Katrina H-Wind Analysis, marginal 3 at landfall

[NorthGaWeather]

You would an an OKay forum forecaster if you wouldn't spend so much time knocking everyones posts you don't agree with.

Well said.

[Aslkahuna]

In essence, what you are seeing is chaos in action where minor changes in the storm environment including changes caused by the storm because of feedback cause changes in the strom's structure and intensity. Sometimes these changes will reflect more in the wind field than in pressure and there's something else we have to remember-the release of energy in a storm is NOT just reflected in wind but also in the intensity of rainfall. There could be big intense storms that are 60-70% rain and 30-40% wind (as the forecasters in PAGASA would put it when I was in the Philippines) and sometimes the other way around. I suspect, though I can't prove it since the supporting data is probably not available and I'm not a research Met, that Tropical Cyclones are at their windiest when they are in a rapid intensification phase and just before to at their peak and then they tend to expand and begin their wind down-we see this in other cyclonic systems like tornadoes and ET lows so why should a TC be any different? Also, there's a latitude factor involving the total spin of the system which is conservative in a steady state storm. As a storm gains latitude, the winds should lessen since although the total spin of the storm remains the same (all other factors being equal and ignoring friction from the sea surface for the time being), the contribution to that spin from Earths rotation will increase as a function of the sine of the latitude which is not a linear function.

Steve

[SacrydDreamz]

Carla probably was legitimatly a 4. I would have to look at the flight level data, with the vertical velocities

again, had my Rita experience not have happened, I would have thought the idea was downright laughable. What is needed is numericla modeling studies to determine WHEN and WHY some storms like Rita can be 911mb cat 3's, after being 897mb cat 5's

I think this is absolutely ludicrous.

[SacrydDreamz]

In essence, what you are seeing is chaos in action where minor changes in the storm environment including changes caused by the storm because of feedback cause changes in the strom's structure and intensity. Sometimes these changes will reflect more in the wind field than in pressure and there's something else we have to remember-the release of energy in a storm is NOT just reflected in wind but also in the intensity of rainfall. There could be big intense storms that are 60-70% rain and 30-40% wind (as the forecasters in PAGASA would put it when I was in the Philippines) and sometimes the other way around. I suspect, though I can't prove it since the supporting data is probably not available and I'm not a research Met, that Tropical Cyclones are at their windiest when they are in a rapid intensification phase and just before to at their peak and then they tend to expand and begin their wind down-we see this in other cyclonic systems like tornadoes and ET lows so why should a TC be any different? Also, there's a latitude factor involving the total spin of the system which is conservative in a steady state storm. As a storm gains latitude, the winds should lessen since although the total spin of the storm remains the same (all other factors being equal and ignoring friction from the sea surface for the time being), the contribution to that spin from Earths rotation will increase as a function of the sine of the latitude which is not a linear function.

Steve

Interesting point regarding the rainfall... but a drop in pressue must correlate with an increase in wind to some degree, somewhere, assuming the environmental pressure field remains essentially unchanged. A 911mb cat 3 doesn't fly with me --

The latitudinal difference & thus difference in input from coriolis is insignificant within the confines of the Gulf of Mexico.

[SacrydDreamz]

andrew was a Cat 5 at 922 on the saffir simpson scale anywhere below 920 mb is CAT 5 now that begs the question was Andrew 150 MPH instead of 165MPH.A 922 MB Hurricane is between 150-155 strong CAT 4.Why was Andrew a CAT 5 with Cat 4 pressure i know the skater anology he had his arms tucked in blah blah blah but he had CAt 4 pressure which i'm trying to get at

920 mb is an arbitrary marker -- there is no essentially no difference between 919mb and 921mb.

[Derek Ortt]

very possible to have a 911mb cat 3 if the vertical velocities in the eye wall are only 4 m/s

it was a cat 4 aloft as flight level winds in Rita were above 130KT, but this was not being transported down to the surface.

SS, pimp JB all you like, doesnt change the fact that he has spread a falsehood

[Stormcenter]

I wish people would respect 'Profession Met' statements. I have a
Mechanical plus Civil Engineer degree which took 4 years plus 2 summer
schools(typical five year degree). So I took courses which are close to what the 'Mets' took.
The 3D fluid action of one storm can not be compared to another storm or A + B =C DOES NOT exist. Storms are like people, no two are the same. I have spent many hours reading posts but attack the 'Mets'
by given certain posters is new and out of line. As a ex-NCO in the Marines, I would never talk to someone who out rank me like what I have read of late.

<Eddie>

I don't think anyone is attacking "Pro Mets" but more so defending themselves from their attacks they deem necessary when they don't agree with an "Non-Pro Met's" post.

[Stormcenter]

very possible to have a 911mb cat 3 if the vertical velocities in the eye wall are only 4 m/s

it was a cat 4 aloft as flight level winds in Rita were above 130KT, but this was not being transported down to the surface.

SS, pimp JB all you like, doesnt change the fact that he has spread a falsehood

Such eloquent words spoken from a Pro Met, hmmmmmm.

[jazzfan1247]

Hello everyone. I often lurk and read through these boards, but never posted…but from what I’ve read in this thread I feel I have to post.

Quite a few people have made claims such as “the damage here is incredible…no way this was a cat 3” or “come and see for yourself the damage, there’s…just…no…way” and the like. The use of such “scientific” evidence over the objective, observed data that Derek has posted is quite alarming to say the least. Yes, damage can be used to estimate intensity, but there are many different factors that go into how significant the damage looks, such as how well the house is built, how long the strong winds lasted, etc. To take damage over wind data recorded by scientific instruments that have been tested over and over is ridiculous. And yes I know the SFMR has had its questions, but Derek said the dropsondes have recorded similar results, and has ANYONE questioned the validity of the dropsondes? Or how about the Doppler wind velocities?

Yes I realize it’s quite incredible to have a 911 mb storm as a cat 3, etc. but even Derek said he was amazed and didn’t expect it until he actually was on the flight into the storm. But he is willing to accept objective scientific data as it comes in, unlike quite a few here who rely on far less reliable evidence.

Now, the data analysis is not final, it’s a continuing process, but like Derek has stated, the data AT THIS TIME indicates that Katrina was a Cat 3 at both landfalls. The way so many here have completely dismissed this objective evidence presented really worries me.

And to those who believe “it doesn’t matter how strong Katrina was…she still did all that damage”…yes it is VERY important, because people need to know that they didn’t really survive a Cat X storm, so they won’t stay for the next one and get killed. And yes there should be more emphasis on the storm surge instead of top sustained winds, but how do we get there? We have to first PROVE that storms in the past (i.e. Katrina) had less winds, but still produced a monster surge. You can’t just tell people along the coastline that surge can still be Cat 5 without a Cat 5 storm, you have to have objective and scientific proof to back that up, so more people will be convinced and have no argument otherwise.

[SacrydDreamz]

Tell me, which is more likely... a 911mb cat 3 or recon not finding the higher winds?

You mention VV's, well 4 m/s is fairly normal for strong hurricanes, no? Chances are that the largest VV's and tangential velocities were not sampled...

[Derek Ortt]

the previous dat, the vertical velocities were 16 m/s and the highest has been about 22. 4 m/s is very small

Recon also flew 2.5 alpha patterns, so the entire stormw as well sampled

[dhweather]

For information about Andrew's intensity and "promotion" to Category 5 at landfall, be sure to read the HURDAT analysis:


http://www.aoml.noaa.gov/hrd/hurdat/andrew.html

I guess we get no re-analysis of Camille, as Katrina wiped out most everything.

[Scorpion]

I believed the maps a little bit, until I went back and saw they showed a 908 mb Cat 3 Katrina. What a joke.

[jazzfan1247]

I believed the maps a little bit, until I went back and saw they showed a 908 mb Cat 3 Katrina. What a joke.

A joke? Derek has presented his hard scientific evidence, where is yours? Look, it's perfectly fine to state your amazement of the fact that a 908 mb hurricane could've been a cat 3 (as I am myself), but to state that it's a joke without any objective evidence backing that up is ridiculous.

[Aslkahuna]

For a verified Cat 3 intensity storm, view the Typhoon Omar video by Jim Leonard. That storm was confirmed by actual wind measurements to be sustained 105kt (120 mph) over Guam and his video is from very close to where the strongest winds were measured (also notice that Jim is more conservative and likely more accurate in his wind estimates than his chase partner). The long form video from him (language rated R) is very informative as it clearly shows frequent lightning occurring during the afterwind portion of the storm in the early evening after eye passage. Omar was in a RIC when it passed over Guam and lightning was quite common in the storm.

Steve

[Dave C]

I have Jim's Omar footage too....good stuff. Have you seen his Katrina footage from Slidel? He estimated gusts up to 140 and that was on nw side of eyewall.

[Aslkahuna]

A peak gust of 140mph would imply a sustained wind of 115 mph (100kt) or Cat 3 winds at Slidell. I haven't seen any of his Katrina video yet.

Steve

[timNms]

Hello everyone. I often lurk and read through these boards, but never posted…but from what I’ve read in this thread I feel I have to post.

Quite a few people have made claims such as “the damage here is incredible…no way this was a cat 3” or “come and see for yourself the damage, there’s…just…no…way” and the like. The use of such “scientific” evidence over the objective, observed data that Derek has posted is quite alarming to say the least. Yes, damage can be used to estimate intensity, but there are many different factors that go into how significant the damage looks, such as how well the house is built, how long the strong winds lasted, etc. To take damage over wind data recorded by scientific instruments that have been tested over and over is ridiculous. And yes I know the SFMR has had its questions, but Derek said the dropsondes have recorded similar results, and has ANYONE questioned the validity of the dropsondes? Or how about the Doppler wind velocities?

Yes I realize it’s quite incredible to have a 911 mb storm as a cat 3, etc. but even Derek said he was amazed and didn’t expect it until he actually was on the flight into the storm. But he is willing to accept objective scientific data as it comes in, unlike quite a few here who rely on far less reliable evidence.

Now, the data analysis is not final, it’s a continuing process, but like Derek has stated, the data AT THIS TIME indicates that Katrina was a Cat 3 at both landfalls. The way so many here have completely dismissed this objective evidence presented really worries me.

And to those who believe “it doesn’t matter how strong Katrina was…she still did all that damage”…yes it is VERY important, because people need to know that they didn’t really survive a Cat X storm, so they won’t stay for the next one and get killed. And yes there should be more emphasis on the storm surge instead of top sustained winds, but how do we get there? We have to first PROVE that storms in the past (i.e. Katrina) had less winds, but still produced a monster surge. You can’t just tell people along the coastline that surge can still be Cat 5 without a Cat 5 storm, you have to have objective and scientific proof to back that up, so more people will be convinced and have no argument otherwise.

What are we to think when a retired AMS (who worked with NWS and NOAA) "Pro-met" was witnessing the destruction of his city first hand and he reports that winds in Waveland were sustained at 145 and the surge height was 40 feet? Do we dismiss his expertise? Or do we take the word of other pro-mets who have NOT been there to assess the damage first hand?

[jazzfan1247]

True, the other pro-mets weren't there at the scene, but they DO have access to objective data obtained by weather instruments that do not contain things such as human emotion, bias, etc. Even Derek said himself that he underestimated the winds when Katrina came through his area. Now, for all I know, your retired-met friend could be a perfect human being, capable of estimating sustained winds with an accuracy better than that of calibrated scientific instruments. But personally, I would go with the scientific instruments, and so should everyone else.

In the absence of other evidence, more weight would be put on such first-hand accounts as your retired-met friend, but the point is that we DO have better evidence, evidence that suggests that he overestimated the sustained winds, which from what I’ve read is really not very difficult to do. So yes, go ahead and ponder over his first-hand account, but be aware that less weight should be put on it compared to dropsonde data, radar data, etc.

Human observation can be a powerful tool, but there are certainly limits, and this is one of them. If we were so accurate, why don’t we use human observation to determine exact wind speeds at any given location? We don’t; we use weather instruments, quite simply because they are more accurate. The same principle applies here: the objective data is much more reliable than a biased, emotional observer who has observational limits as a human being.

And yes, I am aware of the Lake Charles station possibly underestimating the winds, but that is really quite rare. And in Katrina's case, we had not only SFMR, but also dropsondes and radar velocity...and multiple recon flights showing the same data. In my opinion, there's absolutely no way ALL of these underestimated the winds by a significant degree.

[Scorpion]

Recon supported Cat 4 at landfall.