National Climate Data Center Katrina Report

[Pearl River]

Normandy. You said you don't need to see the damage first hand, that you saw Katrina's? Well did you see damage first hand or not? If not, you have no idea what the heck you are talking about.

Derek. Where is this surge scale for the MS coast? Where is the official report that wind gust were 190 mph in Camille?

Margie. Where do you live? Is it on the MS coast?

Katrina Storm surge in Slidell was 8 feet. Slidell is 10-12 feet above sea level. That makes the storm surge 18 to 20 feet asl.

[/quote]

[Derek Ortt]

ftp://ftp.nhc.noaa.gov/pub/storm_archiv ... elim06.gif


the way they determined the landfall intensity is in retrospect, amateurish

[Lindaloo]

Once again... Katrina had Cat 3 winds with a Cat 5 surge. Ultimately, winds determines what it goes in the book as. I've seen the pictures on the TV and internet... and all of the catastrophic damage I see(and there is a lot, I'm not downplaying it) is from WATER. I see very little evidence of significant structural damage from wind.

It may have been a Cat 4 in LA... but it was a 3 in MS.

I agree with the CAT5 surge, but with structure damage I am going with a CAT4.

If you think there is no damage from wind then you need to take a ride down here. You will be humbled.

[Lindaloo]

ftp://ftp.nhc.noaa.gov/pub/storm_archives/atlantic/prelimat/atl1969/camille/prelim06.gif


the way they determined the landfall intensity is in retrospect, amateurish

Please clarify that statement Derek. I highly doubt anyone at the hurricane center is an amateur.

[f5]

http://www.sunherald.com/mld/sunherald/13128405.htm

Posted on Thu, Nov. 10, 2005
FEMA MAPS ARE COMINGSatellite technology is showing new advisory flood elevations, lot by lot. It will also show Katrina's surge.By ANITA LEEGULFPORT - Beginning Nov. 18, South Mississippians can go to the Internet and pinpoint flood elevations recommended for construction on coastal property.
FEMA is using satellite technology to generate maps showing new advisory flood elevations, lot by lot. Maps also will show Katrina's tidal surge, which was even higher.
"Quite frankly, in terms of hurricane storm surge, nothing compares to Hurricane Katrina. Not even close," Todd Davison, FEMA's mitigation director for this region, told the Sun Herald on Wednesday. He said the surge from Hurricane Camille in 1969 was 10 feet or more lower.
Katrina's highest recorded surge was "35 feet," on the Mississippi Sound in west Pass Christian.While new advisory flood elevations are lower than Katrina's surge, they are 3 to 8 feet higher than current flood elevations in the three Coast counties.
FEMA is urging Coast cities and counties to require that residents build to the new advisory elevations, designed to minimize loss of life and property.
Governments that fail to adopt the elevations could jeopardize millions in federal dollars, including grants to homeowners for elevating their houses and funding to reconstruct public buildings at safer heights.
"These advisory maps are trying to advance what is the inevitable," Davison said.
Homeowners who build to the higher elevations could see discounted insurance rates.
In 18 months, FEMA expects to finish tweaking new flood elevations, bring them back to local governments for public review, then publish final insurance rate maps.
Local governments must then adopt the new maps or be dropped from the National Flood Insurance Program, started in 1968. Residents who rebuild at current elevations will pay rates from those maps.
The 1982 maps currently in use were developed using old data and technology. Davison said the budget to update maps was very limited until 2003, when Congress increased it six- to seven-fold as the intensity and frequency of coastal storms emphasized the need for better information.
FEMA was working on new Coast maps when Katrina hit. The agency produced them as quickly as possible so rebuilding could begin in South Mississippi. Developing the advisory elevations created debate within the agency, he said.
"No. 1 is timing," Davison said, "We have never tried to do anything this fast before and hold the science together."
The elevations show how high above mean sea level a building should be raised to minimize flood risk. There is a 1 percent chance in any given year that water will reach flood elevations.
"It's all about the elevation," Davison said. "The higher you go, the safer it is."
FEMA flood maps will be available at http://www.fema.gov after Nov. 18
Todd Davison, FEMA's mitigation director

--------------------------------------------------------------------------------

Redrawing the maps
While Hurricane Katrina is on everyone's mind, FEMA officials say they are not raising their flood elevation guidelines to protect structures based on Katrina's water. That might be impossible, given the size and severity of Katrina. Below are some highlights of the process the agency is using to redraw flood maps.
• Flood zones are based on "100-year" flood levels. An area's recommended building height is based on a 1 percent chance in any given year that floodwaters would reach or exceed that elevation. Katrina's flooding weighs in on this data, but it's combined with storm data dating back to the turn of the century.
• FEMA is using satellite mapping technology, far more sophisticated and accurate than technology available when Mississippi's coastal floodplain maps were last overhauled in 1982.
• Engineers had to move quickly to map Katrina's storm surge because much of the data was "perishable." They marked water and debris lines. There were some problems finding "benchmarks," FEMA officials said, because many benchmark areas had been blown away or destroyed.
• Flood mapping is expensive. FEMA officials said it can cost $500,000 to $1.5 million per county.

[wxmann_91]

Not trying to respark the debate on Camille's intensity, but the link Derek provided with Camille's TC report is interesting to say the least.

...the Weather Bureau Office at New Orleans recorded only one inch.

I have to admit that sounds fishy. Either the reading was wrong or either that must've been some serious dry air entrainment into the western side of Camille right before landfall.

[Lindaloo]

Pascagoula is not a mile deep. I do not know where that comes from. I am 2 miles from the beach in Pascagoula and I had water in my home.

The EOC is not the only structure in Pascagoula that had roof failure.

OK...it is almost two miles inland up to about Hwy 90. One mile, two miles, I remember I could ride my bicycle around the entire town and still not get enough exercise.

The point I was making was that most of the city is so close to the water that it could experience strong winds coming onshore. Locations further inland such as Trent Lott airport did not experience winds that were nearly as strong.

This point has nothing to do with flooding. As a matter of fact Jackson County had flooding right up to the George County border.

Have you been to the airport? My friends live up that way, saw no flooding, but they lost their roof. That area had alot of damage and it was not from flooding.

Second, you can't possibly know Pascagoula if you say now that Pascagoula is 2 miles deep. lol. It is approximately 5 miles from the beach to HWY 90. You are giving everyone here the impression Pascagoula is some little town. You either do not know this area or you have not been here since the 70's.

[Margie]

those SLOSH models are out of date as Katrina proved the NHC forecasted a 15-20 ft storm surge on the MS coastline boy were they wrong

Those SLOSH runs that generated the maps for the MS Evac Zone Tool were very accurate. They were done I believe around 2000, 2001 timeframe. Let me give you just one example of their detailed accuracy. The Sheriff's sub station where my brother coordinated rescues in western Jackson County is situated on a tiny island of land off Washington Ave that only floods Cat 4 or above. When Kat's surge peaked, the sub station was surrounded by water, including water in the parking lot behind the station, and across the street. Water came up to the doorjamb but didn't come in, and there was a foot of water in the parking lot (which didn't hurt the squad cars; however all the windows were blown out of all of them so they got pretty wet on the inside anyway). That can be seen on the map. The flood levels are designed to go to down to the individual address level; you can type in your street address and find out what level of hurricane will flood your home (worst case scenario).

NHC did not forecast 15-20 ft surge.

COASTAL STORM SURGE FLOODING OF 18 TO 22 FEET ABOVE NORMAL TIDE LEVELS...LOCALLY AS HIGH AS 28 FEET ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE CENTER MAKES LANDFALL.

That proved to be correct. At the far eastern end of the MS coast, Pascagoula received 16-18 feet or surge. Surge was around 25 feet or a little higher locally where the eye made landfall. Along the shore, waves on top of the surge did additional damage (such as washing the dolphins out of their 30-ft high tank and into the GOM...where they were later all rescued). Waves on top of the surge broke down one wall of the Hancock Cty EOC, unfortunately located in the courthouse, very close to the bay, leading everyone inside to believe they were going to be drowned in the storm.

Regarding Pearl River's last post...go to mapquest.com, where they conveniently have a scale associated with each level you zoom in. Set the zoom level to "city." It is two miles inland from Beach Blvd to Hwy 90. Five miles inland, you'd be leaving Moss Point for Escatawpa. Trent Lott airport is about 7-8 miles inland, NE of Escatawpa. The EOC, in Pascagoula, was located about 400 yds from the Pascagoula River. There isn't much to protect it from huricane winds coming right in off the estuary. That is why winds at the EOC were clocked much, much higher than the max one-minute winds at the airport (the max sust wind at the airport was 64kt...just barely Cat 1).

[f5]

COASTAL STORM SURGE FLOODING OF 15 TO 20 FEET ABOVE NORMAL TIDE
LEVELS...

this was the mississippi landfall they drop the ball the 28 ft is when Katrina was a CAT 5 monster

[Pearl River]

Pascagoula is located in Jackson Co. This area is approx 60 miles from where the center actually came ashore at the Mouth of the Pearl River, not Gulfport or Biloxi which everyone wants to claim. Thats why the storm surge was not as high there.

[Air Force Met]

Please clarify that statement Derek. I highly doubt anyone at the hurricane center is an amateur.

He's said in retrospect. Looking back at it now...yes. It's kinda like watching Star Trek. Then it was Hi-Tek...now it's amaturish....but doesn't detrack from a great product for the day.

The key thing people need to take away from the prelim is this:

"It has been estimated that GUSTS of at least 190 mph..." Note that does not say sustained, but gusts....and estimated. We know a lot more now about the sustained/gust correlation over land than they did back in 1969. We know that you can get sustained at 150 over land and get gusts to 190...no problem. IF sustained at 190 is meant to be the thought here...then gusts of about 230-240 should be mentioned. Also notice the advisories do not say "highest sustained winds"...just "highest winds."

[wxmann_91]

those SLOSH models are out of date as Katrina proved the NHC forecasted a 15-20 ft storm surge on the MS coastline boy were they wrong

Those SLOSH runs that generated the maps for the MS Evac Zone Tool were very accurate. They were done I believe around 2000, 2001 timeframe. Let me give you just one example of their detailed accuracy. The Sheriff's sub station where my brother coordinated rescues in western Jackson County is situated on a tiny island of land off Washington Ave that only floods Cat 4 or above. When Kat's surge peaked, the sub station was surrounded by water, including water in the parking lot behind the station, and across the street. Water came up to the doorjamb but didn't come in, and there was a foot of water in the parking lot (which didn't hurt the squad cars; however all the windows were blown out of all of them so they got pretty wet on the inside anyway). That can be seen on the map. The flood levels are designed to go to down to the individual address level; you can type in your street address and find out what level of hurricane will flood your home (worst case scenario).

NHC did not forecast 15-20 ft surge.

COASTAL STORM SURGE FLOODING OF 18 TO 22 FEET ABOVE NORMAL TIDE LEVELS...LOCALLY AS HIGH AS 28 FEET ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE CENTER MAKES LANDFALL.

That proved to be correct. At the far eastern end of the MS coast, Pascagoula received 16-18 feet or surge. Surge was around 25 feet or a little higher locally where the eye made landfall. Along the shore, waves on top of the surge did additional damage (such as washing the dolphins out of their 30-ft high tank and into the GOM...where they were later all rescued). Waves on top of the surge broke down one wall of the Hancock Cty EOC, unfortunately located in the courthouse, very close to the bay, leading everyone inside to believe they were going to be drowned in the storm.

The SLOSH models were accurate - http://www.storm2k.org/phpbb2/viewtopic ... 32#1080332

[Pearl River]

If you read the first part Camilles report, it says highest winds estimated at 190 mph. Then further down it states wind gusts up to 190 mph. The advisories state winds estimated to 190 mph...not gusts. If we are going to use information, lets get the information right.

[Derek Ortt]

yes... I was saying in retrospect

what was state of the art then, is now capable of getting you laughed right off of the podium. The science has evolved greatly since 1969 and we now know that the methods used then, were not appropriate (I am sure than in 35 years, we will leanr than some of today's are also not appropriate)

[Derek Ortt]

as I've already stated, the advisories carry zero scientific weight in the scientific community

[Pearl River]

Well, if the advisories carry no weight in the scientific community, then lets throw out all the advisory info on Wilma, Rita, Katrina, Emily, Hugo and all the others.

I think there are a lot of people on this board who think they know what they are talking about, but actually have absolutely no idea.

Everyone wants to base fact on pictures they have seen or computer models they have run. No one wants to accept anything from the people who have actually witnessed it.

[MGC]

It is interesting reading the debate on Katrina by many people who live hundreds if not thousands of miles away from the Louisiana, Alabama and Mississippi coasts. I was not here during landfall, I evacuated. All I can offer is observations after the fact. My house in Diamondhead Mississippi is on a sand dune which rises from the banks of a bayou which eventually drains into Bay St. Louis. My house is 37 feet above sea level according to a map I purched from the US geological service. The debris line on the road was within 2-3 feet from the top of the dune. As the bayou is rather narrow I don't suspect there was much if any wave action affecting the surge. FEMA said there was 35 feet and my own personal observation confirms this. True the SS scale is wind based only. But Katrina smashed any records of surge observed. Anyone claiming differently simply are ill informed. As far as wind damage is conserned, I have seen my share of damage from landfalling hurricanes in my nearly 50 years. Katrina ranks right up there as a solid Cat-3 IMO. Damage in western Harrison County and Hancock County where the eyewall passed over is substanial. I've observed roofs blown off houses that were recently constructed well off the beach. Katrina had wind. Thankfully Katrina sucked in some contintial air just off the Louisiana coast and was weaking as she approached the coast. I'd hate to see what she would have done as a 5......MGC

[Margie]

Pearl River...when a met is saying the surge or wind was at a certain level, they are not saying damage did not occur. They are saying this is the scientific name for the level of the damage that did occur.

This year the media has very effectively dampened the cat scale in the public mind. Now everyone thinks that if any damage at all occured it must be labeled very high on the scale: Cat 3, Cat 4, Cat 5. Super-sizing works with fast food but not with assessing hurricane damage.

mgc...I have found topozone.com to be very accurate.

The measured high-water mark at the location where that section of Diamondhead faces the bayou was 21.7 ft:

http://www.fema.gov/hazards/floods/reco ... _ms-i9.pdf

The extent of the flood line there follows the 20-ft elevation line on topozone fairly closely.

The small area to the south of the golf course facing I-10 was flooded directly from the bay. This was one of the areas that did receive the highest level of surge, just over 25 ft.

There was no area receiving 35 feet of surge in Diamondhead.

I remain extremely interested in the surge and have tracked down many pieces of information in the news and kept track of quite a few numbers the past months, prior to any official numbers. One thing I have found with not a single exception: no one seems to have an accurate figure on how high their home is. I have taken every surge/elevation number from every newspaper story or other source, wherever I found it, used white pages and mapquest to locate the home, and then used topozone to find the elevation. Every single stated elevation has been 10-15 feet higher than it actually was, grossly inflating the estimate of the surge height. This includes articles from the Sun Herald, the MS Press, and the Jim Cantore story that went around on the Monday of the landfall (he was supposedly in a building right on the coast at a 27 ft elevation receiving 10 ft of surge), my own mother thought her home was at least 10 feet higher than it was, and she lives right next to a bayou, a friend who was left with a slab facing the GOM next to Edgewater Mall...the list is quite long.

When the numbers came out on the FEMA maps, I wasn't surprised, because they tallied with the picture I'd been able to build up from what figures I could find across the coastline.

Someone was talking today about flooding in Slidell. They mentioned flooding from Lake P. I wouldn't be at all surprised if some surge came all the way in from GOM and past Lake Borgne, up the river basin, and was pushed in overland from the east, by the eyewall winds, in addition to flooding from the direction of Lake P. The MS FEMA maps show the extensive flooding in the river basin there.

[Air Force Met]

Well, if the advisories carry no weight in the scientific community, then lets throw out all the advisory info on Wilma, Rita, Katrina, Emily, Hugo and all the others.

I think there are a lot of people on this board who think they know what they are talking about, but actually have absolutely no idea.

Everyone wants to base fact on pictures they have seen or computer models they have run. No one wants to accept anything from the people who have actually witnessed it.

I don't think you are understanding what is being said. An advisory is just a preliminary estimate. The final post analysis of the storm is done later on when the storm may stay the same as listed in the advisory...upgraded or downgraded. Some years you will see a no name tropical storm tucked in between or before a named storm because it wasn't a storm on the advisory. Why is it now? The advisory doesn't carry any real weight when it's all said and done...the post-analysis does and that's what is put in the books. The advisory is a first educated guess with all available data.

And witnessing something doesn't add data. Data is data. Facts are facts. Memories fade...memories increase. Memories aren't exact. That's a fact. Experience adds to perception...that's also a fact. That's why people who went through Camille will argue till their dying day that it was this or that. We're people and my storm is worse than you're storm. It's always been like that. That's why scientists like to stay with data and facts...and even those can lie. There are lies, damned lies, statistics....and personal experiences.

[Pearl River]

Margie. The problem I have is everyone wants to base their opinion on a few satellite and radar pictures, along with what is shown on the news. You have to see the actual damage to fully understand.

I am no means an expert, but I have seen my fair share of hurricanes starting with Hilda in 1964. The NHC based their change of Andrew on a lot of things, mostly going above ground and seeing the devestation first hand. Thats what needs to be done here with Katrina. If you look at this NCDC report, you will see that the highest winds reported from Slidell were 39 mph. NO WAY!!!!!

As I have stated in other posts, building codes here are stricter than in Florida and are able to withstand the stronger winds. Just because many houses were not flattened by the wind, does not necessarily make a weaker storm.