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An extraordinary Cat 5 in Australian waters

By: Dr. Jeff Masters, 4:14 PM GMT on March 28, 2006

We've got a truly exceptional Category 5 tropical cyclone in the waters off of the Western Australia coast to discuss, so the continuation of my blog on whether the global number of Category 4 and 5 hurricanes are increasing will have to wait. Tropical Cyclone Glenda is a Category 5 storm on the Saffir-Simpson scale, with maximum sustained winds of 160 mph and a central pressure estimated at 898 mb by the U.S. Navy (910 mb by the Australian Bureau of Meteorology). A central pressure of 898 mb is the lowest pressure ever estimated for a Southern Hemisphere cyclone, at least that I could find record of. Reliable records go back to the 1980s. The lowest pressure ever estimated for a Southern Hemisphere cyclone was 900 mb, for Inigo of 2003 and Gwenda of 1998. Both were Category 4 cyclones on the Saffir-Simpson scale, and hit Western Australia in a location near where Glenda is expected to strike on Thursday. The lowest pressure measured at the surface in a Southern Hemisphere cyclone was 905 mb at North Rankin A gas platform during Cyclone Orson on 22-23 April 1989. Orson had 160 mph maximum sustatined winds at the time, making it a Category 5 storm.

Figure 1. Tropical Cyclone Glenda is moving southwest, parallel to the Australian coast. This visible light image courtesy of the U.S. Navy.

Two weeks after suffering an estimated $1 billion in damage from Cyclone Larry, Australia must brace for another strike from a major hurricane. The region of Western Australia likely to be threatened by Glenda is not heavily populated, but is home to many important mining, oil, and gas operations. Over 1,500 people were eveacuated earlier this year when Tropical Cyclone Clare battered the area with 70 mph winds. Oil and gas operations are already shutting down as Australia battens down again. Glenda is in a very favorable environment for continued intensification, with water temperatures averaging 30 C (86F) underneath, and very light wind shear. It is possible that later today Glenda will reach the highest winds ever recorded in the Southern Hemisphere, equalling the record of 150 knots (172 mph) estimated for Cyclone Daryl/Agnielle in November 1995. Increasing wind shear on Wednesday should act to weaken Glenda, but she is still expected to be a formidable Category 3 or higher storm at landfall (Category 5 on the Australian intensity scale, which goes by wind gust). Glenda is the sixth tropical cyclone this season for the Western Australia area. On average, five of these storms form during the season, which runs November through April.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Yikes! That's something to wake up to!
Thats a single pixel that is missing. You wouldnt be able to see the aircraft even if it was there.

As far as why the single pixel is missing, I dont know.
cyclone I hope that you are aware that the image is not the same size in inches on everyone's screen. Sometimes not even close. Better to use pixels.
This seems to be a trend - the most intense storm in the Atlantic (Wilma) last year and now the most intense storm in the Southern Hemisphere (which is half the globe)... What will we have next - the most intense storm in the world (likely in the West Pacific)?
that black pixel is a tunnel. You can see that it is effectively stopping the hurricane in it's local area. Now if we had alot more of them.
Nope, the black dot is the cold war era Russia weather control machines vortex control beam. Somebody's working out the kinks so they can go full bore for the upcoming Atlantic season. lol

I would like to know what the Joint Typhoon Warning Center is basing their statement that Glenda is cat 5 on. The Dorvak Intensity Estimates only support a cat 3, and Glenda doesn't really look like a classic cat 5, and its eye just all but vanished on satellite imagery! If it is a cat 5, then it is going through a reorganisation process right now.
Actually, the eye didn't vanish, it just completely clouded over, sorry.
here is a link to the current microwave image of Glenda. I think she is beginning an eye wall replacement cycle.
ok, I am going to test putting an image on a comment. I have never done this before, so I hope it works. It should be a satellite image of Glenda. Here we go:

If this worked, you can see that the eye has infact vanished.
darn, it didn't work. Would someone please tell me how to put an image on your comment?
14. F5

Have you seen this guy before?


Thats a story on Scott Stevens.

Here is his web site

Weather Wars
Lets try this again:

Hey it kind of worked. Could someone please help me with this?
I fixed it. You were linking to a web page, not an actual .jpg file. In general, you need a:

img src=

tag that points to a valid image, with the tag:


at the end of the URL.

Jeff Masters
??? I've noticed that there seems to be an increase of conspiracy theories of late. Could this be related to global warming?

I have observed over the last few years that fog seems to drift into our brains... Perhaps paranoia comes from a general rise in temperatures. Right - and the moon is made of green cheese!
I'm holding onto my day job.
So... is it 898, or 910?

Do they have hurricane hunters down there, ready to spring into action?
I wonder how the solar eclipse will effect global warming, we haven't had one in a while.
Levi32 - you asked why the JTWC says that Glenda is a Category 5 when Dvorak says that it is a Category 3 - it is probably because of the pinhole eye; Wilma never had a Dvorak T number higher than 6.5 because the eye was so small that satellite intensities were too low.
The pinhole eye is also one of the reasons why you can't see much of an eye.
Solar eclipses have no effect whatsoever on the Earth's climate because they last for no more than a few minutes at any one spot and the area of totality is very small.
Yeah michael, that may be it. But the eye is gone now. It is probably going through an EWRC.

Jeff, thanks for fixing my image.
I'd expect them to have some effect, Michael, but probably about as much as, say, a nuclear explosion. Not a ton.

The JTWC read the remarks on the T5.5 - that number is due to constraints, without it it's T7.0.

She's definetly going into an eyewall replacement, and fortunately the shear will probably shred some of that beautiful organization before landfall.
I asked this before: Does anybody know if all of the storms with pinhole eyes (Larry, Floyd, and Glenda in two weeks) recently are unusual?
Ok lets see if I have this picture thing down. This will be a MODIS image of Glenda from last night.

Yes! It worked!!!
I think your link doesn't work.
I don't know why.
What was the problem?
Thanks, Michael
I got it; I also resized because it is very big (I re-wrote the HTML code; there was some king of error in it).

To re-size, add width=xxx height=xxx after the URL, where xxx is a number (such as 1/2 of the original size).

It then looks like this, with less-than and greater-than signs instead of paretheses:

(img src="http://www.npmoc.navy.mil/jtwc/satshots/sh2006sair.jpg" width=498 height=429)
The T-numbers have been increased to 6.0, which corrsponds to a low-end Category 4:

28/1333 UTC 17.0S 119.9E T6.0/6.0 GLENDA -- South Indian Ocean
MichaelSTL..what exactly were you asking about pinhole eye hurricanes? If you're asking if it is a recent phenomenon, no. Since the beginning of vertical observation of tropical storms, the pinhole eye has been considered a sign of impending rapid intensification.
I know that there have always been hurricanes with pinhole eyes, but they seem very common now - there were two last year in the Atlantic (Wilma and Beta) and Gilbert is the only other one that I can think of in the Atlantic. Furthermore, there have been three storms with pinhole eys in the past two weeks. I was just wondering if this is unusual or not (don't forget - Katrina and Rita underwent rapid intensification, but neither had pinhole eyes; in fact, Rita approached Wilma in speed of intensification and intensity).
How small does an eye have to be in order for it to be considered a pinhole eye?
I am not sure, maybe less than 10 miles; I consider a pinhole eye to be one that is too small to clearly distingush on satellite; compare these images of Rita and Wilma:

(from Wikipedia)
Hurricane hunters talking about flying into Wilma's pinhole eye~ The "pinhole eye" is a clue (as an eye shrinks, the storm gets stronger, and an eye less than 5 miles wide is rare).

Pinhole < 5 Miles? The article was interesting.
I'd say the prevalence of pinholes recently is fairly unusual. Pinhole for me is < 5 miles or so, they're usually extraordinarily rare.
Glenda is no longer a Category 5 and is predicted to weaken until landfall:

WTXS31 PGTW 282100
281800Z --- NEAR 17.1S 119.4E
290600Z --- 18.2S 117.9E
291800Z --- 19.8S 116.9E
300600Z --- 21.2S 116.3E
301800Z --- 22.6S 116.2E
Eye collapsed. I'm not gonna go with weakening till landfall, though...should regain a little strength before then.
how high did the winds get?????!!!! and how low did the mb go????!!!! and how small did the eye ger ???!!!
Cyclone, pinhole eyes have nothing to do with SSTs. David I believe the eye got down to 4-5 nmi, pressure down to 898mb, and winds to 160mph.
I think she might undergo an EWRC and strengthen slightly and then weaken before landfall. My guess is a low end cat 3.

You need to prove at least these two things to us.

1. That the tunnels would not do more harm to the enviroment than good

2. That the tunnels would not kill off hundreds of species of fish, and other forms of sea life
Also, I agree that pinhole eyes are more frequent over warmer waters. I think that the biggest reason for this is that tropical systems in general are more common with warmer SST's.
that's not proof, cbuster...and now, i will explain to a brick wall why that's not proof.
buster, if you were serious about getting people to listen to you, serious about getting these things designed/tested/modeled, you wouldn't be on here all the time blathering on about them...not to mention blathering on about replacing the statue of liberty with a statue of jesus, cloud seeding, etc.
How do you know that all sea life around the tunnels is most comfortable in water temperatures between 68 and 72 degrees? Have you looked at the preferred water temperatures for all of the species that live in the ocean? What would happen to the species that require the water temperatures to warm to a certain temperature before breeding? What effect would the cooler temperatures have on the sea plants?

Is it possible that the areas where cold, and warm water meet could create turbulence in the ocean itself, which could produce extremely large waves, and what effect would this have on the coastline?

What would the effect be on storms other than hurricanes? Is it possible that it could make winter storms more frequent in areas along the Gulf Coast?
Cyclone - why are you spamming us with this? You're only making yourself more and more absurd, and getting nowhere. None of us could do anything with it, even if we were convinced. Go talk to someone who can, and if they tell you it's no good, shut it.
Cyclone Zoe in the south western Pacific Ocean (Dec 2002 to Jan 2003), allegedly had a central pressure of 879 mb, according to JTWC & Wikipedia:


awk, another pinhole eye! another Cat 5! they are at the peak of their hurricane season (the equivalent of September for us).
It seems to me that the pinholing phenomenon is most likely to occur when the lower-level circulation is strengthening but the capping anticyclone is either immature (Wilma) or compromised by shear (β). Once the CA catches up, the pinhole either becomes unstable and collapses or inflates to a normal size. Storms that start out with a robust CA usually will not pinhole (Katrina, Rita). Why the phenomenon would be more common with higher SSTs is not entirely clear to me. Does this make sense to anyone?
Glenda seems to be expanding slightly, and the wind shear is decreasing a little. She still might make a comeback before landfall. Could someone direct me to some wind shear forecasts for Australia?
An amazing phenominon,hurricanes truly are,interesting how it is a category 5 a rare thing down under as far as I know.

You need to prove at least these two things to us.

1. That the tunnels would not do more harm to the enviroment than good

2. That the tunnels would not kill off hundreds of species of fish, and other forms of sea life**

No, what he needs to do is shut the hell up about his freaking tunnels already. NOBODY CARES TO SEE THAT CRAP ON EVERY SINGLE FREAKING BLOG!!!! It's as old and tired as the person with the first reply posting FIRST.


See how lame it is?

My apologies to everyone else. I just get sick and tired of having to wade through that crap to get to the great weather information provided on here.

Everybody's got e-mail.
Buster, you have no proof at all. Everything you have provided is speculation. You seriously need to take this to some engineering undergrads so they can work on. Right now all you have is an idea that is not fleshed out at all. Let some people who really know what they're taling about look at the idea, because in reality, no one here can help you, or they choose not to.

I understand your frustration. I am sorry for my part in continuing this argument, and very sorry that it makes it difficult for others who have no part in the argument to find the information that they are seeking. In all fairness, it is not just cyclonebuster who is responsible for the "crap". It is also the fault of all (myself included) who continue to try to disprove his theory.

In order to make this site more enjoyable, everyone needs to stop trying to prove him wrong. He is never going to stop arguing that his idea will work. I personally am finished with arguing about these tunnels, and advise everyone else to quit arguing as well.
For some reason, I think you're full of crap or else that would be your main argument for why it works. You havent taken it to any engineers, one that happened to run apon your idea on another web board ran it through a industry standard model and said that it didnt work, so dont say you have taken it to engineers and they said it worked. If you had you wouldnt be here, you'd be working with somebody getting it built for further testing.
Dude, until most nuclear bombs are disarmed, and there arent 10's of thousands of them waiting to be launched, global warming is not the biggest threat to our survival as a species.

If fact, global warming is a bigger threat to civilization then it is to our survival as a species. We lose all the knowledge we have gained over the last 2000 years, but there will still be groups of humans that return to thier hunter/gatherer origins. Hell, we survived ice ages, I think we'll survive a warmer planet.
You mean the people who said your idea could only possibly work for the gulf stream off the coast of Miami?
83. Inyo
as i biologist, i can tell you that 'most' sea life does NOT prefer temperatures of 68-72, and it would probably kill coral reefs to cool the water to that temperature all summer... coral reefs reduce the impact of storm surge and waves.

There are different types of sea life associated with different types of water. When El Nino occurs in southern California, different fish are found in the water than when La Nina or neutral conditions occur. Fish and some other forms of aquatic organisms can follow changes in temperature caused by climate or season, to stay in their optimal area. However, if an 'island' of cold water is created surrounded by warm water, the fish there will leave and the cold-loving fish from the north won't know to cross the 80 degree water to get there.
Cyclonenutjob, don't tell me what I can or can't tell you. {{sticking out tongue}} It's hard not to read your crap when you do nothing but spam this place with it. And don't worry about the big bad wolf blowing my house down. Nobody, including you, especialy you, and your damn tunnels are going to stop it if it happens.

Man, if only we could use the tunnel to get rid of you.....

How long have you been spouting off about this crap? Who exactly is it here that you're trying to convince? And how exactly is convincing that person going to change ANYTHING??

Get a freaking clue already. All this time you've WASTED blowing off about tunnels and you haven't changed a damn thing. What a waste.

Give it a rest.
I wonder how many of your posts I have to flag as spam before you are kicked off?
Nuclear winter is not possible to survive. Enough bombs would spread radiation throughout the entire planet, killing almost everything, expecially large, complex creature like humans.

The Earth is not going to become like Venus anytime soon, as the major reason it is so hot is that it is so much closer to the Sun then the Earth.
And don't forget that the concentration of CO2 was 20 times higher in the past and Earth definently did not fry.
Ahh, I'm not sure what that had to do w/anything, but yeah...

Anyways, returning to Glenda -

Australia will be very lucky if Glenda does not complete this ERC before landfall. If it can form a well defined eye before coming ashore then thier is always the possibility of restregthening right before and during landfall.
How strong is Glenda right now?
It's estimated by JTWC that Glenda is 922mb and 120 kt winds.
ERC is nearly complete, she'll have 1 more diurnal max as she approaches landfall...I smell a Katrina.

Does Anyone know how small the eye was when it was the Smallest....
i got a ? if this storm had 898mb and 160mph winds and i do not think a 898mb can have 160 so try more like 175mph or 180mph for 898mb

did the R storm have a 895mb and 180mph winds

so why dos this storm we are talking about have 160mph winds and a 898mb?

is any one geting me her
Cloud seeding has about as much proof as the tunnels, as in nothing but speculation.

I too smell a Katrina, and it kinda scares me. Katrina strengthen right out of her ERC into the Cat 5 beast she became. It would be the most rediculous thing to see a single storm to develope both a pinhole eye with 160 mph, and then an annular type eye with 160 mph...just crazy.
Wilma came close to doing that (185 mph with a pinhole eye and 150 mph with a Katrina-size eye).

The reason the winds are not higher is because this is not in the Atlantic. Other ocean basins have a much lower natural sea pressure, so it requires a storm to get much lower pressures then we see in the Atlantic to get winds that are as strong. I hope that explains it for you.

I would guess the eye was <5 miles across. It was probably closer to 2-4 miles across. It was very close to as small as Wilma was. Its very possible, in my view, that Glenda's eye became as small as Wilma's during her intesification.
that is still one nasty hurricane, hope they've got things tied down "Down Under"
Well From reading Jeff's Blog, This is what I get..... for some Fast Statistics

- Very Rare Category 5 on SS Scale not Australian Scale
- This is occuring At the Very End of the Season
- Possibly Smallest Eye ever in the Southern Hem.
- Lowest Pressure Ever in Southern Hem.
: HurricaneMyles we need a storm to talk about over her how mean more weeks do we have to go in tell the start of hurricane year 2006 i think we are going to see a lot of pinhole eye for are hurricane year 2006 like they are seeing over there and is it odd to see a lot of the pinhole eye over there i think it is the 3rd pinhole eye for them this year
Oh boy! Eye becoming starting to clear out on visable Sat. ERC is coming to an end!
Hmm...try again.

109. jeffB
OK here is the proof. What temperature are you most comfortable in? 68 degrees to 72 degrees is the answer.

Here's the proof. What are you most comfortable in, air or water? Air is the answer. So, if we DRY UP the entire ocean, the fish should still be perfectly happy.

I swear, it's getting so that the best part of this blog is seeing what inanity 'buster will come up with next.
Wave model for the area. There's a Java loop on the upper right. You can see the waves drop from aproaching 35' down to around 25' with the eye wall replacement.
I think that another strengthening to cat 5 is possible. The whole thing is controled by the wind shear. If the wind shear stays low all the way until landfall, then we may just have another storm close to Katrina's standards.
Agreed Levi32. Windshear has increased slightly since Glenda bombed to 898mb. We'll see if that inhibits her from getting close to that intensity again.
113. Inyo
they still do cloud seeding in the mountains of California, and it appears that it does increase precipitation in these areas. However, it is probably at the expense of areas downstream. Unless you can increase the evaporation from the ocean (as with global warming) you can't increase total global precip.

however, the idea that cloud seeding weakens hurricanes is a tenuous one at best, and to me seems counterintuitive. It seems to me that increased condensation on nucleii would release heat and if anything, intensify the hurricane. perhaps finding a way to remove nucleii would reduce its strength but could also lead to severe droughts.
Actually HurricaneMyles, have you noticed that the eye is more in the center of the convection since this morning? Before, easterly wind shear had pushed the bulk of the convection west of the center. Now it is much more symetrical.
The convection does not look that symmetrical on IR:

Well, maybe the convection on the SW side is a little weak, but look at the eye, if you look at a loop since this morning, you will see the eye is much more in the center of the whole thing. That means less shear than before. Also she is almost twice as big as when she formed.
Oh my! Glenda's eye has shown up clearly now on IR.

Hmmm, she may be ready to bomb again. Here is an IR floater loop. You will see what I mean about the shear. Look at her grow...
Agreed, Levi, that on IR the convection on the right side of Glenda appeared more sheared and compressed then she appears now.

If you look at this loop you can see she still had the 'buzzsaw' look of a very powerful hurricane, and shear didnt look to be a problem.
Agreed there Hurricane, the shear didn't affect her very much, but now there is less shear, so she has more room to strengthen. That is the dangerous part for Australia.
Looking better on visible:
darn, lets try that again:
am I doing something wrong?
There we go.
Here is a great forecast model page for Glenda. Intensity forecasts and tracks are available.
Oh boy... I noticed that one of the models forecasts Glenda to intensify to 160 kt (185 mph, equal to Wilma at peak intensity) - at landfall.
Yes Michael I noticed that. That is nerve racking to think about. I hope that doesn't happen.

Well I have to head off to bed so goodnight everyone. We will see how Glenda is doing in the morning. Tomorrow will be a very exciting day.
This is really something to watch!
130. lemmo
Rainfall here

Latest IR, showing eye still clearly visible but deepest convection off-centred.
Yeah, the eye just isn't quite getting up. Indistinct on recent IR.
buster: Go ahead prove me wrong!!!!

It's your new proposal, buster. therefore, the burden of proof is on the affirmative side, i.e. you.

we don't have to prove you wrong, you have to prove you are right.