Katrina H-Wind Analysis, marginal 3 at landfall

[Stormcenter]

there was recon data right at the time of MS landfall, and it did not come close to justifying a cat 4 since the 90% reduction did not apply.

Aloft this was a cat 4 at both landfalls, but it appears as if these winds were only transported to the ground in gusts, not sustained winds, as often occurs in weakening hurricanes

I still don't understand what are you trying to justify, Cat 3 in Miss or Cat 3 in Buras?

I've been off this board for 4 days and I come back amazed to see this post is still going on. It can only mean one thing. You guys need to find a job. But seriously, why waste and mean waste so much time posting about something that you are NOT going to change anyones feelings and beliefs about. Derek you can't post it until you are blue in the face about why you believe Katrina was a Cat.3 but I and MANY others will always believe otherwise and you will not change our minds no matter what scientific reasoning you post. I think the damage and pressure speaks for itself. I'm not into the wind and pressure correlation thing. As to the article from the NHC concerning Katrina possibly being "Only" a Cat.3 storm at landfall. Well all I can say is wasn't this the same NHC that said Andrew was a cat.4 at landfall and then came back several years later to change their minds?

[f5]

the only landfall up for debate is the Louisiana landfall.

It is an accepted fact by the scientific community that MS was hit by a category 3 hurricane.

The debate is did Louisiana receive a cat 3 or a cat 4

the problem is this hurricane had CAT 5 surge while the SS scale says 9-12 ft

[TS Zack]

the only landfall up for debate is the Louisiana landfall.

It is an accepted fact by the scientific community that MS was hit by a category 3 hurricane.

The debate is did Louisiana receive a cat 3 or a cat 4

Which we will never know!!!!

Nobody in the right state of mind here with us today was at the Mouth of the River.

Being in the Western Eyewall, I see the damage, which is all wind damage. I recieved Category 2 sustained winds...

By the way, after school today I took a ride into New Orleans. Total destruction....Building burned to the ground, others collapsed. Everything needs to be torn down. Places that were dry had significant wind damage. Probably worse than my area because they were closer to the lake.

God Help These People And The Rest Of New Orleans Get Through This. Not to mention, the entire US.

[john potter]

Derek, I absolutely respect scientific evidence, and you have provided an illuminating tutorial of Katrina's dynamics in this thread. Examining vapor imagery the the Mobile radar at MS landfall bears out a weakening Katrina with declining convection and vertical motion. Generally, Katrina was cat 3 at MS landfall -- and yet, on Mobile radar, I did observe a flare of convection in the northern eyewall and a briefly reclosed eye at MS landfall. Might Katrina have briefly delivered one-minute sustained cat 4 velocities (not vortices) in certain isolated areas -- that might explain the extreme wind damage (above the surge line) continually being described here?

[jazzfan1247]

I've been off this board for 4 days and I come back amazed to see this post is still going on. It can only mean one thing. You guys need to find a job. But seriously, why waste and mean waste so much time posting about something that you are NOT going to change anyones feelings and beliefs about. Derek you can't post it until you are blue in the face about why you believe Katrina was a Cat.3 but I and MANY others will always believe otherwise and you will not change our minds no matter what scientific reasoning you post. I think the damage and pressure speaks for itself. I'm not into the wind and pressure correlation thing. As to the article from the NHC concerning Katrina possibly being "Only" a Cat.3 storm at landfall. Well all I can say is wasn't this the same NHC that said Andrew was a cat.4 at landfall and then came back several years later to change their minds?

Well it is quite unfortunate that you aren't going to change your mind. This is something that is very well worth trying for though, as it is important for people to understand exactly how strong Katrina was at landfall, as well as the reasoning behind that conclusion. This kind of "you can't change our minds" attitude is exactly what gets people killed in the first place, when they don't evacuate as they should.

Again, this has been reiterated over and over, but the damage...yes we all know it was on a huge scale. But the amount and degree of damage and the actual intensity of a storm can differ significantly, especially in this case where you have a Cat 5 surge, and a Cat 3 with a huge windfield.

[Derek Ortt]

probably not.

An explosion of convection does not always mean intensification as an Olivia study from 1994 indicated that in cases where shear increases, as appeared to happen with Katrina, convection can increase. It increases the wind gusts, while the sustained winds decrease as a whole

Weatherfreak, the evidence is posted in the first post of the thread, an objective wind analysis, which also includes the maximum observed wind, which it states is via dropsonde

[Derek Ortt]

that surge height is based solely upon values expected for south Florida, not the entire coastline

At Cayman, a cat 5 surge is 8-10 feet. In Broward county, a cat 5 surge is the same, for Miami and the keys, its what's listed in the SS Scale

[timNms]

I think Camille will be downgraded from 190 mph to 175 mph.

I still think thats too high.
The damage pics from Camille and Katrina are pretty similar.

But...the damage is from WATER....THE STORM SURGE.

Camille was atleast 175 mph = 20-25 foot surge
Katrina was 175 mph = 20-30 foot surge (KATRINA WAS LARGER)

Well show me wind damage from Camille and Ill shut up. All trees are standing, most have their foilage, and like Katrina most of the damage appeared to be from surge. Id venture to say Katrina was the Camille of this century, only larger and somewhat weaker. And I think Katrina's surge was between 25-35 feet....the waterlines on the MS coast are awfully high (in the 30 foot range).

Most have their foliage? All trees are standing? Say what? Are you talking about Camille or Katrina?

For Katrina, nearly every non-pine was denuded in Hancock, Pearl River, and Harrison counties on the coast, to points well inland and not harmed by surge. The standing trees are usually live oaks, or smaller, more flexible pines. Since the storm a lot of the non-pine trees have had a winter bloom of sorts and have leafed out like mad (it's a crazy sight).

For Camille--most of the standing trees again were live oaks or the smaller pines.

And regarding inland damage in general and only in reference to Katrina: the tree and home damage due to wind all the way up to Laurel, MS is impressive...we're talking wind-abraded roofs and probably 30-40% of trees downed. Laurel is 90-100 miles inland. For instance, look at central Diamondhead (where elevation peaks on the coast) and more than half the trees are snapped in half or uprooted due to the wind, not the surge.

Yep, spring-green colored trees in fall...strange sight to see, but if one pays a visit to south Mississippi, that's what one will see! Katrina stripped all the leaves and needles off of the trees in this area. Now they're confused and putting on new ones!

[TS Zack]

Most of the trees along the coastline will never gain their leaves back.

[Droop12]

Same thing happened after Ivan, by Nov. all the trees were green again. It was a very odd site.

[Weatherfreak000]

probably not.

An explosion of convection does not always mean intensification as an Olivia study from 1994 indicated that in cases where shear increases, as appeared to happen with Katrina, convection can increase. It increases the wind gusts, while the sustained winds decrease as a whole

Weatherfreak, the evidence is posted in the first post of the thread, an objective wind analysis, which also includes the maximum observed wind, which it states is via dropsonde

But it was been said over and over in this topic that isn't a very reliable substantial base of proof.


Am I wrong to believe what you posted was just preliminary observations and would this be backed by the NHC completely?

[dhweather]

Derek, I absolutely respect scientific evidence, and you have provided an illuminating tutorial of Katrina's dynamics in this thread. Examining vapor imagery the the Mobile radar at MS landfall bears out a weakening Katrina with declining convection and vertical motion. Generally, Katrina was cat 3 at MS landfall -- and yet, on Mobile radar, I did observe a flare of convection in the northern eyewall and a briefly reclosed eye at MS landfall. Might Katrina have briefly delivered one-minute sustained cat 4 velocities (not vortices) in certain isolated areas -- that might explain the extreme wind damage (above the surge line) continually being described here?

That is my belief. Right as Katrina approached Mississippi, deep
convection developed in the northeast quad of Katrina's eyewall,
and slammed ashore from Waveland to Long Beach, MS.

And I too find it strange to see fresh green leaves on trees in the fall.

Our crape myrtles were stripped clean and pushed over. I propped them
all back up, they all re-leaved themselves, and bloomed again.
Weird man, weird.

[MGC]

Dereck, have you seen any vertical wind data? If so, could you post it here. Also, where in Katrina was recon at the MS landfall? In the eye or on the periphery? Are we relying on a sonde or flight level winds using the mean reduction factor? The flareup of convection at MS landfall was quite evident and suggests to me that Katrina was shaking off the dry air she had gulped. Andrew continued to intensify a short while after landfall and it is possible (but remote) that Katrina could have been intensifying a bit at her 3rd landfall in MS........MGC

[HurryKane]

Most of the trees along the coastline will never gain their leaves back.

Sure they will. A lot of them already have.

[Derek Ortt]

the maximum winds according to the NOAA sondes was 101KT. Some air force sondes had higher values, but they failed at about 80m. The wind decreases logrithmically in near the surface, so a 125KT wind at 80m, may only be 100-105 at 10m. The NOAA sondes did record to the surface.

I will soon look at Katrinas sondes as part of the RAINEX data analysis, since many of those sondes are ours (though not from landfall per say). I will take a quick look at the vertical velocities and compare them with the day before.

At MS landfall, I believe recon got into the NE quad just before landfall, and found 127KT, which usually equates to 115KT. However, all available evidence suggests that the mean 90% did not apply, as it did not for Ivan. The 90% or hgiher tends to occur where the oceanic heat content is very high just offshore, which is not the case for most of the NGOM

[Scorpion]

What about the 233 kt wind at about 1800 ft recorded? That would yield 186 kts at surface. I wonder if the winds were stronger than 175.

[senorpepr]

What about the 233 kt wind at about 1800 ft recorded? That would yield 186 kts at surface. I wonder if the winds were stronger than 175.

That was ruled as bogus.

[dhweather]

Even if only 20% (not the more than 50% reported by the Miami Herald)
of the sondes are bad, then we likely have a lot of bad data for every
storm they've dropped them in. Not just one anomoly, as in this case, but
several wind reports that were much lower or higher than they
actually were.

[MGC]

Thanks Dereck and keep us posted on any new information you find out about. The 70% reduction is the norm when a TC is interaction with land, right? 90% over open tropical waters. It will be interesting to see best track. My eyes are telling me this is upper Cat-3 compared to what I've observed in the past going back to Hurricane Betsy. If Katrina was indeed a week Cat-3 then the HRD boys need to look at historical landfalls and reanalsys is in order. The SS scale need to be changed also. I would have stayed for a Cat-3 considering I've been through Betsy and the NWS measured Cat-3 winds in New Orleans before the instrument broke. I guess I'll have to rethink my evacuation plans based on Katrina.....MGC

[wxmann_91]

What about the 233 kt wind at about 1800 ft recorded? That would yield 186 kts at surface. I wonder if the winds were stronger than 175.

That was ruled as bogus.

Even if it was not bogus, the 233 kt was a gust and not a sustained wind, so it is entirely possible.