous situation" wording is used in rare situations when long-lived, strong and violent tornadoes are possible. This enhanced wording may also accompany severe thunderstorm watches for exceptionally intense and well organized convective wind storms. PDS watches are issued, when in the opinion of the forecaster, the likelihood of significant events is boosted by very volatile atmospheric conditions. Usually this decision is based on a number of atmospheric clues and parameters, so the decision to issue a PDS watch is subjective. There is no hard threshold or criteria. In high risk outlooks PDS watches are issued most often.
SPC FAQ's

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Quoting DEKRE:


In the US, because they don't know any better


Nobody knows datum is singular of data or that die is the singular of dice.

Is that big moderate zone through the northern and eastern plains for this afternoon?
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Quoting aquak9:
most important addition I see is a change to the convective scheme which seems to reduce feedback errors out past 36 hours.

CV's past 72 hours don't differ much, BUT initialization totally tightens up the models up to 72 hours dropping CV as much as 35%.

ok I have obviously had way too much coffee if some of this stuff is making sense.


When you understand it all, please post and explain it to me......
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Wind Shear.


Shear Tendency


Morphed Integrated Microwave Imagery
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most important addition I see is a change to the convective scheme which seems to reduce feedback errors out past 36 hours.

CV's past 72 hours don't differ much, BUT initialization totally tightens up the models up to 72 hours dropping CV as much as 35%.

ok I have obviously had way too much coffee if some of this stuff is making sense.
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After a short cool down last week it's back to summer:

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i think in oder to have a PDS you have have the EF 2 to EF5 ch up too 50% too 60% ch
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Quoting nrtiwlnvragn:

Thanks! That'll make your eyes blurry!
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Quoting AussieStorm:


Not liking this, 3 days over bath water, could see a high-end Cat 4 low-end Cat 5 Super Typhoon.


Click image for loop.
Can see it sucking in moisture. Expanding already.

Moisturizing the atmosphere around it.

Click image for loop


WDPN31 PGTW 221500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W WARNING NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. TROPICAL STORM (TS) 04W (SONGDA), LOCATED APPROXIMATELY 190 NM
NORTH-NORTHEAST OF PALAU, HAS TRACKED WEST-NORTHWESTWARD AT 06 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND
RECENT MICROWAVE IMAGERY (221014Z TRMM AND 221102Z SSMIS) DEPICT
TIGHTLY CURVED BANDING WRAPPING INTO A FORMATIVE EYE FEATURE WITH
DEEP CENTRAL CONVECTION BUILDING OVER THE LOW LEVEL CIRCULATION
CENTER. THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION BASED ON
THE FORMATIVE EYE FEATURE IN THE AFOREMENTIONED MICROWAVE IMAGERY.
THE CURRENT INTENSITY IS BASED ON DVORAK INTENSITY ESTIMATES FROM
KNES AND PGTW OF 55 KNOTS. UPPER LEVEL ANALYSIS INDICATES THAT THE
SYSTEM REMAINS IN AN AREA OF LOW (10-15 KNOT) VERTICAL WIND SHEAR
(VWS). DEVELOPMENT OF AN ANTICYCLONE DIRECTLY ABOVE THE SYSTEM IS
PROVIDING STRONG DIFFLUENT FLOW ALOFT. OVER THE PAST 06 HOURS,
ANIMATED WATER VAPOR IMAGERY HAS SHOWN STEADY EQUATORWARD OUTFLOW
AND IMPROVED POLEWARD OUTFLOW AHEAD OF AN APPROACHING SHORTWAVE
TROUGH.
3. FORECAST REASONING.
A. NO CHANGE IN FORECAST PHILOSOPHY.
B. TS 04W HAS TRACKED SLOWLY WEST-NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF THE MID-LEVEL SUBTROPICAL RIDGE (STR) AND
IS FORECAST TO CONTINUE TRACKING GENERALLY WEST-NORTHWESTWARD
THROUGH TAU 48. NUMERICAL MODEL GUIDANCE IS IN EXCELLENT AGREEMENT
IN THE EARLY TAUS, WITH THE EXCEPTION OF GFDN, WHICH DEPICTS A
SLIGHTLY MORE WESTWARD TRACK. TS SONGDA IS EXPECTED TO INTENSIFY
THROUGHOUT THE FORECAST PERIOD AS IT CONTINUES TO TRACK OVER
FAVORABLE SEA SURFACE TEMPERATURES AND WITHIN AN IMPROVING UPPER
LEVEL ENVIRONMENT.
C. IN THE EXTENDED TAUS, THE SYSTEM IS FORECAST TO TRACK
NORTHWESTWARD AND THEN POLEWARD AS IT ROUNDS THE SOUTHWEST PERIPHERY
OF THE STR. AN APPROACHING MID-LATITUDE TROUGH WILL WEAKEN THE
WESTERN EXTENT OF THE STR AND ALLOW THE SYSTEM TO RE-CURVE AFTER THE
FORECAST PERIOD. WITH THE EXCEPTION OF GFDN, WHICH TRACKS THE SYSTEM
INTO NORTHERN LUZON, NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT.
GFS HAS CONTINUED TO TREND SOUTHWARD BUT REMAINS THE EASTERN OUTLIER
WITHIN THE AIDS ENVELOPE. THE OFFICIAL JTWC FORECAST IS CONSISTENT
WITH THE PREVIOUS FORECAST AND REMAINS CLOSE TO MODEL CONSENSUS,
EGRR, ECMWF, AND NOGAPS.//
NNNN

Member Since: July 15, 2006 Posts: 169 Comments: 53296
916. beell
click for full convective watch
WW 322
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1st nado watch out all most up too PDS watch it has 40% ch of EF2 too EF5
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eyewall- thank you. Whoa that was some heady reading, BUT I was able to understand some performance aspects. Seems like when they tweak (poor term) a model, some of the output is improved, other output remains steady, even as far as iffy, but not much change from previous.

So much data to apply and re-apply to a single model run, one weak spot can throw the whole thing off. BUT there will always be weak spots to be found in our understanding of present-day fluid dynamics, we are only simple humans.
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Not liking this, 3 days over bath water, could see a high-end Cat 4 low-end Cat 5 Super Typhoon.


Click image for loop.
Can see it sucking in moisture. Expanding already.

Moisturizing the atmosphere around it.

Click image for loop
Member Since: Posts: Comments:
It appears that Songda has entrained some of that dry air that was lurking just north of it yesterday. However, as the upper trough finally gets by it to the north over the next 24 hours, upper outflow will improve more and allow the system to become a typhoon.

Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting Bitmap7:
Where can I access the EMXI forcast model? And when do we get access to the upgraded models?


Never heard of the EMXI model. Its probably a private model.
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0z FIMz

162 Hours (Long-Range)


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908. beell
12Z GFS Surface Based CAPE at/over 5,000 J/kg
Valid 7PM CDT

Kinda far from the mid-level dynamics/height falls over the upper midwest-but extreme instability along the dryline.

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Where can I access the EMXI forcast model? And when do we get access to the upgraded models?
Member Since: Posts: Comments:

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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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