Katrina H-Wind Analysis, marginal 3 at landfall

[cycloneye]

Cleaned.

[dhweather]

I'm not a meterologist.

I do not play one on TV.

I didn't stay at a Holiday Inn Express last night.

But I will tell you from first hand damage that the winds were cat 4,
and the surge was cat 5 PLUS. NOAA has told insurance companies that
Pass Christian/Bay St. Louis had a surge of 35 to 40 feet. Diamondhead
had 30-35, easily. When water comes inland up to 8 miles, that's no
regular storm surge.

Washington Parish, Louisiana - the parish president was on WWL a week
ago or so. He stated that "75% of all trees are down in the parish,
100% down in many large areas. I've never seen anything to beat it.
Nobody has seen anything like it"

I've stated before - the Diamondhead Fire Department anemometer failed
at 146MPH. Mine went at 60MPH because some flying debris smashed it
early on.

I just hooked up my Davis Vantage Pro II to replace my Katrina-destroyed
Davis Vantage Pro.

[jasons2k]

Hey DH,

I am so glad you are up and running again!!

Aside from the anemometer reading, the description is more a testament to the size of Katrina rather than pure intensity.

A cat. 3 is going to bring down trees in large numbers. Normally it would be in a smaller area. The fact that it got 75% in the whole parish does not mean the winds were more intense (Cat. 4), but rather an example of just how large and widespread the windfield was. That, in turn, resulted in the massive surge as well.

[Brent]

There's no question Katrina had the surge of a Cat 5... there's no disputing that. Afterall, it WAS a Cat 5 until 12 hours before landfall. I still question these wind measurements though. I do believe it was a Cat 4 when it hit the LA coast... HOWEVER... it would have weakened some and I believe it was a Strong 3 for the 2nd landfall.

[gratefulnole]

Structural wind damage is not due to just windspeed but also how long it is exposed to those winds and the how strong the gusts are that affect a particular structure. Additionally tornado damage must be taken into account.
100 mph winds for 3 hours can possibly due more damge than 120 mph winds for 30 minutes.

[TS Zack]

I just got back from Grand Isle, La. The wind damage is horrible. I have never seen anything like it. My grandpa compares it when he went to Waveland after Camille. Entire camps are flipped like toys. There is just nothing left.

Also, I talked to the Coast Guard at the station on the end of the island and they said they reported sustained winds of 145mph with Gusts to 180mph. Take it with a grain of salt but thats just what the Coast Guard told me.

[LAStorm01]

I just got back from Grand Isle, La. The wind damage is horrible. I have never seen anything like it. My grandpa compares it when he went to Waveland after Camille. Entire camps are flipped like toys. There is just nothing left.

Also, I talked to the Coast Guard at the station on the end of the island and they said they reported sustained winds of 145mph with Gusts to 180mph. Take it with a grain of salt but thats just what the Coast Guard told me.

How about instrument failure. I heard some of the NOAA instruments were lost and so there was no longer data to post... instrument failure could have something to do with 'real-data'.

[Charles-KD5ZSM]

I have observed CAT4 damage, no doubt about it. This is not from the surge either.


Great reply, ivanhater. Alot of the catastrophic damage in MS/AL was the surge with 10 to 15 foot waves on top of that. Louisiana suffered from the breaches in the levees. P"Cola suffered hurricane force wind damage. Gulf Shores sustained damage also from the surge.

Got that right. I did a damage assesment for Harrison County Civil Defense. I couldn't fit the report into one whole radio transmission.

[Dave C]

Before this thread get's locked I'll post my thoughts. After watching Jim Leonards footage from Slidel(mostly west eyewall) there seemed to be very impressive gusts, Jim estimated 140mph gusts and he's been through countless hurricanes and typhoons. The sustained winds seemed considerably less but those impressive gusts could definately do much damage. Surprisingly, in the southern eyewall the winds and rain were pretty impressive though somewhat less than the first part indicating the southern eyewall was re-developing on landfall. Always interesting to debate scientific data.

[Aslkahuna]

To Scorpion re rapid decrease in windspeeds in hurricanes. Anyone who tracks EPAC hurricanes knows just how fast a full blown hurricane can croak when the dynamics and other conditions favorable to its maintenance go south. Same for storms in CENPAC (or in the ATL when they hit the Great Wall of Shear). In fact, JTWC has documented cases where full blown typhoons (one a Super) became TDs in 24-36 hours due to shear. For all their ferocity and power, hurricanes are actually very delicate and if conditions become unfavorable they can very quickly lose intensity.

Steve

[TS Zack]

http://pg.photos.yahoo.com/ph/zackety/my_photos

Maybe so Lagal! From what I seen from the Western Eyewall. I and everyone else in Grand Isle lost everything. I don't see this being no 3, maybe stronger than a 4.

Either way you put it. Everything is gone.

[jasons2k]

http://pg.photos.yahoo.com/ph/zackety/my_photos

Maybe so Lagal! From what I seen from the Western Eyewall. I and everyone else in Grand Isle lost everything. I don't see this being no 3, maybe stronger than a 4.

Either way you put it. Everything is gone.

This is in no way meant to diminish what happened there and those who lost everything, but those pictures don't show Cat. 4 or 5 wind damage. Roofs on the buildings, in some cases the metal roofs not even peeled off. Windows still intact, etc.

They look nothing like Homestead in 1992.

[TS Zack]

Being in the Western Eyewall, I think that is pretty darn horrible. I could see if it was a direct hit on Grand Isle.

What I don't understand is where did all these camps go? Walking around, I saw peoples lives everywhere. A Pictures From here, coffee mug, pots, toothbrush, and toys. We had a road sign from Mississippi under our camp. That I couldn't believe. Also, talking to a friend, a lady called him and said she found his seadoo in Holly Beach.

[jasons2k]

Surge, the most massive surge we have seen. The sea-doo wasn't blown to Holly Beach.

I make these comments with a heavy heart. I can't imagine the heartache and distress. But I'm just trying to be accurate.

[LAwxrgal]

What exactly is SFMR and how accurate is it?

The data I've seen says it was already at 125 mph (which is Cat 3 status) at its 3rd landfall on the MS coast.

[artist]

the damage seemed to be hit and miss as well. Wonder if there were tornadoes? Some of that reminds me of tornado damage - it skips, etc.
.

[LAwxrgal]

the damage seemed to be hit and miss as well. Wonder if there were tornadoes? Some of that reminds me of tornado damage - it skips, etc.
.

I've heard there were mini-vortices, which were mini tornadoes, which caused the wind damage that took place. Now, I wasn't here for Katrina, I had skipped town so take what I say with a grain of salt.

[donsutherland1]

LAwxrgal,

SFMR's reliability in major hurricanes is questionable.

[LAwxrgal]

LAwxrgal,

SFMR's reliability in major hurricanes is questionable.

Okay, gotcha. Is it the same thing as HRD? Or is HRD something different, and therefore more accurate?

[wxmann_91]

There is just no way to completely accurately measure wind speeds.

SFMR had problems just a day before landfall, so it isn't out of the realm of possibility that it had problems during landfall also. Damage reports can be conflicting due to localized stronger gusts and vortices, and the fact that Katrina was a large hurricane. Even anemometer measurements are questionable because they can be above the ground or they measured a gust. Recon was in Katrina but something broke just before landfall that recon wasn't able to measure flight-level winds, and even then, the reduction rate is tricky. Doppler velocities can be inaccurate also.

So, any way you cut it, I'd have to say that the NHC estimate is pretty good, Cat 4 at LA landfall, borderline 3/4 at MS landfall.