Want to see some real Katrina data?

[Pearl River]

4.5 miles from HWY 90 along HWY 49 to I-10 in Gulfport.

[Audrey2Katrina]

137 mph wind gust...would probably equate to somewhere around 95-105 mph sustained using the overland gust ratio. This seems reasonable given the fact that this is assumably 5 or so miles inland, and the anemometer was shorter than the standard 10m height. This recording would probably indicate that strong Cat 2, weak Cat 3 conditions existed right along the beaches imo. Areas west of Gulfport may have gotten slightly higher sustained winds, but due to the broadness of the wind field, probably not much higher. These areas probably got higher gusts though judging from the convective blowups on radar which would've transferred higher gusts to the surface.

Seems to indicate to me, given all the data revealed plus the fact that there is no way to assume these are the highest and that they WERE well below the height that they should have been, that there's little doubt at all about Cat 3 ...right there at the site of the anemometer... less doubt along the beaches, and I agree, stronger closer in to the center. But all this is moot, I suppose as even the NHC has called it a 3 at landfall.

Did you watch the video?... quite impressive in the later goings.

A2K

[Audrey2Katrina]

Hurricane, just out of curiosity; do you have the time that the video began? Or the times on any of those readings. Once I had it buffered, I spotted around--didn't realize it was a 4 hour plus video, ... I found that pole on the concrete base swaying in the wind around 1:31 and again close to the 2:00 point times of fairly peak intensity. Things pretty much seem to calm down to blustery squalls after the 3 hour mark... once again, thanks for the watch!

A2K

[MGC]

Have to disagree with you there Jazzfan. Visual comparison of wind damage in west Harrison County and the Diamondhead area are conclusive that the futher west one goes towards landfall the greater the extent of wind damage. Yes, the wind field was broad but the area near eyewall landfall in the RFQ area had considerably greater wind damage than the Gulfport area.......MGC

[Margie]

137 mph wind gust...would probably equate to somewhere around 95-105 mph sustained using the overland gust ratio. This seems reasonable given the fact that this is assumably 5 or so miles inland, and the anemometer was shorter than the standard 10m height. This recording would probably indicate that strong Cat 2, weak Cat 3 conditions existed right along the beaches imo. Areas west of Gulfport may have gotten slightly higher sustained winds, but due to the broadness of the wind field, probably not much higher. These areas probably got higher gusts though judging from the convective blowups on radar which would've transferred higher gusts to the surface.

No and no.

The weakened wind gradient not only reduces the sustained winds, but increases the ratio between sustained wind and wind gust, and air funneled between buildings increases the speed of wind gusts (Bernoulli effect).

Remember, videos of winds in downtown Gulfport which were less than a mile from the beach do not show Cat 2 or 3 winds.

[jazzfan1247]

Have to disagree with you there Jazzfan. Visual comparison of wind damage in west Harrison County and the Diamondhead area are conclusive that the futher west one goes towards landfall the greater the extent of wind damage. Yes, the wind field was broad but the area near eyewall landfall in the RFQ area had considerably greater wind damage than the Gulfport area.......MGC

That's why I said I thought the gusts were higher, and the gust ratio was higher. I suspect that the sustained winds in those areas probably weren't any more than 5-10 mph greater than say Gulfport, but the gusts were probably higher than they "should" have been for such a small difference in sustained winds. That's just what I think...

[jazzfan1247]

No and no.

The weakened wind gradient not only reduces the sustained winds, but increases the ratio between sustained wind and wind gust, and air funneled between buildings increases the speed of wind gusts (Bernoulli effect).

Remember, videos of winds in downtown Gulfport which were less than a mile from the beach do not show Cat 2 or 3 winds.

I would like to see more info about this weakened wind gradient resulting in higher gust-to-sustained wind ratio. I have often wondered (other than land interaction) what influences this ratio to be higher or lower for each given storm, or for specific locations.

As far as the funneling effect goes, I'm trusting the chaser crew that they went to a specific location to minimize this effect and measure the "true" wind speeds. And about the videos, well it's hard to say much of anything conclusively about the winds from those...

[Margie]

The ratio is higher because less of the sustained winds are being brought down to the surface, but the occasional gust from the boundary layer rolls still makes it to the surface.

The funnelling effect always occurs unless the anemometer is in a very open area, such as an airfield, well away from trees, houses, buildings, etc.

[Audrey2Katrina]

Here is an interesting pdf from the testimony of Dr. Keith G. Blackwell, Coastal Weather Research Center, from the University of South Alabama.

http://commerce.senate.gov/pdf/blackwell.pdf

I find his comments on the needed upgrade of the SS scale interesting, and particularly liked his comments in the section: "Much more storm intensity research needed."

It addresses a lot of the issues/comments being bandied about in here including all the theoretical mumbo-jumbo about what this one or that one "thinks" about windspeeds and/or intensities.

There can be no doubt in any reasonable meteorologist's mind that Gulfport certainly received over Cat 1, and even Cat 2 sustained winds. The more intense the storm, the lower the original gust to sustained ratio has also been discussed in another article I've read. If I can find it again I'll post it here; but there is absolutely no doubt whatsoever in my mind.

A2K

[Stratosphere747]

The problem in reality is that there just have not been enough land falling storms of major intensity *3* or higher to study. There is a reason why they are a rarity and the damage is so severe. But without enough actual data to draw upon, it will continue to make true scientific opinions hard to be made.

What should be changed and we have debated this here for a few years before Katrina is the SS scale and the need for it to be changed, especially in the area of storm surge. Again though without enough data to actually study, there will be something of a grey area. I've just not had enough experience with the Slosh models out there to conclude how reliable they are.