Very Interesting Katrina Wind Map

[Huckster]

I'm not sure how these gust speeds were obtained, but the information on this map seems to conform well to the reports I've heard so far. It also could confirm Derek's assertion that Katrina was a cat. 3 at landfall in Louisiana, as a cat. 4 (based on a minimum of 131 mph sustained winds) would easily produce wind gusts much higher than the 150's mph. Over water, a 131 mph hurricane would probably produce wind gusts to at least 160 mph. Over land, the desparity would be greater. However, if this map is correct, then the possibility still exists that those kind of winds did occur; even though Katrina was large, I assume it's possible if not likely that in spite of the large area of wind gusts between 135-155 mph that some tiny spot right along the coast did get true cat. 4 winds. Yes, I know there's already a thread about Katrina's winds, but I thought this was especially important, and considering that thread's rapid and current growth, I want to make sure everyone has a chance to see this before it gets buried.

Beware, PDF...

http://www.hostunlim.com/msforestry/LoveImagery2.pdf

[Recurve]

This would be important -- if it had information about the agency that created it and the source of the "data." The company name on the first page doesn't really explain the authority or source. You said you don't know where the data is from.

Looks credible, but who knows, it's has no attribution. Anything else you know about it?

[wxmann_91]

Question: What is the reduction factor from gusts to sustained wind? Is it 70%, cause that's what I was thinking.

Another one: Are these gusts recorded or estimated?

[thunderchief]

I dont trust that map for a second. The winds are all wrong... theres no right side bias for the strongest winds. The gusts in mobile bay were stronger than that, as were the gusts in biloxi(a chaser near there picked up 130 or so).

EDIT: Besides, we know most of the instruments in the region of strongest winds lost power or were destroyed.

[Valkhorn]

I actually believe this map. I do know in Meridian, the only station to go through the whole thing did record a 90mph gust. I also know that in this situation there is still a slight eastern bias.

I wouldn't be surprised that some of our gusts in Hattiesburg were 130mph or so. The damage and what I saw with my own two eyes would agree with this map.

Seems like its pretty accurate to me - remember they are talking about gusts and not sustained wind speeds.

I would like to see their sources though.

[wxman57]

Question: What is the reduction factor from gusts to sustained wind? Is it 70%, cause that's what I was thinking.

Another one: Are these gusts recorded or estimated?

This map could use the HRD shape file of recorded Katrina winds. It's available for download on the HRD web site.

As for the reduction factor for gusts, there's a very large degree of variance. Typically, the factor is about 22% over water. But over land, the gusts could be as much as twice the sustained 1 minute wind. Remember, in Lili, sustained winds across south-central Louisiana were recorded at around 45-50 mph but gusts were 100 mph.

And there is definitely a "right side bias" on the gusts. Gusts are about 20 mph higher in the right eyewall than the left (126 over New Orleans vs. 145 in right eyewall). Wind gusts in Biloxi look fine, as they were likely in Cat 2 sustained winds. As for Mobile Bay, hurricane-force winds just didn't extend very far inland into Alabama. Surface friction kept those winds confined to the Bay.

[Ixolib]

Interesting map - and while not very detailed, certainly seems plausible to me. I stayed here for Katrina in Biloxi and believed throughout the storm, even at its peak, that the winds never reached a level that I was expecting. I've been through several other storms where the wind seemed significantly stronger in this neighborhood than what I experienced with Katrina.

Or, perhaps, the fact that the surge quickly became an issue for me and mine, I just simply did not pay as much attention to the wind in those peak times as I otherwise would have... Interesting how one's perspective on things can change in a moment or two.

Also, because my attention was diverted elsewhere than the radio, an added factor may be that I was not aware the storm was weakening on its third landfall, and consequently had higher expectations for the wind speed than what presented itself.

All-in-all, I can agree with the ~115 in and around coastal Biloxi.

[Steve]

Katrina is one of those storms that provides an obvious example of why the Saffir-Simpson scale is not really up to date. I don't know how else to classify storms, but the damage from Katrina, regardless of whether it was a 3 or 4, will likely exceed the damage from all previous Cat 5 storms combined. There's just no comparison. And to just say it was a Cat 3/IH doesn't do any justice to the over 1,000,000 people who were displaced as well as the hundreds of thousands of homeless people like me who have had their families split to the 4 winds or had their lives completely uprooted.

Steve

[Wpwxguy]

I think the map is probably what wxman eluded to. I think its some sort of estimation. I am just to the west of Bogalusa on that map and we did have 120 mph gusts. The map looks to be about right, but I was not on that east side near Biloxi so its all speculation by me.

[wxman57]

Actually, it looks like the map used EarthSat data.

http://www.forestone.com/fo_root/index.cfm

Not sure how they would use satellite to estimate surface winds, though, if that's what they used.

[Agua]

I do note that the map improperly depicts the locations of Biloxi (Jackson County?!?!?) and Gulfport (Eastern edge of Harrison?!?!?). But other than that, based on the damage sustained at my house in Ocean Springs ... (er, Biloxi? . ) that looks about right.

[otowntiger]

That is a very interesting map. I'd love to see one like it for Charley, Jeanne and Francis and other hurricanes. I doubt it is correct because officially there were a ton of stations that were knocked off line well before the height of the storm arrived. Maybe these are radar estimates?

I know for sure that it is not entirely correct because I've read a couple reports of 70+ mph winds in the western portions of Baton Rouge ( by a local news station) so it is possible to assume that higher winds occured on the east side of town.

[wxmann_91]

Question: What is the reduction factor from gusts to sustained wind? Is it 70%, cause that's what I was thinking.

Another one: Are these gusts recorded or estimated?

This map could use the HRD shape file of recorded Katrina winds. It's available for download on the HRD web site.

As for the reduction factor for gusts, there's a very large degree of variance. Typically, the factor is about 22% over water. But over land, the gusts could be as much as twice the sustained 1 minute wind. Remember, in Lili, sustained winds across south-central Louisiana were recorded at around 45-50 mph but gusts were 100 mph.

And there is definitely a "right side bias" on the gusts. Gusts are about 20 mph higher in the right eyewall than the left (126 over New Orleans vs. 145 in right eyewall). Wind gusts in Biloxi look fine, as they were likely in Cat 2 sustained winds. As for Mobile Bay, hurricane-force winds just didn't extend very far inland into Alabama. Surface friction kept those winds confined to the Bay.

Thanks for the info

[DESTRUCTION5]

Looks Like it has Cat 4 written all over it? 150's and 160's all over the friggin place...Who says Cat 3?

[terstorm1012]

Looks Like it has Cat 4 written all over it? 150's and 160's all over the friggin place...Who says Cat 3?

those are gusts, not sustained, if i understand correctly.

[weatherwoman]

bump for the info here very interesting info where do you guys get it?

[thunderchief]

The eye made landfall between slidell and bay st louis. It looks like he just projected winds, decreasing with time(inland) and space, equal on both sides of the hurricane.

That is not correct. The right side winds should be much stronger and further reaching than the left side... this clearly isnt the case here. Thus this is a poor estimation of peak gusts.

[Stormcenter]

The highest gusts reported in Mandeville, LA were 120mph. and downtown N.O. had a peak gusts of 114mph. So it sure seems accurate.

Great map!!!!!!!!!

[Weatherfreak14]

Great map. Looks accurate to me. Although what do I know.

[Scorpion]

Question: What is the reduction factor from gusts to sustained wind? Is it 70%, cause that's what I was thinking.

Another one: Are these gusts recorded or estimated?

This map could use the HRD shape file of recorded Katrina winds. It's available for download on the HRD web site.

As for the reduction factor for gusts, there's a very large degree of variance. Typically, the factor is about 22% over water. But over land, the gusts could be as much as twice the sustained 1 minute wind. Remember, in Lili, sustained winds across south-central Louisiana were recorded at around 45-50 mph but gusts were 100 mph.

And there is definitely a "right side bias" on the gusts. Gusts are about 20 mph higher in the right eyewall than the left (126 over New Orleans vs. 145 in right eyewall). Wind gusts in Biloxi look fine, as they were likely in Cat 2 sustained winds. As for Mobile Bay, hurricane-force winds just didn't extend very far inland into Alabama. Surface friction kept those winds confined to the Bay.

How were the winds in Biloxi only Cat 2 if Katrina was a 3 at landfall and had a very large area of Cat 3 winds?