Katrina H-Wind Analysis, marginal 3 at landfall

[Derek Ortt]

ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2 ... l02deg.png

about 6 hours before landfall

Don't shoot the messenger here, but this is what an objective surface wind analysis from NOAA-HRD has found

ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2 ... l02deg.png

at first landfall

ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2 ... l02deg.png

at final landfall

based upon the HRD suirface wind analysis, a very unpopular on this board result of Katrina being a marginal cat 3 with 100KT winds at landfall, weakening from a 4 just 6 hours prior may have been what Katrina was at landfall, and I have heard that a doppler analysis may back up the H-Wind results

Still, shows that ANY major hurricane must be taken extremely seriously, and because Katrina moved over the shelf water as a very strong 4, the tidal surge had already started to pile up, unlike Opal, which was a 4 just before hitting the shelf

[cjrciadt]

Whoa we all know the W quad was shambles at landfall this shows lower winds does not mean lower surge.

[Anonymous]

ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2005/al12.2005/0829/0430/col02deg.png

about 6 hours before landfall

Don't shoot the messenger here, but this is what an objective surface wind analysis from NOAA-HRD has found

ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2 ... l02deg.png

at first landfall

ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2 ... l02deg.png

at final landfall

based upon the HRD suirface wind analysis, a very unpopular on this board result of Katrina being a marginal cat 3 with 100KT winds at landfall, weakening from a 4 just 6 hours prior may have been what Katrina was at landfall, and I have heard that a doppler analysis may back up the H-Wind results

Still, shows that ANY major hurricane must be taken extremely seriously, and because Katrina moved over the shelf water as a very strong 4, the tidal surge had already started to pile up, unlike Opal, which was a 4 just before hitting the shelf

I actually believe the landfall intensity has been adjusted to 125 kt...rather than 120 kt.

[Brent]

WOW... that's amazing.

[Ivanhater]

well ivan was a "moderate" 3 close to a 4 at landfall and look at the devasation he casued

[HurryKane]

WOW... that's amazing.

And I have to tell you...a lot of people who live down here disagree heartily with the results...particularly when looking at the sustained winds where they live/lived.

[DESTRUCTION5]

No biting here...She was a 4 hook line and sinker...When you drive 2X4's thru trees and bring wather 12 miles inland you dont call yourself a 100Kt Storm..

[curtadams]

Are these true ground level winds or 10 meter up reference surface level winds?

[djtil]

wind damage seems to correlate well with these results.

[jax]

Are these true ground level winds or 10 meter up reference surface level winds?

I sure hope some of the destruction goes away here when they officially
downgrade... (that would be cool!)

[Ivanhater]

guys, i heard the same thing about ivan after landfall and were STILL getting our lives back together....let it roll off your back cause these people can sit at their computers and digest data while we rebuild our lives and try to pick up the pieces, these people will never know unless they lived in pcola or misissippi or louisiana.....so let them go around and say it was ONLY a 3 and sit at their desk while we rebuild our communities...this is my opinion and people can flame me, but you will never know unless you have been through a major devastating event like some of us on this board have

[Lindaloo]

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.

[curtadams]

I sure hope some of the destruction goes away here when they officially
downgrade... (that would be cool!)

The damage is real. So are the wind measurements. The required conclusion is that sustained 100 knot winds (or perhaps associated gusts) can cause what people call Cat 4 damage.

[Brent]

It's hard for me to tell what intensity this was because along the coast everything was destroyed by the surge, I will say this, I didn't see the type of wind damage we saw after Charley or Andrew, which pretty much told me if it was a 4, it was a low end 4, HOWEVER, I also didn't see any wind damage AT ALL from the 1st landfall, so that above just pertains to the MS coast. If someone has pictures of Cat 4 wind damage in MS I'd love to see them.

[Javlin]

Let's see I have been through Camille,Fredrick,Elena,Georges and Katrina.I can say without a doubt for all those who have endured Katrina has been by far hands down the most exhaustive hurricane I have ever been through.The wind damage exceeds all others by far. If Katrina was only a marginal 3 then some of the others were Cat 1s.Unless you have walked the streets here I think djtil it,s hard to get afeel for the damage by photos alone.I have talked to people who came in days after and said it much worst than ones perception from TV and pictures.

[skysummit]

I sure hope some of the destruction goes away here when they officially
downgrade... (that would be cool!)

The damage is real. So are the wind measurements. The required conclusion is that sustained 100 knot winds (or perhaps associated gusts) can cause what people call Cat 4 damage.

Another two letters....BS
There have been homes and business completely obliterated well WEST of the center. Sorry to say, but some people actually know the differnece from cat 3 damage and cat 4 damage.

[Lindaloo]

It's hard for me to tell what intensity this was because along the coast everything was destroyed by the surge, I will say this, I didn't see the type of wind damage we saw after Charley or Andrew, which pretty much told me if it was a 4, it was a low end 4, HOWEVER, I also didn't see any wind damage AT ALL from the 1st landfall, so that above just pertains to the MS coast. If someone has pictures of Cat 4 wind damage in MS I'd love to see them.

When I have time to get them developed I will be happy to. I was an adjuster for a long time and I know the difference between storm surge damage and wind damage further inland.

FWIW, some of the damaged homes along the coast of Pascagoula was also not only due to storm surge but also wind damage.

[Lindaloo]

I sure hope some of the destruction goes away here when they officially
downgrade... (that would be cool!)

The damage is real. So are the wind measurements. The required conclusion is that sustained 100 knot winds (or perhaps associated gusts) can cause what people call Cat 4 damage.

Yeah, they said this same thing after Andrew who was a CAT4 right? They changed it 10 years later.

[patsmsg]

Two letters.......... BS

Ditto. Absolutely NO way.

I was no where near any water, and the wind tore the hell out of everything. Before you jump in to say it doesn't take cat 4 winds to destroy things, I know that. I was here for Camille, Frederic, Elena, Georges, et all. I've been there ok?

The winds were definitely higher than they are depicted here. It's a moot point though. I'm not an idiot who gets a kick out of bragging about the strong winds that hit us, so I don't care what anyone says they were. The damage is what it is, and I KNOW the winds were higher than depicted by NOAA.

If a truck runs me over, but you say it was a VW bug. What do I care? I'm still road kill.

[tallywx]

Derek, has SFMR (which is what these max. winds are based upon) been tested or adjusted to waters of varying viscosities? I know the technique that such instrumentation utilizes, having done research with COAPS leading up to the QuickScat launch. My assumption is that SFMR is similar...uses microwave radiation to measure sea state conditions (chiefly ripples on the sea surface), which can then be correlated well with how strong winds are blowing at the surface (because ripples respond more spontaneously to winds than say larger waves).

However, it would seem that near shores and especially in areas of ocean water that contain a lot of sediment (e.g. the Mississippi Delta area), it would take more wind to achieve the same amount of "ripple." For example, take a very viscous solution like molasses in a cup and try blowing on it to make ripples. Impossible, right? So on a less extreme level, it would seem that ocean water higher in silt content would take a greater amount of windspeed to produce a given level of ripple. Maybe this is why SFMR perhaps is underestimating surface winds in Katrina.

Also, since SFMR measures surface winds (winds actually acting on the ocean surface itself), wouldn't an upward adjustment be required to obtain standard 10m height winds?