Katrina H-Wind Analysis, marginal 3 at landfall

[senorpepr]

In Katrina (2005), landfall wind speeds at Grand Isle, Louisiana were approximately 140 mph with a central pressure of 920mb - the 3rd lowest on record for a landfalling Atlantic storm in the US. The above information is courtesy of the National Climatic Data Center (NCDC).

Derek, where did I ever say anything about me being on TV. You have so much room to talk with the way you just responded. I have always had respect for you until your statement just now. You are beginning to sound like Joe Bastardi with this wise information.

We are debating the obvious. That is what I am saying. NWS says above 140mph in Grand Isle. In the Western Portion of the eyewall, therefore the East Side is stronger. I don't think this storm was anything below 140mph. No debating a Cat 3. They say CAT 4!

No... that 140mph in Grand Isle was an estimate. The cat 3 debate is still viable.

[timNms]

Here's some "scientific" data for you to digest.

I posted this in this thread, but thought it should be reposted here.

http://www.storm2k.org/phpbb2/viewtopic ... 89#1090889

For those who are still skeptics, thought I'd relay this information to you.
I just spoke to an employee at Stennis Space Center. The unofficial report from Marine Government Science's instruments located close to the Pearl River in Hancock, County, MS (about 10 miles inland) shows sustained winds of 135 mph with gusts to 140 mph BEFORE the instuments failed. According to this employee, this occured BEFORE the eyewall reached that area.

I questioned why this was unofficial. I was told that until they can complete final analysis of the reports, it would be called "unofficial".

[TS Zack]

POPLARVILLE - PEARL RIVER COUNTY MS EOC
PEAK 117 KT

Thats a gusts to 135mph in Poplarville. I have no clue how many miles that is inland but it is certainly not near the coast. Just South of Hattiesburg. It is not the peak either, the station was then blown down.

[skysummit]

POPLARVILLE - PEARL RIVER COUNTY MS EOC
PEAK 117 KT

Thats a gusts to 135mph in Poplarville. I have no clue how many miles that is inland but it is certainly not near the coast. Just South of Hattiesburg.

Poplarville is 36 miles from inland from the coast.

[senorpepr]

Here's some "scientific" data for you to digest.

I posted this in this thread, but thought it should be reposted here.

http://www.storm2k.org/phpbb2/viewtopic ... 89#1090889

For those who are still skeptics, thought I'd relay this information to you.
I just spoke to an employee at Stennis Space Center. The unofficial report from Marine Government Science's instruments located close to the Pearl River in Hancock, County, MS (about 10 miles inland) shows sustained winds of 135 mph with gusts to 140 mph BEFORE the instuments failed. According to this employee, this occured BEFORE the eyewall reached that area.

I questioned why this was unofficial. I was told that until they can complete final analysis of the reports, it would be called "unofficial".

The equipment used at that location tends to read high during high wind/high precip events. That is why it is considered unofficial. Research on that type of anemometer shows that data above 100kt tend to be 85-90% of what is displayed.

[jazzfan1247]

POPLARVILLE - PEARL RIVER COUNTY MS EOC
PEAK 117 KT

Thats a gusts to 135mph in Poplarville. I have no clue how many miles that is inland but it is certainly not near the coast. Just South of Hattiesburg. It is not the peak either, the station was then blown down.

Ok granted we don't know how high the readings would've gone up to if it hadn't failed. But just taking that reading at face value, it suggests probably Cat 2 sustained, which seems pretty reasonable for a Cat 3 given that it's 36 miles inland.

[timNms]

Here's some "scientific" data for you to digest.

I posted this in this thread, but thought it should be reposted here.

http://www.storm2k.org/phpbb2/viewtopic ... 89#1090889

For those who are still skeptics, thought I'd relay this information to you.
I just spoke to an employee at Stennis Space Center. The unofficial report from Marine Government Science's instruments located close to the Pearl River in Hancock, County, MS (about 10 miles inland) shows sustained winds of 135 mph with gusts to 140 mph BEFORE the instuments failed. According to this employee, this occured BEFORE the eyewall reached that area.

I questioned why this was unofficial. I was told that until they can complete final analysis of the reports, it would be called "unofficial".

The equipment used at that location tends to read high during high wind/high precip events. That is why it is considered unofficial. Research on that type of anemometer shows that data above 100kt tend to be 85-90% of what is displayed.

How'd I know there would be an excuse?

[senorpepr]

Here's some "scientific" data for you to digest.

I posted this in this thread, but thought it should be reposted here.

http://www.storm2k.org/phpbb2/viewtopic ... 89#1090889

For those who are still skeptics, thought I'd relay this information to you.
I just spoke to an employee at Stennis Space Center. The unofficial report from Marine Government Science's instruments located close to the Pearl River in Hancock, County, MS (about 10 miles inland) shows sustained winds of 135 mph with gusts to 140 mph BEFORE the instuments failed. According to this employee, this occured BEFORE the eyewall reached that area.

I questioned why this was unofficial. I was told that until they can complete final analysis of the reports, it would be called "unofficial".

The equipment used at that location tends to read high during high wind/high precip events. That is why it is considered unofficial. Research on that type of anemometer shows that data above 100kt tend to be 85-90% of what is displayed.

How'd I know there would be an excuse?

It's not an excuse, Tim. It's been a known problem for nearly a decade now. I'm not trying to say whether or not Katrina was a 3 or 4. I'm just saying why your report is considered unofficial. That is why it wasn't included in the H-wind analysis.

[HurricaneBill]

Zack,

my advice to you is not to so quickly dismiss the finding of others based upon science as stupid. You will not make your quest to enter the field any easier, regardless as to how many TV appearances you have had in New Orleans

Why? You've done it before, Derek.

[Aslkahuna]

If that's the same type of anemometer that gave that 236mph reading on Guam during Paka, it's readings are to be taken with a pound of salt. A gust of 140 mph seems awfully low for a sustained 135 mph wind-at the very least the gusts should be in the 160+ mph range. For an inland station, using the derived gust ratio from JTWC of 1.25 (overwater), a gust of 135mph gives a sustained wind of 108 mph. Using the estimated ratios of 1.4-1.6 for overland from JTWC gives sustained winds of 96 mph and 84 mph respectively (Reference FLEWEACEN JTWC Tech Note 74-1).
Basically, what I'm trying to point out here is that reports of GUSTS prove NOTHING either which way-it's the SUSTAINED winds that count and specifically the one minute average wind measured at a height of 10 meters. Anything else is worthless until coverted to that standard.

Steve

[TS Zack]

How strong do the winds need to be to drive tree branches into roofs?

[Derek Ortt]

I've been told before not to flat out dismiss findings of others without having the evidence to back it up. That is something that is just not done

About the high wind readings, are they hot wire anamometers. In Georges, there were reports of gusts to 172 m.p.h. from hot wire anamometers, which ere discounted afterwards. The heavy rainfall distorts their readings. IN Paka, one recorded a 205KT gust

[senorpepr]

How strong do the winds need to be to drive tree branches into roofs?

I'm not sure on the average speed to accomplish that, but I'm sure the type of tree, the structure and health of the tree, and the structure of the roof have to be accounted for.

[senorpepr]

According to information from the NSSL, the FMQ-13 hot-wire anemometer has a "speed accuracy in the 99-150 knot range[of] +/- 15% and no accuracy is listed for speeds above 150 knots."

Thereafter, wind tunnel tests have been performed and it's been noted that the speed accuracy listed above was true. Since then, all gov't agencies have been notified of the accuracy problem and even military venues have to add a remark concering the accuracy. These instruments are still in use because the equipment is still very accurate in day-to-day operation. Only during the rare times (>100kt) is it considerably off. Therefore, it does not warrent the cost to replace all of the instruments because the appropriate conversions can be done to get a "good" idea of the real wind speeds.

[Aslkahuna]

In the wind tunnel tests, did they add a simulated heavy rain? A 15% error at 140 mph means that the wind could be as low at 119 mph (Cat3) or as high as 161 mph (Cat5)-not quite good enough to settle the debate.
One other point, Katrina was NOT a 908mb storm at landfall but in the mid 920's.

Steve

[Scorpion]

There never seems to be correct wind readings in Cat 4's. Doesnt mean you can dismiss them as being 3's. Recon is the BEST tool for these readings. In Ivan they barely found 100 mph sustained winds yet Ivan was 120 at landfall. Same for Rita. I don't care what people say, Katrina was a Cat 4 in LA and a strong 3 in MS. I will discount the ridiculous HRD which showed Jeanne as stronger than Katrina.

[senorpepr]

In the wind tunnel tests, did they add a simulated heavy rain? A 15% error at 140 mph means that the wind could be as low at 119 mph (Cat3) or as high as 161 mph (Cat5)-not quite good enough to settle the debate.
One other point, Katrina was NOT a 908mb storm at landfall but in the mid 920's.

Steve

I'm not sure if they added precip during those tunnel tests. However, it was noted at one point or another that precip on a hot-wired anemometer caused the anemometer to read too high.

[senorpepr]

There never seems to be correct wind readings in Cat 4's. Doesnt mean you can dismiss them as being 3's. Recon is the BEST tool for these readings. In Ivan they barely found 100 mph sustained winds yet Ivan was 120 at landfall. Same for Rita. I don't care what people say, Katrina was a Cat 4 in LA and a strong 3 in MS. I will discount the ridiculous HRD which showed Jeanne as stronger than Katrina.

Uhh... did you see the data in the first point of this thread? That is the most reliable data out there... which involves a lot of recon and good anemometers.

[Scorpion]

The HRD gave Jeanne a mid-strong Cat 3 reading if I remember correctly. It would be absolutely ridiculous to thing Jeanne was stronger than Katrina.

[timNms]

In the wind tunnel tests, did they add a simulated heavy rain? A 15% error at 140 mph means that the wind could be as low at 119 mph (Cat3) or as high as 161 mph (Cat5)-not quite good enough to settle the debate.
One other point, Katrina was NOT a 908mb storm at landfall but in the mid 920's.

Steve

I'm not sure if they added precip during those tunnel tests. However, it was noted at one point or another that precip on a hot-wired anemometer caused the anemometer to read too high.

Thanks for the reply, senorpepr. Would be interested to find the answer to Steve's question.