Do N moving hurricanes in the N GOM naturally weaken?

[BayouVenteux]

Mobile...They're talking about the proposed liquified natural gas terminals that the major petrochem companies want to build off the La. coast.

Check it out:

http://2theadvocate.com/stories/052205/ ... s001.shtml

[mobilebay]

Mobile...They're talking about the proposed liquified natural gas terminals that the major petrochem companies want to build off the La. coast.

Check it out:

http://2theadvocate.com/stories/052205/ ... s001.shtml

Oh. I was as lost as a blind dog in a meat house!

[tallywx]

The northern motion and "dry" air did not weaken Frederic in 1979. And that was a VERY broad Storm. So that point is mute.

Not any broader than average. Probably average size in area.



For a storm due south of Mobile, the CDO shield extends about to south of Destin.

Compare that to Hurricane Opal, which when it was due south of Mobile had a CDO that extended all the way south of Tallahassee. That's twice as large.

http://www1.ncdc.noaa.gov/pub/data/imag ... e-opal.gif

[mobilebay]

Are we looking at the same Image. My goodness, that thing is huge. That is a huge CDO!

[HurricaneBill]

Super Typhoon Tips looked sick to that is a point people need to learn that a powerful hurricane doe's not always have a clear eye.

Have you seen a pic of Super Typhoon Tip at peak intensity? He looked anything BUT sick.


http://vos.noaa.gov/MWL/aug1998.pdf

[AussieMark]

Anyone seen a image of Hurricane Luis at peak intensity?

I haven't thats all was wondering what Luis looked like

[Hyperstorm]

Hurricane Luis.....One of the largest and MOST impressive hurricanes I've EVER seen...I remember it very well as it was moving VERY rapidly directly toward the islands of the Caribbean. I remember thinking that it would have been even more of a Catastrophe if it had followed its forecasted track toward Puerto Rico and Hispaniola...



At the time of this image, it was a low-end Category 4 hurricane. Ironically, its peak intensity (pressure) occured a few days after this picture, but its satellite signature wasn't as good as it is shown here...

[HurricaneBill]

Does anyone think Luis's peak winds were slightly underestimated?

His peak winds were 140 mph. Personally, I think 145 mph sounds more likely. Especially when Luis was an annular hurricane.

[Brent]

Opal was HUGE... clouds from it were ALL THE WAY UP the Eastern Seaboard! and that was 12 hours before landfall(250 miles offshore since it was FLYING).

[tallywx]

Opal was HUGE... clouds from it were ALL THE WAY UP the Eastern Seaboard! and that was 12 hours before landfall(250 miles offshore since it was FLYING).

Didn't at one point (perhaps at landfall), tropical storm force winds extend out 300 miles from the center?

I know that with a landfall at Pensacola Beach, Florida State University's meterology building in Tallahassee was gusting to 62 mph, sustained around 45. And that's 200 miles away from the center! St. George Island causeway, a good 150 miles from the center, was reporting sustained winds of 73 mph. Basically hurricane force! Amazing stuff.

[EDIT: Here's a play-by-play account of Hurricane Opal and the trials and tribulations of the mets. at the FSU met. department during the event. This was authored by Jon Rizzo, who now is WCM at the NWS Office in Key West.

http://tfn.net/~path/opal.txt
]

[Opal storm]

Lili was sheared like a chea-pet, as has been documented many times.

It was also the most disorganized cat 4 hurricane, EVER. Recon radar showed only about a 50% eye wall at peak intensity and hurricane force winds did not even extend to the SW quadrant

What was Opal's eye like?

(Yes, Opal did have an eye.)

THAT was almost a 5? That looks SICK.

Charley was almost a 5 at landfall,but on some images it barely looks worth a category 1.Can't judge the storm by the way it looks.

[Matt-hurricanewatcher]

A pic of Charley

http://www.osei.noaa.gov/Events/Tropica ... 26_G12.jpg

[Matt-hurricanewatcher]

The radar of Amazing Charley. Nice cirle of death.


http://www.nhc.noaa.gov/prelims/2004charley4.jpg

[Huckster]

Here's something I posted way back last year about north Gulf major hurricanes:

Andrew weakened 2 full categories over Florida.

Also, it weakened from 125KT to 100KT in the final 6-12 hours prior to its landfall along the Gulf Coast, which is actually quite typical of major hurricanes in the northern Gulf

To say that something is typical is to say that it is representative or characteristic of the group, family, setting, etc., of which it is a part. If significant weakening just before landfall is typical of major hurricanes landfalling in the northern Gulf Coast, then, it would seem, a majority of major hurricanes in that region would have to weaken significantly just before landfall.

In my opinion, there is only one practical way of looking at this. That one way is this, to look at every hurricane which made landfall in the northern Gulf of Mexico, which also was at major hurricane status 6-12 hours before landfall. By "northern Gulf Coast" or "northern Gulf of Mexico" let that be understood to be coast from Brownsville, Texas to Tampa, Florida.

I cannot give precise times of landfalls, so I will give the wind speed at what appears to be the first coordinate inland and the three coordinates preceding it. That would be inland, then six hours, then twelve hours, then eighteen hours before. Also, I am only using information which is included in the re-analysis, which only goes to 1910 so far. The reason is because there appear to be serious discrepancies in the data after that. For example, and this is the only purely Gulf storm for which I've seen the revised track data, the LA hurricane of 1926 was listed as a Cat. 2 at landfall, but it is now listed as a Cat. 3. I suspect there will be many other such changes, both up and down, but I don't think that will somehow completely overturn the nearly 60 years of evidence before it. Here we go:

H. #4, 8/23/1851 FL 90kt 100kt 100kt 100kt
H. #1, 8/26/1852 MS/AL 90kt 100kt 100kt 100kt
H. #5, 9/16/1855 LA/MS 100kt 110kt 110kt 100kt
H. #1, 8/10/1856 LA 110kt 130kt 130kt 120kt
H. #5, 8/31/1856 FL 90kt 90kt 100kt 100kt
H. #1, 8/11/1860 LA/MS 100kt 110kt 110kt 100kt
H. #3, 9/16/1875 TX 90kt 100kt 100kt 90kt
H. #4, 10/03/1877 FL 90kt 100kt 90kt 90kt
H. #4, 9/01/1879 LA 90kt 110kt 110kt 110kt
H. #2, 8/13/1880 TX 110kt 130kt 120kt 110kt
H. #2, 9/10/1882 FL 80kt 100kt 80kt 80kt
H. #5, 8/20/1886 TX 85kt 135kt 130kt 120kt
H. #10, 10/12/1886 LA 75kt 105kt 105kt 105kt
H. #10, 10/02/1893 LA 95kt 115kt 115kt 105kt
H. #5, 10/09/1894 FL 85kt 105kt 105kt 105kt
H. #4, 9/29/1896 FL 85kt 100kt 110kt 110kt
H. #1, 9/09/1900 TX 90kt 125kt 125kt 125kt
H. #6, 9/26/1906 MS/AL 65kt 95kt 95kt 100kt
H. #4, 7/21/1909 TX 90kt 100kt 90kt 80kt
H. #8, 9/21/1909 LA 105kt 105kt 105kt 105kt

I may have mistyped something, misread something, or just got it completely wrong, but I think most of these numbers are accurate. Now, I know these numbers are all estimates, and that means they might not be 100% right. However, I think there is a enough of a consensus to show that the majority of these storms did not drastically, amazingly, incredibly, or, miraculously weaken. That would mean that it is not typical for north Gulf major hurricanes to weaken 15 or 25 or even more knots right before landfall, at least based on this information.

Again, for storms after 1910, there are a lot of problems still. Nevertheless, let me give some guesses on some more recent storms.

2004, Ivan: how much did it weaken? I think that's probably the storm that really got all this intensity stuff going in the first place. Who knows, yet.
2002, Lili: if your faith is based on north Gulf storms falling apart right before landfall, then Lili would probably be either your patron saint or maybe your god. Even amongst weakening storms, Lili is not typical though. Few storms have weakened quite that quickly in the north Gulf.
1999, Bret: From 120kt to 100kt is rather dramatic. Dry air?
1995, Opal: 130kt to 100 is pretty signicant weakening. Shear and cooler water?
1992, Andrew: Andrew weakened a good bit, no doubt. Dry air I believe.
1985, Kate and Elena: Kate weakened quite a bit, but before jumping to conclusions, keep in mind that comparing a late November major hurricane to storms mostly from August to early October is not very reasonable. I don't know how much if any Elena weakened before hitting Mississippi, but I know it was not tremendous or anything. Certainly not Lili-esque.
1983, Alicia: No weakening I know of.
1980, Allen: Definite weakening, dry air I think, and slowing down.
1979, Frederic: A good example of a storm at least holding its own, no dramatic weakening.
1975, Eloise: No weakening.
1974, Carmen: Definite weakening. I have not found very much info about this storm, so I don't know what caused the weakening, but its track is kinda goofy looking. Looks like it slowed down as it neared the coast, so maybe dry air?
1970, Celia: No weakening.
1969, Camille: No weakening much if any.
1967, Beulah: Not sure, looks to have weakened and possibly have slowed.
1965, Betsy: Definitely doesn't seem to have been weakening at landfall. It took a very long time (relative to hurricanes) for it to start to fall apart after landfall.
1964, Hilda: Definite weakening, I think from 130kt to 105kt at landfall. That's pretty big. Storm definitely slowed down a lot right ahead of a coldfront, and I would bet this storm got sheared pretty badly near landfall and after.
1961, Carla: No weakening, as far as I can tell. If it was weakening, I cannot imagine how bad it would have been if it was strengthening.
1957, Audrey: Audrey was not weakening at all. In fact, it seems to have been strengthening and accelerating.

So that is 19 storms since 1950 that were majors right before landfall. Of those, about 8 hurricanes seem to have weakened significantly, (15kt or more is my guess). That's about 42% of storms. If we take out a couple of crazy storms, Audrey and Kate, that puts it at 7 out of 18 storms, or about 39%. Assuming this isn't all voodoo and snake oil, it would be hard to say that it is typical of north Gulf storms to weaken like Andrew did (25kt), much less like Lili. Of course, there are likely to be changes in all this data in years to come as it is reanalysed. This also makes me think that in that first batch of storms I mentioned, 1851-1910, some of those storms probably weakened more dramatically than is indicated, but most of them did not apparently try to commit suicide like a couple of more recent storms. My opinion is this, a not insignificant minority of the storms weakened significantly before landfall, with the majority roughly staying steady (slightly weakening/slightly strengthening).

I think the best way to look at this is to say it is typical of northern Gulf hurricanes to behave according to their environment. Storms which are slowing will tend to pull in dry air. Storms in the late season tend to be affected by shear and cooler waters or both. Allen, Andrew, Bret, and Carmen slowed and pulled in dry air most likely. Hilda, Kate and Opal were victims of fall weather patterns and cooler water. Lili was destroyed by Dynomat and Pat Robertson. The rest of the storms seem to have maintained themselves fairly well. I guess you could say it's not extremely uncommon for major Gulf storms to weaken a lot, but you'd still have to say most simply do not weaken all that much.

Comments and questions welcome.

[george_r_1961]

Whether or not a storm pulls in dry continental air before landfall also largely depends on the expanse of the circulation and its forward speed..as well as the angle from which it approaches the coast. A fast moving, tightly wrapped storm approaching Mississippi on a due northerly course would have little weakening before landfall. A slow moving larger storm paralelling land before landfall would get more dry air entrainment; this is why a lot of storms approaching the Carolinas after dawdling offshore have less convection on the west side of the storm than would be expected. These two examples assume that all other factors such as shear and SST's remain favorable and constant.

[PTrackerLA]

Lili weakened because of all of us catholics around here praying all night long . Maybe not entirely true but that storm had me totally freaked out. It was forecast to come right up the gut (vermilion bay) into Lafayette bringing SUSTAINED winds of 135mph into the city. The damage would have been catastrophic being that the 85mph winds brought the city to its knees for days.

[Dave C]

I thought Pat Robertson only affected hurricanes approaching Mid-Atlantic(near where he lives) LOL. Nice recap Huckster, Another point about Gulf systems, I remember Alberto which had been suffering from shear but as it moved into the northern gulf the upper environment improved allowing it to intensify the last few hrs. before landfall. Although it wasn't a hurricane at landfall(65mph I think) An eyewall was reportedly forming but landfall halted intensification. Hurricane Erin in 95 or 96 intensified at landfall on the Florida panhandle. Was one of the best looking 85 mph storms I've ever seen, Pressure was 974 mb at landfall having dropped about 10mb the last several hrs before landfall.