Katrina H-Wind Analysis, marginal 3 at landfall

[Derek Ortt]

seems like scorpion needs to take this issue up with NOAA, since it seems as if he is the all knowing high school student who fully understands GFD and the forces that produce the wind.

I dont agree with the findings either, but at leats know to take an open mind and investigate them seriously

[HurricaneBill]

one thing is, moist people that go through a major hurricnae, dont really go through a major hurricane

What about dry people?

But seriously, I think the Saffir-Simpson scale needs to be revised, especially for storms that weaken right before landfall.

After all, you use different reductions for flight winds at different levels.

[JTD]

seems like scorpion needs to take this issue up with NOAA, since it seems as if he is the all knowing high school student who fully understands GFD and the forces that produce the wind.

I dont agree with the findings either, but at leats know to take an open mind and investigate them seriously

This is true. Derek initially strongly believed this was a cat 4 at landfall. He posted that several times. He is just going by new data as it is released.

[JTD]

Oh whats next Rita was a strong Cat 1 at landfall?? Give me a break. This was a Cat 4 hands down. Hurricanes don't weaken 50 knots over a little dry air intrusion. People are trying to say a 918 mb hurricane is a marginal 3?

Rita was 930-933 and a strong 2 at best.

[Scorpion]

If this was 100 kt at landfall then Rita would be what 80 kt? Katrina kept the eye all the way up to landfall and was not weakening rapidly. I don't see how it could be 100 kt. Portions of interior Mississippi were heavily damaged as well, and if Katrina was 100 kt at Louisiana then it would drop down to 60-70 kt by the time it was well inland. And that wasn't the case. If Katrina was 100 kt in Louisiana it would be 90 kt max at the MS coast.

[Derek Ortt]

and the 90 percent rule is not a rule as NHC uses it as, it represents an average reduction.

In stratiform storms like Rita and Isabel, the reduction is closer to 75-80% bue to weaker up and downdrafts, while in storms like Bret, the reduction is 115%

maybe what we could do is include the size of the windfield, but I am not sure how to quantify this. Would have to think much harder about how to quantify this into a scale, which I would agree is needed

[kevin]

If this was 100 kt at landfall then Rita would be what 80 kt? Katrina kept the eye all the way up to landfall and was not weakening rapidly. I don't see how it could be 100 kt. Portions of interior Mississippi were heavily damaged as well, and if Katrina was 100 kt at Louisiana then it would drop down to 60-70 kt by the time it was well inland. And that wasn't the case. If Katrina was 100 kt in Louisiana it would be 90 kt max at the MS coast.

I think measuring wind speed on damage is a really dumb way of doing things. After all structures will fair differently based on their composition, angle of wind, gusts et cetera. Also trees will fair differently on those same variables and also the amount of rainfall and the type/age of the tree.

You know how you measure windspeed? By recording wind speed!

[Scorpion]

Wasn't there reports of 124 mph winds on the MS coast?

[Derek Ortt]

yeah

a gust, just like the 119KT gust recorded by Sudduth here. But that is not sustained wind

[curtadams]

It's possible, though, that the gusts do the damage, and not sustained speed. The normal response of a structure, after all, is to be able to withstand forces up to a certain level indefinitely and collapse at forces only slightly higher. Tornados, after all, do tremendous damage and it's an exceptional tornado that delivers a high wind for an entire minute. Gust-caused damage would help explain the notorious variability of hurricane damage.

[manofsteele79]

I don't care what their analysis said..... I live 70 miles inland (Hattiesburg, MS) and it looked like a bomb went off. Trees down everywhere (not isolated), roofs gone, houses and cars crushed.... it was a disaster. My parents live 15 miles inland in Baldwin County Alabama and our damage was worse than their Ivan damage last year.

[Scorpion]

It would be rapidly weakening if it was 100 kt at landfall, and that wasnt the case. I see no satellite signature of RAPID weakening like Rita or Ivan. The winds would probably be of TS force if it was rapidly weakening in Mississippi, and that wasnt the case.

[Matt-hurricanewatcher]

What I seen at landfall was the western side of the storm rewraping...Also the EWRC that had happen. Had ended which it made second landfall with one eye.

[jasons2k]

It would be rapidly weakening if it was 100 kt at landfall, and that wasnt the case. I see no satellite signature of RAPID weakening like Rita or Ivan. The winds would probably be of TS force if it was rapidly weakening in Mississippi, and that wasnt the case.

Storms don't weaken in a "straight line". A storm will weaken from 110kt to 80kt much faster than it will from 80kt to 40kt.

[Derek Ortt]

it could still be rapidly weakening and still have caused extreme winds in MS inland

Those may have been gusts, not sustained, as the winds aloft were 134KT at landfall, at the 700mb level. I would need the vertical velocities to determine if it is convective or stratiform, which would help determine the reduction factor. The dropsonde surface winds seem to indicate a stratiform storm, which means in isolated convective regions, extreme gustsare likely since the winds aloft would be transported briefly to the surface

If this is determined to have been a 3, this would show us that 2 cat 3's of 100KT are not the same and probably should not be compared to each other, unless the dynamics themselves match

[jasons2k]

Deleted (it was in response to "greatone's" email)

[Derek Ortt]

to get back on track

there are dropsondes which also tend to support the low-end category 3 status as well. Air force sondes are higher, which means testing needs to be done 9AF sondes also typically failed at slightly higher altitudes than did NOAA ones)

We do need to accurately determine the intensity of Katrina so that we can make plans for the future as to how far inland needs to be evacuated for a category 3 hurricane, which is why I am really interested in the final results, which I will ccept, unless new data suggests otherwise

[kevin]

Yeah it has to be great one.

[cycloneye]

Inactivated.

[HurryKane]

Inactivated.

While you're at it, can you remove the private emails he posted? Thanks