Will New Orleans be hit by another major hurricane?

[Derek Ortt]

had Betsy have tracked about 30 miles to the east, then we would have seen the worst that would happen to New Orleans. It would have been far worse than Katrina. That said, Katrina was bad enough to last the next 10,000 years

[Extremeweatherguy]

the eye wall of Betsy missed New Orleans so it was not a Katrina that scored a direct hit with the most damgerous NE eye wall. Basically, New Orleans was in the Psacagoula/Ocean Springs zone

as was stated here many times, 100 m.p.h. sustained, ablut what New Orleans received according to the NHC report, does provide gusts approaching 140 m.p.h. and at Pass Christian, gusts may have been over 150, veyr consistent with a marginal 3

marginal cat. 3's do not usually produce gusts to 150? With Rita top gusts were only near 130-140mph (at the direct coast), and the top recorded gust with Dennis was only slightly over 120mph in the FL panhandle. All 3 of these storms were weakening storms and Cat. 3's at landfall and did not produce what I consider to be Cat. 4 type gusts. Now 150mph in a cat. 4 is completely believable, but the fact that katrina came ashore as a *weakening* 3 makes the claim of 140mph gusts (a little inland) and 150mph gusts at the coast seems somewhat unbelievable.

http://www.srh.noaa.gov/lix/html/psh_katrina.htm
^^gusts to the magnitude you describe can be found nowhere (from any site) in the post storm report. The highest gust I can find is 135mph and that's at the Pearl River Count, MS EOC. The top gust I can find for New Orleans is 98mph. Also, looking at the radar loop below...it looks like N.O. missed the NE eyewall with Katrina, and was in the NW eyewall which is much weaker.

http://lwf.ncdc.noaa.gov/img/climate/re ... dar-la.gif

[MiamiensisWx]

Yep... in my opinion, the reports on Katrina and Wilma by the NHC have not been very good.

[Derek Ortt]

extreme weather,

have you even read what asklahuna has posted many times on here? He has documented and cited scientific studies that over land the peak gust to sustained ratio is 1.4 to 1.6. Therefore, a gust to 150 is very consistent with a marginal 3

cat 1 sustained brings gusts to about 130. Vero Beach during Jeanne before the ob failed had a sustained wind of 76KT with a gust to 111

Also, there were no obs from the direct hit area of Rita (I question if Rita even was a 3 at landfall, but I'll save that argument for another thread)

[Audrey2Katrina]

Ummm, the NHC Katrina Report cites a land measurement of sustained 84 KT. winds at the Michoud Facility in New Orleans. By my understanding that translates to a fairly solid 95 plus mph steady. It is conspicuously absent in the link which concedes that a lot of the data is incomplete and could hardly be described as accurate guages of windspeeds since virtually all of the instruments failed well before closest approach. I doubt you would find any sane individual who would believe that the top windspeeds in Slidell were in the 30-40 kt range--this report substantiates nothing beyond its own incompleteness.

A2K

[Audrey2Katrina]

That said, Katrina was bad enough to last the next 10,000 years

On that we can agree quite completely. As to the previous, it's an interesting (in a horrific way) speculation, and one I would never wish to see occur; that said, I believe my point about Katrina taking "Betsy's path" has been fairly well substantiated.

A2K

[Audrey2Katrina]

On a slightly different note, it would appear that "technically" Katrina made THREE landfalls, one just south of Buras, and crossing the Mississippi river delta region thereabouts, afterwhich she most certainly entered Breton Sound. From there she could not possibly have reached the extreme SE portion of St. Tammany Parish near the La. Miss border where they report "second landfall" without first crossing the stretch of mostly marshland some 10-15 miles wide (wider than the Buras crossing) on the eastern parts of St. Bernard Parish. I concede that this "land" is largely marsh; but it is decidedly not "over open water". Any map of the area will clearly show this. In order to classify as a "landfall" does it necessarily have to be in or near a populated area above sea level, or would a "landfall" over marsh be a conceivable reality? I ask this in all sincerity, as it passed over MORE water coming from Buras across Breton Sound to St. Bernard Parish, than it did in crossing from St. Bernard to what it did of Lake Borgne before hitting the mouth of the Pearl.

A2K

[Extremeweatherguy]

extreme weather,

have you even read what asklahuna has posted many times on here? He has documented and cited scientific studies that over land the peak gust to sustained ratio is 1.4 to 1.6. Therefore, a gust to 150 is very consistent with a marginal 3

cat 1 sustained brings gusts to about 130. Vero Beach during Jeanne before the ob failed had a sustained wind of 76KT with a gust to 111

Also, there were no obs from the direct hit area of Rita (I question if Rita even was a 3 at landfall, but I'll save that argument for another thread)

I have always heard that you add the movement of the storm to the sustained wind to find the top winds in the eastern eyewall and you subtract that number in the western eyewall. Since N.O. was in the western eyewall...that would calculate out to about 105-115mph for them and to the east may be 135-145mph gusts...and with a DYING storm, gusts can even be lower...we have seen it many of times. Once again...Dennis was a 120mph Cat. 3 at landfall...but the highest gust was only about 121mph.

Also...on a different note...I found a big mistake in a report by the mobile-pensacola NWS. It says that only 3 storms had made landfall with higher sustained winds than Katrina in the U.S. (this was before being downgraded to a 3) and they named Andrew, Camille and the Labor day storm...but did they forget about 150mph Charley or any of the other many Cat. 4 storms that have hit in the past. I mean what about the 1900 storm, the TX Indianola storm, the 1919 Florida Keys storm, the Ockechobee storm, Dona, Carla, etc, etc? They made it seem like Katrina's landfalling winds were the 4th strongest EVER in the US at landfall..which we now know is very false. Just found that interesting, and yes it is off topic completely, but it is still interesting. Here is the site that makes this claim:

http://www.srh.noaa.gov/mob/0805Katrina/

[Derek Ortt]

the Dennis gust was also outside of the RMW by 5 miles

I have no clue what the report was saying that Katrina had the 3rd highest wind speed ever at 120KT. Hugo may be increased to a 5 at Charleston on reanalysis was the 141KT flight level winds were between 650 and 600mb where a near 100% reduction is needed, Camielle, nobody knows for sure after Katrina. Donna was 120KT at the Keys and revised down to 100KT at Naples. In short, that report saying that Katrina had the 4th highest winds ever was bunk

[Pearl River]

This was before the Official Final Report on Katrina:

There have been only 3 storms with stronger sustained winds when they made landfall in the U.S.:

· The Labor Day Hurricane, Florida Keys, September 2, 1935, Category 5, 892 mb
· Hurricane Camille, Mississippi, August 17, 1969, Category 5, 909 mb
· Hurricane Andrew, Southeast Florida, August 24, 1992, Category 5, 922 mb


Katrina did have the 3rd lowest landfalling pressure though at 920 mb.

[Extremeweatherguy]

This was before the Official Final Report on Katrina:

There have been only 3 storms with stronger sustained winds when they made landfall in the U.S.:

· The Labor Day Hurricane, Florida Keys, September 2, 1935, Category 5, 892 mb
· Hurricane Camille, Mississippi, August 17, 1969, Category 5, 909 mb
· Hurricane Andrew, Southeast Florida, August 24, 1992, Category 5, 922 mb


Katrina did have the 3rd lowest landfalling pressure though at 920 mb.

yeah that is true, but not the 4th highest winds.

[Audrey2Katrina]

In actuality, nobody really knows what the highest winds are in any major hurricane with complete certainty; as unlike pressure which can be measured from relative safety, surface winds are scattered all over the place and vary widely. There is just no way to certify where or what the max windspeeds in a particular storm were/are/could have been; which is why they pretty much always stipulate (unless citing a specific anemometer or other device at a particular location) that windspeeds are "estimates".

A2K

[JonathanBelles]

that a stetement i can certify

[zoeyann]

Derek and Audrey2Katrina, I understand the points you are trying to make. I respect you both especially Derek as a pro and you both seem to have a meterological understandig of the storms I can only hope to acheive. But like someone said in an earlier post there was substantial flooding for Besty, but Derek refuted with Katrina put much more of the city underwater. My opinion, which I'll concede could be far from correct, is the imense land loss that has occured in the subsequent 41 years since Betsy. I'll put up some links so you can give me your input.

On the center of the page is a time lapse of land loss of the ponchatrain basin.

http://www.lacoast.gov/geography/po/index.asp

Here is a general map
http://www.nwrc.usgs.gov/upload/landloss11X17.pdf

These are our decaying toe

http://www.nwrc.usgs.gov/upload/landloss11X17.pdf

The Houma courier also run a story that parts of Terrebonne parish have sunk up 7 inches in the last decade. I am sure New Orleans is going at a similar rate, but I do not know how much.


Anyway it is just my opinion, but I believe this made a big difference

[wxmann_91]

Derek and Audrey2Katrina, I understand the points you are trying to make. I respect you both especially Derek as a pro and you both seem to have a meterological understandig of the storms I can only hope to acheive. But like someone said in an earlier post there was substantial flooding for Besty, but Derek refuted with Katrina put much more of the city underwater. My opinion, which I'll concede could be far from correct, is the imense land loss that has occured in the subsequent 41 years since Betsy. I'll put up some links so you can give me your input.

On the center of the page is a time lapse of land loss of the ponchatrain basin.

http://www.lacoast.gov/geography/po/index.asp

Here is a general map
http://www.nwrc.usgs.gov/upload/landloss11X17.pdf

These are our decaying toe

http://www.nwrc.usgs.gov/upload/landloss11X17.pdf

The Houma courier also run a story that parts of Terrebonne parish have sunk up 7 inches in the last decade. I am sure New Orleans is going at a similar rate, but I do not know how much.


Anyway it is just my opinion, but I believe this made a big difference

Yes, the land has sunk a lot, so if Katrina hit 40 years ago, New Orleans probably would not have flooded as much as it did last year, if the levees were as high as they are today. The levees were not as high though 40 years ago, and they were not enlarged until after Betsy.

[JonathanBelles]

and they're still not high enough, should be at least 30 ft

[wxmann_91]

and they're still not high enough, should be at least 30 ft

Problem with levees is that the more high you build them, the less natural flooding, and the more pressure you exert on the earth below. Both these leads to a faster rate of sinking, which then requires even higher levees, even more sinking, etc. The only solution to this problem is to increase wetlands and decrease the amount of urbanism, or otherwise much of southern Louisiana is underwater in 100 years, even if there are 100 ft levees.

[JonathanBelles]

true y did they build that city in the 1st place (no offense)?

[Audrey2Katrina]

There is absolutely no disputing that the Louisiana coastline (particularly marshlands) have been vanishing, at the rate of a football field a minute. The worst areas of land loss are in the region from the mouth of the Mississippi across Breton Sound, and through the Lake Borgne Basin... interestingly enough THIS IS the track Katrina took. And it COULD well be a reason that even though Katrina was weakening-- the level of weakening from 1st landfall to 2nd (or 3rd, depending on how you wish to look at it), was minimal.

On the other hand, had it taken a Betsy course, the land differential is far less using the USGS map showing land loss from 1930 to 2000. Bear in mind much of that "red" was already gone in 1965 when Betsy hit, and what little more in THAT area that had disappeared would have made not much of a difference. Even the Lacoast.gov site acknowledges the VAST majority of marshland loss is in the Pontchartrain, Borgne, and Maurepas basins--none of which would have had much of any impact on slowing or weakening the Betsy path even now. The very fact that Betsy STILL managed to bring winds up to 125 mph in New Orleans travelling over much more physical terrain than did Katrina as it moved inland is the reason I suggest that Betsy, "by the record" seems to have been a stronger storm--and yet, the numbers, certainly by pressure intensity, suggest otherwise. As far as how much flooding New Orleans received from Betsy... look at a map, and draw a line from Elysian Fields Avenue, up to Gentilly, over to the Orleans St. Bernard line and you'll find a pretty big area that flooded--and yet I concur it was not remotely as extensive as Katrina's which passed to the EAST of the city, and was allegedly a slightly weaker storm.

What I consider a major reason is the Mr.Go bit of stupidity which is a MAJOR contributor to the loss of marshland in the Borgne Basin. This UNNECESSARY and destructful waterway NEEDS TO GO! The "funnel" effect of water surging up this man-mad disaster waiting to happen, along with the Gulf Outlet and Lake Pontchartrain ALL contributed to massive water surges against those levees in the area. Had this monstrosity not been there, it is QUITE possible that the 17th St. Canal, and probably London Ave as well, would still have breached; but the Industrial Canal taking the surge from MRGO might not have. Speculation, of course; and hindsight is 20-20; but most physical geographers perusing the data agree that the MRGO was a major contributor to this disaster.

Okay, that was a lot, Zoey; but in essence what it states is that I agree that loss of marshlands in La. have created a much "smoother" track for hurricanes, especially those taking a slightly "EAST" tack of the city. Those coming from the west will encounter much more land, and hence, weakening, and had Katrina taken a Betsy path it is quite likely the damage wouldn't even remotely be what we've seen--IF she were as "weak" as is being reported (an assessment I still have serious issues with but let's not re-open that can of worms). As far as your concern for the Houma, Thibodeaux, area--I can certainly understand your reasoning. I would have wished this scenario on NOBODY. If you check that USGS map carefully, you might find it interesting to note that the Atchafalaya basin is one of the FEW areas where land "gain" is taking place--and it's precisely because the Mississippi is trying very much to move back down in that direction--including with increased deposition.

The truly "worst" scenario for New Orleans, as I see it would be for a Betsy type storm (or God forbid-worse) come barrelling UP the Mississippi River bringing that enormous surge with it, and still bringing sizeable surge and wind blowing Lake Pontchartrain over the top from the North. NOT a nice scenario--and it was the RIVER surge that caused breach of Industrial/Florida canal as Betsy was headed much moreso that way before it, thankfully (for New Orleans) veered a tad more to the west.

Close the MRGO completely, and let's reclaim the Borgne Basin!

Sorry about the long post; but this is something I've been involved in researching for some time with professors at UNO in my graduate studies many moons.

A2K

[Pearl River]

fact789 wrote

true y did they build that city in the 1st place (no offense)?

The French had soon realized that their forts along the Gulf Coast were unable to assure control of the Mississippi. A garrison town near the mouth of the river with a shorter backdoor route to the Gulf that could be protected by forts would assure control of the river and the lower Mississippi Valley. In 1718 Jean Baptiste La Moyne, Sieur de Bienville, established New Orleans as the capital of Louisiana and a fortress to control the wealth of the North American interior.


The French did it.