By: ncforecaster , 6:55 AM GMT on August 30, 2007

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Hey everyone,

I want to begin this particular blog entry by personally thanking each and everyone one of you who has taken the time to read and/or post in my previous couple of blogs (many of which have been long time friends from this wonderful community). I have chosen to commemorate the two year anniversary of hurricane Katrina's catastrophic landfall along the northern U.S. Gulf Coast by discussing the significance of hurricane Katrina's true landfalling intensity when it barrelled ashore. To be most specific, I want to share a most fascinating and interesting independent reanalysis by Captain Ronald E. Hughes, USN (Retired). It is an absolute must read for anyone interested in knowing just how strong hurricane Katrina may truly have been when she struck the Northern Gulf Coast. This reanalysis makes a very strong case that the NHC inadvertinly misinterpreted the available data which survived the storm. In doing so, they unjustifiably reclassified hurricane Katrina as only a 120-125 mph category three in their subsequent post storm reanalysis. As many of you may recall, I have consistently felt the NHC's post operational downgrade and their subjective rationale did not adequately explain nor correlate with the measurable components regarding this powerful storm. They had to rewrite the meteorological record in trying to justify how the third most intense storm in U.S. recorded history (920 mb) with the largest recorded storm surge to ever impact the U.S. shoreline (measured at 28 feet along the Mississippi coastline) was merely a 120-125 mph category three at the two respective Gulf Coast landfalls. It is also important to note that the barometric pressure had risen to a still remarkably intense 927 mb as Katrina's eye officially came ashore near the La./Mississippi border bringing with it the immense and historic 28 foot storm surge.

At face value, the two respective barometric pressure readings at landfall would typically equate to a high end category four storm (the La. reading being a borderline category pressure). As far as the recorded storm surge is concerned, it is in a category all by itself. Only the second most intense landfalling hurricane to ravage U.S. shores (category five Camille) has produced a storm surge within comparable range of hurricane Katrina's. It is also important to note that category five storm surge is characterized as being greater than 18 feet (a full 10 feet below the astonishing value register with Katrina). Although, this data would otherwise imply that Katrina could have been declared a category five at landfall, there are other important meterological intangibles that conspired to strip hurricane Katrina of that classification (where it stood operationally only 5 hours prior to La. landfall) in complete objectiveness. As we know, Katrina was gradually weakening during the last 14 hours prior to making landfall (barometric pressure rose from 902-920 mb) along the extreme La. shoreline. This weakening began shortly after huricane Katrina had obtained her peaked intensity while registering a barometric pressure of 902 mb accompanied by maximum sustained winds of 175 mph as she began to undergo a significant structural change known as an eyewall replacement cycle.

In simplest terms, it is the process where an outer eyewall develops from powerful convective rainbands merging together around the single smaller (i.e. inner eyewall) eyewall that had previously existed before the process began. As a result, the inner eyewall begins to weaken as it's energy is being zapped by the newly formed and intensifying outer eyewall. Once this process reaches completion, the inner eyewall will have completely dissipated, and the storm will once more retain a single eyewall. The major difference being that this newly formed eyewall is much larger than the one that preceded it. Consequently, the larger eye coincides with a larger pressure gradient (difference in wind speeds over a given distance) whereby the storms top winds will decrease. Depending upon the other atmospheric parameters in play (i.e. atmospheric conditions such as vertical wind shear, water temperatures, proximity to land, dry air infiltration, etc.), the storm can and often times reintensifies. This occurs as the new single eyewall shrinks in size, which enhances the pressure gradient whereby the top winds increase once again (given the right conditions, to an intensity greater than before). Moreover, these EWRC most often coincide with an overall broadening of the wind field and overall size of the storm itself. In the case with hurricane Katrina, she began an EWRC roughly 14 hours prior to La. landfall that saw her barometric rise to 920 mb and the top sustained winds of 145 mph operationally. In addition, she expanded her wind field to where hurricane force winds extended outwards 125 miles from the center of the eye from the 105 miles prior to the onset of the EWRC. This weakening trend was also aided by the intrusion of dry air as it drew closer to land as well as slightly cooler water temperatures nearer the coastline. Furthermore, an increase in wind shear and the intrusion of dry air be the main culprits that caused the observed erosion of the inner eyewall on the SW side as it was coming ashore. Given all of the aforementioned evidence, the official operational landfalling intensity of 140-145 mph (strong category four) seems most logical.

In short, this very large category four hurricane that only 14 hours earlier retained 175 mph category five intensity, would better explain the record 28 foot storm surge that battered the Mississippi coastline, as well as how she was able to deliver such extensive wind damage some 150 miles inland. These inland effects consisted of the equivalent of F2 type tornado damage more than 110 miles from the shoreline. This wind damage was the result of measured wind gusts exceeding 120 mph in Laurel, Mississippi (located 110 miles from the shoreline). Naturally, the wind damage became increasingly more extensive as one got closer to the coast where Hattiesburg had wind gusts estimated at 125-130 mph (70 miles inland), and Poplarville (50 miles inland) recorded a peak gust of 135 mph (before the anemometer was destroyed by the powerful winds). Since most anemometers were either disabled or destroyed before the arrival of the peak conditions associated with the storm, the NHC had very little and very incomplete measurable wind data to assist them with determining the highest maximum wind speeds that were truly experienced along the coastline for the two respective Gulf Coast landfalls. As a result, much of it was left to conjecture and subjectivity, in order to best theorize how strong the winds might actually have been.

As noted earlier, the independent reanalysis alluded to earlier (with link provided) discusses how the NHC apparently misinterpreted the data that existed. Most notably, they apparently didn't recognize the presence and true intensity of the outer eyewall which had intensified, but not weakened the inner eyewall as first suggested by the NHC report. This was the result of Katrina's EWRC being halted prematurely by its interaction with land. Thus, Katrina was able to retain more intensity (i.e. not as much weakening as suggested in the NHC post storm reanalysis) when she made her catastrophic and historic landfall. The author of this report argues that hurricane Katrina's category five wind gusts destroyed many structures that were virtually left unscathed by Katrina's storm surge. Likewise, He provides documented evidence to support this assertion that suggests Katrina's powerful winds from the outer eyewall destroyed many structures well before Katrina's massive storm surge reach the shoreline. For countless individuals and families still homeless (or living in Fema trailers) and the thousands who have had their insurance company refuse to fulfill their commitments to help them rebuild (declaring their homes were destroyed by flood damage from the storm surge) by referencing the NHC revised 120-125 mph category three landfalling intensity makes a thorough reanalysis of the legitimacy of the NHC post operational downgrade most significant. Even more startling is the fact that many insurance companies are winning lawsuits to deny coverage on the basis that the NHC and its sister branches have officially suggested that only category two sustained winds impacted the hardest hit areas.


In conclusion, I firmly believe the meterological data, eyewitness accounts, and the immense observable catastrophic damage left in Katrina's wake all support the operational category four 140-145 mph landfalling intensity (for the Buras, La. Landfall), as opposed to the current revised post operational 120-125 moderate category three. In regards to the second Gulf Coast landfall near the La./Mississippi border, I would suggest that hurricane Katrina still maintained the lower end of category four intensity (135 mph), which would support the idea that 155 mph gusts (as has been estimated by various sources) destroyed beachfront homes, as expressed in the independent reanalysis. It took the NHC ten years to upgrade hurricane Andrew to a 165 mph category five at landfall in southeast Fl. from the operational 145 mph category four. In this case, one can only hope they will be more expedient in adjusting the true intensity of what appears to have been a powerful category four landfall of immense proportions. Most relevant is the fact that thousands of victims of this devastating storm are continuing to be adversely impacted more than two full years after their homes were apparently destroyed by her powerful winds, rather than water (as their insurance companies claim).


Hurricane video (estimated 155 mph gusts)
Credits go to Dave Lewison (Face the Wind)

Forrest County, MS. Inland Damage
Credits go to the Jackson, MS. NWS
Note: This is where I filmed Katrina in South Hattiesburg, Mississippi (65 miles inland)

Katrina Wind Speed Map
Credits go to "Forest One"

Report on "wind gusts underneath areas of deep eyewall convection in hurricanes katrina and Dennis at landfall"
Credit goes to Richard G. Henning (46th weather squadron, Eglin AFB, Fl.)

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16. aquak9
12:17 AM GMT on September 07, 2007
Wow, Tony. First off, great to see you still visiting. Wish you could've been here with us last saturday night- an historic evening to watch and read the blogs. Mind-numbing, to read along, as Felix unfolded in front of us. Second, excellent reading material. And I really enjoy reading everyone else's insight, seeing the different yet agreeable opinions surface for further discussion.

Certainly hope to see more of you for the rest of Season™- but if not, still good to see you around!
Member Since: August 13, 2005 Posts: 163 Comments: 25780
15. outrocket
12:16 AM GMT on September 07, 2007
Posted By: rlk at 5:34 PM CDT on August 30, 2007.

How well understood are the meso and microscale processes within the eyewall of an intense hurricane? From what I've read, mesocyclones can form within the eyewall and possibly create localized extreme winds that are not representative of the storm's circulation wind speeds.

That is exactly right now picture this in your mind...a mesocyclone In the East eye wall as the storm moves north..
First you must add the forward speed of the storm northward to the winds on the East Side..
so if the Hurricane had winds of 130 mph and a forward movement north of 15mph then you must add 15mph to the winds could be 145mph and force is equal to mass times velocity squared so every mph exponentially increases the force...
Now having said that imagine a mesocylone traveling at say 100 mph with in that East eye wall and imagine adding the forward speed to the east side of the mesocyclone it's self...:))..Thats how ANY Cat 3 storm can have the potential to have catastrophic Cat5 damage over a given area...

Member Since: July 15, 2005 Posts: 104 Comments: 11010
14. rlk
11:38 PM GMT on September 06, 2007
I finally got around to reading the whole site. Very interesting, indeed. The radar shots certainly don't look like a rapidly weakening storm.

I suspect that the assumption that hurricanes immediately begin to weaken when they make landfall is flawed. Particularly over flat, moist terrain, I shouldn't think that their moisture source is immediately cut off. If the land is warmer than the ocean, I could even see it being a source of heat for a while. And the frictional effects of land might well create local convergence near the coast (if the wind over the ocean follows the isobars while the wind over the land has a cross-isobaric component, wouldn't it yield localized convergence in the forward part of the storm?), which might make for local strengthening. Andrew was a very compact storm, but Homestead, which isn't right on the coast, got hammered. Then, of course, we have Erin, which after meandering for a while over west Texas, developed a very nice eye signature on radar over Oklahoma.

One other thing I noticed is that outer eyewall looks like it spent a lot of time near New Orleans.
Member Since: January 30, 2005 Posts: 0 Comments: 96
13. reeldrlaura
11:24 AM GMT on August 31, 2007
Tony -
Thank you for that wonderful post!!! I have friends in Buras who will tell you that the reassessment of Katrina you have posted is far more accurate that anything else to date!
Member Since: July 31, 2005 Posts: 93 Comments: 6007
12. rlk
10:34 PM GMT on August 30, 2007
How well understood are the meso and microscale processes within the eyewall of an intense hurricane? From what I've read, mesocyclones can form within the eyewall and possibly create localized extreme winds that are not representative of the storm's circulation wind speeds. Furthermore, I'd expect passage over land would create frictional effects, and it's known that tornadoes form in the right front quadrant (and wasn't Katrina quite a prolific generator of tornadoes?). That would again suggest the possibility of mesoeffects that might generate excessive localized winds.

The conventional explanation of the extreme storm surge is that the recent history of Katrina (extremely low pressure, mid to high end cat5 winds, and unusually large size) generated an unusually large dome of water for the wind speeds estimated at landfall. Also, areas particularly vulnerable to very high storm surge were to the right of Katrina's center. Even if true, however, that wouldn't be evidence that Katrina was only cat 3 at one or both landfalls.

Eyewall replacement cycle or no, Katrina's central pressure was extremely low for a cat 3 at landfall, and the high winds inland would also suggest a storm that wasn't falling apart particularly quickly. Big storms like that also don't tend to decay particularly quickly.

I'm certainly no expert on this, but this research is very interesting...
Member Since: January 30, 2005 Posts: 0 Comments: 96
11. cyclonebuster
9:57 PM GMT on August 30, 2007
Just like Andrew we will know 10 years later after Katrinas landfall!
Member Since: January 2, 2006 Posts: 127 Comments: 20396
10. louastu
9:43 PM GMT on August 30, 2007
I'm glad I caught you before you signed off. It's good to know you are doing alright. Aside from the bad sunburn I got from being in the sun for 6 hours this past weekend (reffing soccer), I am doing just fine. Anyway, very good blog. Based on that information, it definitely appears that Katrina was a strong cat-4 or possibly a "weak" cat-5 at it's first landfall.

I am happy to know that you agree with my revised forecast (I am assuming that you are only talking about my Atlantic basin predictions). I also posted a new entry in my historic storm series. The storm I posted on was 1982's Tropical Storm Beryl. I hope to talk with you again very soon. Have a great day.

Your Friend,
9. ncforecaster
9:07 PM GMT on August 30, 2007
Hey Louis,

I was just signing off for the day when I saw your very thoughtful post.:) It is always a blessing to hear from you and/or talk with you when time allows. I have been extremely busy with work and some other things gong on in my life currently. That being said, I am doing pretty well myself and I hope the same most certainly applies to you as well.

In regards to this seasons tropical activity, I was never able to find the time necessary to complete my June (seasonal) updated forecast (where I was going to adjust the overall storm totals slightly). That being said, I did take a moment to read your current blog on the subject, and I am in complete agreement on your revised figures myself. I do anticipate a pretty active September and October myself with at least one major landfall occurring this season along the U.S. shoreline. Most importantly, I want to thank you for simply being you, and I look forward to seeing you online again in the near future.:)

Your friend,
Member Since: May 17, 2006 Posts: 107 Comments: 1362
8. louastu
8:53 PM GMT on August 30, 2007
Hey Tony, great to see you! How are you doing? Going to read your blog now.
7. ncforecaster
8:47 PM GMT on August 30, 2007

To keep this as brief as possible, I can honestly say that the "Introduction" to the independent reanalysis linked and alluded to in my blog entry, truly captures the same sentiment I share on this most important matter, in my own humble opinion.


"Waterfront homes and businesses, in the tens of thousands, disappeared as Hurricane Katrina passed over the Louisiana/Mississippi Gulf coast. Returning residents found only a slab or vertical column foundation, where their home once stood. With the exception of a few heavy trinkets and automobiles, everything else was gone. Accumulations of family treasures, some over several generations, had been completely wiped out. Furnishings, possessions, heirlooms, photographs, yearbooks and computers containing family histories had vanished. Beach and waterfront activities ceased. Expensive homes were replaced by a wasteland. For most returning residents, the greatest loss was the absence of family and friends in the home, neighborhood and surrounding towns. The feeling of personal loss was staggering. To this date, many former residents still suffer from Post Katrina Stress

The only salvation was the knowledge that residents could soon rebuild. Conclusive evidence revealed that wind was the destructive force that caused residences and businesses to vanish. Most residents had Homeowner Insurance Policies that covered damage from hurricane winds. They had paid steep premiums for decades. They had confidence that their insurance companies would come to the rescue. Four months later, the U.S. Government turned their dreams into another nightmare.

On December 20, 2005, the U.S. Government officially determined that Hurricane Katrina’s winds had been too weak to blow away homes on or near the waterfront. In arriving at this conclusion, the government had to rewrite the hurricane science and history books. Residents who had their homes disappear knew a mistake had been made. They expected the government to soon realize the mistake and come to its senses. This has not happened. Eventually it will. Hopefully, it will not be too late for thousands of Gulf coast residents. With time and future research, the true story of Hurricane Katrina will be revealed. But there is no time for scholarly investigations. Thousands of Gulf coast residents cannot rebuild without wind damage insurance settlements. The statute of limitations on wind damage claims is running out. Failure of residents to receive payment, for wind damage soon, will cause the Gulf coast wasteland to go further into depression. Quality of rebuilt homes and businesses is already declining."

Most important of all, I want to encourage all of us to continue to keep those still suffering more than two years after this truly cataclysmic event, in our most heartfelt thoughts and prayers. Once again, I want to wish each and everyone of you a great rest of the day.:)

Most sincerely,
Member Since: May 17, 2006 Posts: 107 Comments: 1362
6. ncforecaster
8:37 PM GMT on August 30, 2007
Hey Sandi,

The feeling is most certainly mutual for it is great to see you again as well.:) Thanks so much for the very kind words related to my blog entry, as well as the thoughtful sentiments regarding my family. I too hope you and yours are doing well, and look forward to talking with you again in the near future.:)

Your friend,
Member Since: May 17, 2006 Posts: 107 Comments: 1362
5. ncforecaster
8:32 PM GMT on August 30, 2007
Hey Outrocket,

First, I want to thank you for your thoughtful posts as always. With that in mind, I too couldn't agree more with your assessment of the problems that are encountered when trying to categorize the uniqueness of individual tropical cyclones into one specific category. As you so well noted, this can tragically create a false sense of security for those that are subsequently impacted by these devastating storms. One only has to think about all the unnecessary deaths that Katrina took during her first U.S. Landfall as an 80 mph category one (near Miami, Fl.), that were the direct result of many thinking it is only a weak category one storm.

In reference to Hurricane Frederic, I would also suggest that the available data from Hurricane Frederic's devastating Gulf Coast landfall near Mobile, Al. in September 1979 makes a strong case that it actually came ashore as a minimal category four hurricane (as opposed to the current category three status that is officially attributed to it). With that in mind, I would not be a bit surprised to see Frederic post humorously redesignated as a category four hurricane, when the HRD completes their reanalysis for this time period in the future.

In short, I wholeheartedly agree with your post and feel that it is still most important that the actual "wind speeds" be accurately determined so that those victims whose homes were damaged or destroyed by winds aren't denied the opportunity to recover the money they have paid for decades to their insurance companies who try to find a loophole by suggesting it was flood damage from the storm surge as alluded to in the independent analysis, as well as this blog on the subject. Thanks again for your excellent post, and I hope you and everyone else has a great rest of the day.:)

Your friend,
Member Since: May 17, 2006 Posts: 107 Comments: 1362
4. sandiquiz
8:22 PM GMT on August 30, 2007
Hi Tony, lovely to "see" you again, and as usual, a fantastic and fascinating read.

Hope you and your family are well.
Member Since: October 29, 2005 Posts: 289 Comments: 26061
3. outrocket
8:01 PM GMT on August 30, 2007
We have seen this many times..Frederic in 1979 slammed the Mobile,Al area with what was listed as catagory 3 winds..However the dauphin Island bridge weather station blew away 43 seconds into a 151mph wind..did the wind actually stay that strong for another 17 seconds ???? One will never know because the bridge went down...What needs to be factored into all MAJOR Hurricanes of Catagory 3 or higher is the fact they can cause catagory 5 conditions at different locations within the NE Quad..I say drop the catgories and concider all major hurricanes capable of anything...Had some not thought Katrina had weakened below Camille ,more lives might have been saved as more would have left....
Member Since: July 15, 2005 Posts: 104 Comments: 11010
2. ncforecaster
8:16 AM GMT on August 30, 2007
Hey Kori,

"I would not, however, say it to be as strong as the 145 mph you suggest (no offense). I would think it was around 135 mph."

I need to clarify that I was suggesting 140-145 mph category four at the extreme SE La. landfall with the 920 mb pressure. As far as the second Gulf Coast landfall in Mississippi, I actually didn't specify a particular designation, but still feel the same as I did in my previous blogs on this subject (where I stated I felt Katrina was a 135 mph category four at Mississippi landfall). Consequently, I am in complete agreement with your assessment for the Mississippi landfall as well. It is obvious that Katrina had continued her more gradual weakening trend while passing over Buras. La. its eye landfall roughly 31/2 to four hours later, near the La./Mississippi border. Thus, I would extrapolate 135 mph from the 140-145 mph I believe to be the true landfalling intensity when Katrina first barrelled ashore just south of Buras, La. Simply put, I appreciate you bringing that important oversight to my attention (i.e. not specific on the Mississippi landfall intensity), and I will certainly update my blog to clarify this to include my personal opinion of her second Gulf Coast intensity, as alluded to above.

Regarding the powerful inland wind gusts and subsequent damage, I too took into account the relatively fast forward motion. That being said, Hattiesburg, MS. still experienced estimated 125-130 mph wind gusts around 130 pm CDT (a full 3 1/2- four hours from MS. landfall and a full 7 1/2 hours following the Buras, La,. landfall). In other words, these are some extreme wind gusts for a hurricane that was steadily weakening after being over land for roughly 4 hours. Likewise, Laurel, MS. officially recorded a 110 mph wind gust before the anemometer was destroyed some 110 miles inland around 2 pm CDT. These powerful winds were recorded 4-41/2 hours after Katrina was over land and steadily weakening. Obviously, the relatively fast forward motion and very large windfield were also responsible for bringing such intense winds that far inland. That being said, I still feel that these extreme inland winds are most relevant in reconfiguring just how strong the winds most likely were for areas just on the coast, when Katrina was still over warm water, while battering locations like Waveland, Bay St. Louis, and Gulfport, with winds that logically appear to have been the equivalent (in my own humble opinion) of a minimal category three (135 mph). Most importantly, I want to thank you for your excellent post, and to restate that we are in complete agreement on the Mississippi landfalling intensity (if I haven't inadvertently misinterpreted your post). I hope you and everyone else has a great rest of the night, and day ahead.:)

Most sincerely,
Member Since: May 17, 2006 Posts: 107 Comments: 1362
1. KoritheMan
7:36 AM GMT on August 30, 2007
Well, what the NHC says goes, so if we don't like it, tough. But yes, I agree that Katrina had to have been stronger than 120-125 mph at landfall. I would not, however, say it to be as strong as the 145 mph you suggest (no offense). I would think it was around 135 mph. Don't forget that Katrina was also moving relatively fast (about 14 mph) when it made its Louisiana landfall, and it may have sped up after that, but I don't remember. This fast foward speed allowed hurricane conditions to travel well inland, which probably explains the 135 mph wind gust in Poplarville. I have been up in Mississippi in early April, as far inland as Yazoo City, and I saw some evidence of damage from Katrina even that far inland, in the form of power lines that were still leaning. This tells me that at least strong tropical storm conditions impacted Yazoo City.

But again, the foward speed allowed hurricane conditions to be spread out very far inland, because Katrina didn't weaken that much. Same for Camille in 1969 -- it moved through fast, thus it was able to retain hurricane intensity very far inland. I don't think the 135 mph wind gust in Poplarville justifies upgrading Katrina to a Category 4, but I do think that it was more than likely at 135 mph at landfall, as opposed to 120-125 mph.
Member Since: March 7, 2007 Posts: 560 Comments: 20030

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