1992 Andrew report update

[m_ru]

Pascagoula recieved wind gusts to 120 mph during Katrina and wind gusts around 80 mph during Ivan.

[Aslkahuna]

That would imply 85 mph sustained winds or less which is Cat 1 for Katrina and not even sustained hurricane force for Ivan.

Steve

[Margie]

That would imply 85 mph sustained winds or less which is Cat 1 for Katrina and not even sustained hurricane force for Ivan.

Steve

That's about right. The highest gust from the Pascagoula EOC was 108kts or 124mph from around 7:30am I believe. There were higher gusts that were not recorded...the roof of the EOC came off some time around 8 or 9am. Winds were high there throughout the morning. The EOC is...was...practically on the water, just a couple of short blocks inland off the mouth of the Pascagoula River, which is a wide estuary...not much to impede the hurricane winds coming onshore. Inland at Trent Lott airport no high gusts of that nature were received. Trent Lott airport is like 8 or 9 miles inland, north of Pascagoula and Moss Point, and NE of Escatawpa.

There was an unofficial gust reported in the newspaper of 136 mph before roof failure. Once they started getting gusts like 135mph and higher the roof was not designed for that. The location was also unfortunate with not very much to block onshore winds; Pearlington County EOC also had the the roof come off due to high wind gusts. Inland MS just east of the eye received a lot of high wind. And Hancock County EOC had the same problem but with waves, not wind...waves broke down the wall of the courthouse and they all thought they were going to buy the farm.

With Ivan, my brother called me around 1 or 2am when Ivan was peaking in Pascagoula; he always calls me if he can to let me know he's gotten to a safe spot...in this case he was already off duty. They weren't getting sustained hf winds, and the fact that he was able to get off duty speaks for itself, but they did get some impressive gusts that did not quite make it down to the ground level. He told me all the tall thin pines were bending way over in concert, that it was something to see. They had gusts coming through every 3 to 5 minutes at that point.

They did get a period of sustained winds above 50mph or so, because after a certain point they let all the deputies out on patrol know that it isn't safe to be out on the road anymore, and they come in. But they were on the back side and didn't get much from Ivan. Georges, a different story, sustained winds blew for some hours as they were just to the right of the eye, but it wasn't an extremely strong storm. They got a lot of rain with Georges though, a lot of rain.

[wxman57]

Pascagoula is 65 miles from where the center of Katrina moved ashore. My mother lives there (Gautier, just west of Pascagoula). I've been there a lot in the past few months rebuilding my mother's home. I didn't see much evidence of any more than minimal hurricane-force winds that far east of the center. The HRD post-storm wind analysis puts Pascagoula on the edge of the 75 mph sustained wind field. Looks quite good to me:

http://www.aoml.noaa.gov/hrd/Storm_page ... ll_mph.pdf

Oh, and with Ivan, they didn't get hardly anything. Just a few small tree branches down. Ivan's western side collapsed prior to landfall.

[wxman57]

Margie, have you been down here to the coast to look at the surge damage? If not then you need to before you make comments concerning the surge. So in your opinion what would a Cat-5 surge be on the coast, 50 feet? Katrina's surge was the greatest since the French settled the Mississippi coast and I'm sure we've had our share of big hurricanes since 1699......MGC

Why do you have to see it to comment on it. Please correct me if I am wrong but storm surge values are not static numbers. For one coastline Cat 3 surge may be 12-15 feet while on another one 18-22 feet may be representative of a Cat 3 surge. So if the measured surge in MS fell within established Cat 3 levels for that section of coastline then that is how it should be classified ....whether one sees it or not.

docjoe

Sure they vary from from one point to another but I do believe the surge was even more than the NHC expected.Even by there own remarks Katrina was a once in alifetime at best and was a freak system.Surge going in 5-6 miles is not normal with any system we have seen in these parts ever.This being said would not if it was considered a NORM then the new elevations for construction reflect this,they don't.They are on the order of what we usually observe it's varing at the moment form 4'-8' depending on municapality.
Saffir scale list surge normally for a Cat 5 will exceed 18' (30'+ in some areas)and flooding between 5-10 miles inland.A Cat 4 results in damage to lower floors near the shore with major damage per the NHC.I think total destruction nothing left hardly of 90% of the structers all along the coast does not even fit the Cat 4 rating by the NHC.Houses that have existed for up to 175 yrs old are gone people nothing is left on the beach it looks like Hiroshima if you need a picture.I just went back and read the 6:00 am advisory 18'to 22' surge expected as much as 28' locally these all happened and exceeded in some cases these are in line for a Cat 5 surge per the NHC.

Once again, relating a Saffir-Simpson wind rating to a particular height storm surge is meaningless. By definition, a storm surge originating from Saffir-Simpson Category 3 hurricane (based 100% on max 1-min surface wind) can only be a "Cat 3 storm surge". The problem is that the SS scale is ONLY a wind scale. After its inception, there was an attempt to correlate a SS scale number to a particular storm surge. But doing so is extremely difficult, as storm surge depends on so much more than the peak wind in what could be a very small part of a hurricane.

Storm surge is a function of the entire areal coverage of the hurricane's wind field - something Saffir-Simpson completely ignores. It's also a function of the hurricane's forward speed and the angle of incidence at landfall. Coastal topography (and the sea floor just offshore) play a tremendous role in storm surge generation.

I have a copy of hte U.S. Army Coastal Engineering Research Center's "Shore Protection Manual" right next to me. SLOSH was worthless for predicting Katrina's potential surge, because it assumed that Katrina was an average-sized hurricane. But using the shore protection manual, we calculated the internal/external pressure difference, angle of incidence into the coast, found the coastal surge multiplier for SW MS (1.9, by the way), and came up with a prediciton of about 30 feet for peak storm surge near landfall. That was a lot closer than using SLOSH for a Cat 3.

It's all about the SIZE of the wind field, not the peak wind speed. Katrina's huge 75+ mph wind field generated waves of 50-80 feet. These waves moved into the coast prior to the arrival of the center, creating what is called a "setup tide" of 6-8 feet in some areas. When the hurricane moved ashore, the storm surge moved in on top of this setup tide, creating the huge surge. In contrast, Camille did not produce such a setup tide. In fact, offshore winds prior to Camille's arrival led to tides 3-5 feet BELOW normal before Camille roared ashore back in 1969.

Finally, had Katrina maintained its peak core winds of 150-170 mph at landfall, there would have been A LOT more wind damage than was observed, but the surge probably would not have geen too significantly different, because the whole areal coverage of the 75+ mph winds would not have been any different.

For what it's worth, I have driven down the MS coast recently, taking lots of pictures. The damage I saw was incredible, but I completely believe that Katrina was no more than a Cat 3 on the SS scale at landfall. There was just no evidence of tremendous wind damage that could be attributed to 115+ mph winds, just surge damage. Most inland areas probably saw less than 100 mph sustained winds with Katrina.

[Margie]

You make some good points but consider this. While the one SLOSH run for Katrina may have been on the low side, the HES (Hurricane Evacuation Study) storm surge maps, which are graded for Cat 1-5 (an association has been made between the SS scale and the probable surge, because public warnings are based on the SS scale), were *extremely* close, all across the coast. Those maps are based on the worst-case flooding from many SLOSH runs of many different hurricane scenarios, and are detailed down to individual street addresses. And except for a very limited coastline area to the right of the eye, the surge for the most part followed the HES Cat 3 predicted floodline all the way across the MS Gulf Coast, to just east of Pascagoula. The breadth of the Cat 3 surge corresponds to Katrina's large size.

I can tell you about detailed areas where the surge matched exactly the particular areas corresponding to Cat 3 surge on the map.

If I was on the MS coast this summer and a strong hurricane was coming, I'd trust those detailed HES maps.

Also, warnings were fairly accurate, although I wish LIX had focused more detail on the MS Gulf Coast. My brother said the Jackson County Sheriff's dept was told to expect 15-20 ft of surge. Guess what...in the western part of the county, Ocean Springs got about 21 ft on average, and the surge in Pascagoula ranged from 16-18 feet (higher the closer to the coast and to the river), tapering off to about 15 feet just east of the city towards the bayous and protected wetlands.

[Pearl River]

I think we should all stop arguing whether Katrina was a cat 3, 4 or 5 or what the category was for storm surge.

I Know one thing, my dad's house in south Slidell is 4 miles from Lake Pontchartrain and about 1.5 miles from Palm Lake. His elevation is abt 6ft asl and he had abt 6ft of still water around his house, so we are talking abt a 12ft storm surge at his location. His neighbors house across the street is now a vacant lot. They stayed during the storm and were in a boat taking pictures. I have a picture of the water at that location. I have never seen anything like it in my life.

We are never going to truely know the full extent of the power of Katrina because science is not exact. We never had the SS scale prior to 1970 and what Katrina and others have shown, this is not working either.

People stay for one reason and it's not because they are fool hardy. It's because they have worked all their lives for what they have and want to protect their property from the hoodlums we have grown accustomed to seeing on the news. It's not just New Orleans as the media wants everyone to believe, it's everywhere.

I have one big gripe about this whole thing and it actually just down right p**@es me off. I don't like someone who is sitting behind a computer, several hundred miles away, looking at maps and pictures and telling me what kind of destruction we have had, in their opinion, whether it's coastal or inland. I have been in New Orleans, I have been on the coast, and I see it in Slidell everyday. There are a lot of areas off of the main Interstate that have received tremendous wind damage. It's devestation, a lot of people still don't have places to live and have yet to receive those beautiful FEMA trailers. I have 10 people living in my house right now. It's not fun.

If I sound ugly, I apologize. It has to been seen in person and don't tell me that seeing it in person makes no difference. YES IT DOES.

[Pearl River]

Margie wrote

Also, warnings were fairly accurate, although I wish LIX had focused more detail on the MS Gulf Coast. My brother said the Jackson County Sheriff's dept was told to expect 15-20 ft of surge. Guess what...in the western part of the county, Ocean Springs got about 21 ft on average, and the surge in Pascagoula ranged from 16-18 feet (higher the closer to the coast and to the river), tapering off to about 15 feet just east of the city towards the bayous and protected wetlands.

Slidell recieved their information from the Hurricane Center and SLOSH models and they did focus alot on the coast. It was broken down by CWA.

[vbhoutex]

The one thing I want to keep telling everyone is that just because the instruments say it didn't happen doesn't mean it didn't happen. All of the pro mets on here will tell you that hurrricane winds are very capricious and what happens on one block may not happen on the block next to it. We have no way of "proving" what Category Katrina was, but when we look at the damage that isnot on the main drags and compare it to the scales available to us then we can get a real sense of what did happen. I do understand that the professionals "have" to go with what was recorded, but that doesn't make it so just because "that is what was recorded". this all gets back to how do you measure the destructiveness, the winds, etc. of a hurricane. There really is no set of perfect way so IMO we need a blend between the "Actual recorded(sketchy at best) and "actual observed"(obviously subjective)by trained observers.

[MGC]

Thats right, as long as winds are the only destruction parameter the SS scale uses, this type of tragedy will continue. The SS scale should be updated to include water, as water is the predominate threat for loss of life in a hurricane. Andrew and Charley didn't kill as many people yet these two hurricanes, based solely on the SS scale are worst to ride out. Face it, the SS scale is flawed and a new system of rating hurricane intensity should be developed......MGC

[Margie]

The SS scale should be updated to include waterMGC

It already is on the HES studies. The maps have storm surge broken out by areas representing Cat 1 through Cat 5.

[Javlin]

I agree WX57 the winds in my neck of the woods in W Biloxi was probably on order about cat3(low end) around my place.Too be quite honest Georges scared me more than either Elena or Katrina wind wise.I do not know if it was the fear of the dark and all and all the howling that occured that night.I just remember that when they said we where in the eye that night I finally relaxed for I knew it was going to stall.The Goula area got pounded for my sleep that night.The tourist industry the next summer never missed a beat after those to storms.Unlike now it will be many years before we see it at full swing again.Like after Camille for many years steps to nowhere remained abundant.