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Tropical Hurricane Ida

Katrina had cat 5 surge at 130mph because of its wide size. Camile which had higher winds, true cat 5, was smaller in size. However katrina surge was higher than Camile in MS.
How does forecasted Ida stack up in size, windfield expansiveness compared to Katrina verse Camile scenerio listed above?
 
ForsythSnow said:
The track did shift a hair east actually but only a hair. I overlayed the new to the old to check.
View attachment 89427
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Thanks for doing that . Its helpful to actually see the difference . Especially at this point when they will most likely be small changes and nothing drastic .


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Cadi40 said:
The ridge is always underestimated. ALWAYS. The major east shift into Alabama/Florida panhandle you guys are dying to see will likely never occur or verify. Sure there’s always a small chance and forecasting mistakes are made, but I am extremely doubtful in a major shift at this point in time. The wishcasting so blatantly obvious. I am 85% confident that this will be an LA land falling storm.
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I agree with you that a shift into Alabama/FL is extremely unlikely… I give less than a 5% chance of happening. However the ridge has been trending weaker at that time period now for a couple days and we’re inside 72 hours, so the models are getting fairly good data to be doing that. Again I think a SE Louisiana landfall is most likely at this point, I think the true effect of the weaker ridge is in how quick the models are turning it northeast once inland.
 
NCSNOW said:
Katrina had cat 5 surge at 130mph because of its wide size. Camile which had higher winds, true cat 5, was smaller in size. However katrina surge was higher than Camile in MS.
How does forecasted Ida stack up in size, windfield expansiveness compared to Katrina verse Camile scenerio listed above?
Click to expand...
From the wind maps I can pull, Katrina's wind field was massive.1630119472039.png

The GFS 850 wind map doesn't even have it nearly as large, and note the 850is much higher up so likely the wind field would remain smaller until landfall where it will expand per modeling vs shrink and dissipate more.
1630119522200.png
 
NCSNOW said:
Katrina had cat 5 surge at 130mph because of its wide size. Camile which had higher winds, true cat 5, was smaller in size. However katrina surge was higher than Camile in MS.
How does forecasted Ida stack up in size, windfield expansiveness compared to Katrina verse Camile scenerio listed above?
Click to expand...

It looks on the smaller side thankfully.....

FORECAST VALID 29/1200Z 27.8N 89.6W
MAX WIND 120 KT...GUSTS 145 KT.
64 KT... 35NE 30SE 20SW 30NW.
50 KT... 60NE 60SE 30SW 50NW.
34 KT...130NE 110SE 80SW 110NW.


Much smaller than Katrina, and smaller than Laura from last year even.....
 
Webberweather53 said:
New Orleans as a whole has also sank about 2-2.5 feet further below sea level since Katrina and the major loss of wetlands to their SE to serve as a barrier to storm surge is going to make this a very scary situation...You're probably, if not likely, fixing to watch a major humanitarian disaster unfold before your eyes.
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I think it's prudent to sound an alarm for New Orleans and for people to get out, but New Orleans is in a much better place than they were 16 years ago as far as surge protection is concerned. The surge protection system is very different than it was for Katrina. It's certainly not immune to surge, but it is much better protected. There are multiple lines of defense to stop surge, and surge is no longer allowed "inside" the city like it was before.

The city as a whole has not sunk an additional two feet. Some areas of New Orleans East and the Lower Ninth/St Bernard parish line have subsided about half that, but on a whole, the city sits on average a couple inches further down than before, and that average is skewed because of the extreme outliers. You'll see news stories mentioning rates of 2-3 inches per year, but that's for small portions of the city.

IMO, the major threat to the city these days is wind and rainfall within the levee systems. I think rain is the biggest and most likely threat. I have a very intimate knowledge of the storwater infrastructure of the city, and I have a little less than zero faith in it. The surge protection and outfall canal pumps are top of the line, but past that it gets scary quickly. An afternoon thunderstorm is enough to flood certain neighborhoods. If a train of tropical moisture sets up in the right spot, good luck. The system is theoretically able to handle 1" of rain in the first hour and a half an inch for every hour after that. At some point, due to crappy pipes and catch basins, the streets begin to act as conveyance. The city even uses 6" of stormwater storage capacity for all the streets in their calculations. It's mind-bogglingly idiotic, but whatever.

There is a possible scenario where a slow moving system keeps surge way up and dumps massive amounts of rain in the city. This would kind of fill up the areas between the lines of defense and outside the lines of defense, and once that area is filled up, it would flow back in to the city. It's a low probability scenario, but not a zero probability. A slower storm coming from a more SE angle increases the probability.

All that said, we thought the city was safe last time. It wasn't. We think the city is safe this time. We all hope it is as Ida is looking like no joke for SELA.

Source:
<-- worked on flood control for a decade in New Orleans following Katrina. I am by now means the end all be all authority, but I do have a pretty in depth knowledge of the water systems in the metro Nola area, especially the east bank portions. It has been six years since I worked in the area, so some of my information could be out-dated.
 
More guidance shifting east tonight that’s odd curious to see if the euro bites I think it will
 
At 02:46Z, a 987 SURFCE PRESSURE was located at 22.917N 83.917W. Recon found 74knot Surface Winds.

Ida (Aug. 28, 2021) - HDOB - NOAA2 - Atlantic Non-Tasked Miss. WA - Ob. 40 - Tropical Atlantic

View decoded HDOB observation 40 available for (August 28, 2021) from NOAA2 on a non-tasked mission, the first flight of a sequence of non-tasked research missions into this system, in the North Atlantic basin.
tropicalatlantic.com

There's Max winds of over 100MPH found on dropsonde at a height of 914Mbs.

Ida (Aug. 28, 2021) - Sonde - NOAA2 - Atlantic Non-Tasked Miss. WA - Ob. 21 - Tropical Atlantic

View decoded Sonde observation 21 available for (August 28, 2021) from NOAA2 on a non-tasked mission, the first flight of a sequence of non-tasked research missions into this system, in the North Atlantic basin.
tropicalatlantic.com
 
Thanks guys. Katrina eye went east NO. This will be west, way it looks now. That will be harder hit from that standpoint as it pushes water back up river. However the lake will be getting pushed away from metro , se wind until backside. Beleive the breaches where from lake, north flow on north side metro pushing down on levees Katrina. NO will get a double punch from this projected track.
 
Nash_LSU said:
I think it's prudent to sound an alarm for New Orleans and for people to get out, but New Orleans is in a much better place than they were 16 years ago as far as surge protection is concerned. The surge protection system is very different than it was for Katrina. It's certainly not immune to surge, but it is much better protected. There are multiple lines of defense to stop surge, and surge is no longer allowed "inside" the city like it was before.

The city as a whole has not sunk an additional two feet. Some areas of New Orleans East and the Lower Ninth/St Bernard parish line have subsided about half that, but on a whole, the city sits on average a couple inches further down than before, and that average is skewed because of the extreme outliers. You'll see news stories mentioning rates of 2-3 inches per year, but that's for small portions of the city.

IMO, the major threat to the city these days is wind and rainfall within the levee systems. I think rain is the biggest and most likely threat. I have a very intimate knowledge of the storwater infrastructure of the city, and I have a little less than zero faith in it. The surge protection and outfall canal pumps are top of the line, but past that it gets scary quickly. An afternoon thunderstorm is enough to flood certain neighborhoods. If a train of tropical moisture sets up in the right spot, good luck. The system is theoretically able to handle 1" of rain in the first hour and a half an inch for every hour after that. At some point, due to crappy pipes and catch basins, the streets begin to act as conveyance. The city even uses 6" of stormwater storage capacity for all the streets in their calculations. It's mind-bogglingly idiotic, but whatever.

There is a possible scenario where a slow moving system keeps surge way up and dumps massive amounts of rain in the city. This would kind of fill up the areas between the lines of defense and outside the lines of defense, and once that area is filled up, it would flow back in to the city. It's a low probability scenario, but not a zero probability. A slower storm coming from a more SE angle increases the probability.

All that said, we thought the city was safe last time. It wasn't. We think the city is safe this time. We all hope it is as Ida is looking like no joke for SELA.

Source:
QUOTE]


Sent from my iPhone using Tapatalk
Click to expand...

Could I quote this on my site with your name?
 
Nash_LSU said:
I think it's prudent to sound an alarm for New Orleans and for people to get out, but New Orleans is in a much better place than they were 16 years ago as far as surge protection is concerned. The surge protection system is very different than it was for Katrina. It's certainly not immune to surge, but it is much better protected. There are multiple lines of defense to stop surge, and surge is no longer allowed "inside" the city like it was before.

The city as a whole has not sunk an additional two feet. Some areas of New Orleans East and the Lower Ninth/St Bernard parish line have subsided about half that, but on a whole, the city sits on average a couple inches further down than before, and that average is skewed because of the extreme outliers. You'll see news stories mentioning rates of 2-3 inches per year, but that's for small portions of the city.

IMO, the major threat to the city these days is wind and rainfall within the levee systems. I think rain is the biggest and most likely threat. I have a very intimate knowledge of the storwater infrastructure of the city, and I have a little less than zero faith in it. The surge protection and outfall canal pumps are top of the line, but past that it gets scary quickly. An afternoon thunderstorm is enough to flood certain neighborhoods. If a train of tropical moisture sets up in the right spot, good luck. The system is theoretically able to handle 1" of rain in the first hour and a half an inch for every hour after that. At some point, due to crappy pipes and catch basins, the streets begin to act as conveyance. The city even uses 6" of stormwater storage capacity for all the streets in their calculations. It's mind-bogglingly idiotic, but whatever.

There is a possible scenario where a slow moving system keeps surge way up and dumps massive amounts of rain in the city. This would kind of fill up the areas between the lines of defense and outside the lines of defense, and once that area is filled up, it would flow back in to the city. It's a low probability scenario, but not a zero probability. A slower storm coming from a more SE angle increases the probability.

All that said, we thought the city was safe last time. It wasn't. We think the city is safe this time. We all hope it is as Ida is looking like no joke for SELA.

Source:
<-- worked on flood control for a decade in New Orleans following Katrina. I am by now means the end all be all authority, but I do have a pretty in depth knowledge of the water systems in the metro Nola area, especially the east bank portions. It has been six years since I worked in the area, so some of my information could be out-dated.
Click to expand...
I’m not sure I would say for definite that surge is “not allowed” inside the city. Though I do pray that you’re right. The fact is this storm appears to be coming in at an angle that is probably the worst case scenario for New Orleans. While I do think the levees will hold and not break, I’m concerned we may see water going over the top of the levees if this thing reaches strong cat. 4/5 at landfall
 
DadOfJax said:
Carolinians dying to be relevant in regards to Ida….let them talk…mute works great too!
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Honestly I don’t wish anything on the Carolinas especially the mountains. The deaths in Haywood county do to Fred is devastating really don’t need Ida


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Brent said:
Why do mets do this? The Cat 3 point is inland and not to mention there's actually a chance at a 5
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It’s not the mets fault it’s the CAT system we should allow storm surge and rain factor into being a CAT 5 not just the wind speed which often lessen upon land friction processes.
 
BirdManDoomW said:
It’s not the mets fault it’s the CAT system we should allow storm surge and rain factor into being a CAT 5 not just the wind speed which often lessen upon land friction processes.
Click to expand...

The category system based on wind is a pretty good indicator of surge, but surge variates based on geography. That is way too random a system to base hurricane designations, and rainfall is more variable than surge cause of fronts and ridges. Wind would have been fine indicator of surge in New Orleans, and the NHC could have realized this potential 36 hours ago. There was a chance this could go to Cat 5 at that point, and now it looks more likely Ida is a Category 5 than 3 at landfall (4 being most likely).
 
lexxnchloe said:
I just read up on Betsy. It was at 942mb when it made landfall. The good news is Ida is alot weaker.
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Ida will likely never be as large as the mature, Cape Verde cane that Betsy was, but it will take some good fortune if Ida isn't below 942mB at landfall.
 
Just IMO, but our mid Atlantic “thang” is becoming ever so more interesting with its influence on Ida and her track. They are far enough apart but for some reason model guidance hints at some interactions between this unknown feature @Webberweather53 C479AF51-12E2-4BA6-9537-C75812280CD2.jpeg
 
I haven’t followed closely but some are saying former Hurricane Henri is coming back from the dead in a backdoor fashion. I don’t think so, but none the less that’s interesting when both are getting closer together
 
wxdaniel said:
Could I quote this on my site with your name?
Click to expand...

Let's keep it a SouthernWX exclusive ?

Chazwin said:
I’m not sure I would say for definite that surge is “not allowed” inside the city. Though I do pray that you’re right. The fact is this storm appears to be coming in at an angle that is probably the worst case scenario for New Orleans. While I do think the levees will hold and not break, I’m concerned we may see water going over the top of the levees if this thing reaches strong cat. 4/5 at landfall
Click to expand...

Let me explain what I mean about "not allowed inside the city." Imagine the major outfall canals as well as the Industrial canal/Intracoastal as fingers of water penetrating deep into the city. Pre-Katrina, surge was allowed to freely flow from the lake and MRGO back in to these areas. The only thing protecting the city were essentially the floodwalls and levees along the outfall canals. It's totally different now. Seawalls and pump stations have been built where the outfall canals flow in to the lake. The gates are closed and pumps switched on when the surge starts coming in to the lake. On the Industrial Canal/Intracoastal/MRGO side of the city, you now have the Lake Borgne Surge Barrier as well as the closure of MRGO to stop water from coming into the Industrial Canal area.

There are still possible failures of the outfall canal walls, but that would be because of pressure from rain pumped in to the canals from the city and not from surge. That scenario would require the failure of major outfall canal pumps at the lake and their backups. It's unlikely, but as before, more than a zero probability.

We learned a lot from the Dutch. Things such as the Lake Borgne Surge Barrier were ideas drawn up during the first Dutch Dialogues. Why have many miles of defense when you can concentrate your defense in one area? It makes so much sense, and you wonder why we never did it prior to Katrina, but like the Dutch, it took a disaster to recallibrate our thinking. The Dutch didn't start their Delta Works program until the North Sea Flood of 1953. It took us experiencing Katrina to start our version of Delta Works.
 
Nash_LSU said:
Let's keep it a SouthernWX exclusive ?



Let me explain what I mean about "not allowed inside the city." Imagine the major outfall canals as well as the Industrial canal/Intracoastal as fingers of water penetrating deep into the city. Pre-Katrina, surge was allowed to freely flow from the lake and MRGO back in to these areas. The only thing protecting the city were essentially the floodwalls and levees along the outfall canals. It's totally different now. Seawalls and pump stations have been built where the outfall canals flow in to the lake. The gates are closed and pumps switched on when the surge starts coming in to the lake. On the Industrial Canal/Intracoastal/MRGO side of the city, you now have the Lake Borgne Surge Barrier as well as the closure of MRGO to stop water from coming into the Industrial Canal area.

There are still possible failures of the outfall canal walls, but that would be because of pressure from rain pumped in to the canals from the city and not from surge. That scenario would require the failure of major outfall canal pumps at the lake and their backups. It's unlikely, but as before, more than a zero probability.

We learned a lot from the Dutch. Things such as the Lake Borgne Surge Barrier were ideas drawn up during the first Dutch Dialogues. Why have many miles of defense when you can concentrate your defense in one area? It makes so much sense, and you wonder why we never did it prior to Katrina, but like the Dutch, it took a disaster to recallibrate our thinking. The Dutch didn't start their Delta Works program until the North Sea Flood of 1953. It took us experiencing Katrina to start our version of Delta Works.
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Thanks for the insight. Have you seen any estimates on the return period for a levee overtopping event. That has always been the top headline for a deadly disaster in NO. I've heard they're comfortable the new system is designed for a 100 yr storm; I was just curious what it's capable of handling.
 
Explode isn’t the right word for what will happen after the core reorganizes. This thing is gonna get ventilated like crazy while over the loop current.
 

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Nash_LSU said:
I think it's prudent to sound an alarm for New Orleans and for people to get out, but New Orleans is in a much better place than they were 16 years ago as far as surge protection is concerned. The surge protection system is very different than it was for Katrina. It's certainly not immune to surge, but it is much better protected. There are multiple lines of defense to stop surge, and surge is no longer allowed "inside" the city like it was before.

The city as a whole has not sunk an additional two feet. Some areas of New Orleans East and the Lower Ninth/St Bernard parish line have subsided about half that, but on a whole, the city sits on average a couple inches further down than before, and that average is skewed because of the extreme outliers. You'll see news stories mentioning rates of 2-3 inches per year, but that's for small portions of the city.

IMO, the major threat to the city these days is wind and rainfall within the levee systems. I think rain is the biggest and most likely threat. I have a very intimate knowledge of the storwater infrastructure of the city, and I have a little less than zero faith in it. The surge protection and outfall canal pumps are top of the line, but past that it gets scary quickly. An afternoon thunderstorm is enough to flood certain neighborhoods. If a train of tropical moisture sets up in the right spot, good luck. The system is theoretically able to handle 1" of rain in the first hour and a half an inch for every hour after that. At some point, due to crappy pipes and catch basins, the streets begin to act as conveyance. The city even uses 6" of stormwater storage capacity for all the streets in their calculations. It's mind-bogglingly idiotic, but whatever.

There is a possible scenario where a slow moving system keeps surge way up and dumps massive amounts of rain in the city. This would kind of fill up the areas between the lines of defense and outside the lines of defense, and once that area is filled up, it would flow back in to the city. It's a low probability scenario, but not a zero probability. A slower storm coming from a more SE angle increases the probability.

All that said, we thought the city was safe last time. It wasn't. We think the city is safe this time. We all hope it is as Ida is looking like no joke for SELA.

Source:
<-- worked on flood control for a decade in New Orleans following Katrina. I am by now means the end all be all authority, but I do have a pretty in depth knowledge of the water systems in the metro Nola area, especially the east bank portions. It has been six years since I worked in the area, so some of my information could be out-dated.
Click to expand...

Surge can still get inside the city unfortunately with extra stress going to be put on working levees as several of the drainage pumps are down (apparently it's a running joke for residents that a majority of them aren't working half the time (sad really)). If I was a resident there, none of this exactly instills confidence, esp when a comparable or stronger storm at landfall (remember Katrina weakened to a 3) is on the way. The lack of natural marshland to buffer the city from the Gulf of Mexico to the SE is also a major concern and arguably makes the city much more vulnerable despite the man-made barricades that have been put up. There will be much less in the way than 15 years ago to stop the water from the SE. Still a legitimate possibility this storm too passes to the east of the city and puts pressure from the north via Lake Pontchartrain
 
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