This thread is for any questions relating to cyclones: low pressure systems, east coast lows (ECL), tropical cyclones (TC) etc.

There seems to be no shortage of questions since the start of STC Ului, so it seemed appropriate to have a specific thread just for this purpose.

All experts out there in forum land, please feel free to add your 2c worth through answering questions. Hopefully this thread can then become a resource in its own right.

Thanks,

Susan

Thanks snugaroo maybe i wont feel like such an idiot in here. First Question for the forum any links that you guys can share for the precipitation and other forms of charts that document the coral sea. Most i have found only show the coastline of australia.

*quickly rifles through her favourites*

Ok here we go:

ECMWF: http://www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!0!Australia!pop!od!oper!public_plots!2010032312!!/ (the forum hates this link, best to cut and paste it)

MTSAT (we are in the 'east' bit): http://www.goes.noaa.gov/sohemi/

Precipitation: http://www.radar.strikeone.net.au/?fuseaction=loops.cola%20%20%20&modelID=4&modelType=18

Lightning tracker at Mareeba: http://www.gorgecreekorchards.com.au/

Good chart for shear, shear tendency, steering winds, divergence etc.
http://cimss.ssec.wisc.edu/tropic2/real-...dvg&zoom=&time=

Oo nice one FR thanks for that, *adds to favourites*

THanks guys thats a start for me to start having a look at been diggin out the ole brain cells the last few weeks. With renewed interest.

Here's a good website nitso posted up in the Coral Sea thread before the end of last year.

http://www.theweatherprediction.com/basic/pressuretypes/

Main index: http://www.theweatherprediction.com/habyhints/

I actually have a question myself. In the WA cyclone thread there was quite a bit of discussion on the MJO (Madden Julian Oscillation) and its role in providing the right conditions for TC's to form. What are people's thoughts on this, I know there are varying opinions. Would love to spark a healthy debate on the subject

Greats Sites Thanks guys.. This thread was a great idea!

Ok ,here I go again ,into the deep end with a daft question
( to some ).

In a cyclone ( i have never been in one thankfully ) can someone describe for me what its like once it 'hits'...

I 'imagine' screaming winds, and wonder if there is HUGE thunder and lightning too??? Like a super magnified storm .I know that we can 'see' lightning stikes on the charts as 'crosses'..

...second part of question: If there is thunder and lightning, is it more scary than a bad storm ,or is it the winds that are more scary ?

You can see from my sig line why I ask ,thanks in adavnce, if anyone answers ,lol

Astra if you go to this Thread

http://forum.weatherzone.com.au/ubbthreads.php?ubb=showflat&Number=850916&gonew=1#UNREAD

Trav and Nitso sat out Ului and video taped some footage they have loaded up turn you volume up when watching it and you will hear the WIND and see the rain and wind etc.

I have expereinced two cyclones, both having lightning but no thunder. The winds are the most frightening aspect of a cyclone, together with rain, its very noisy.

Thanks Denise, I saw that thread, did look at a couple the other day,but I just went back and played them all , this post is the best for me! 853925, You can really hear the wind ,without the guys talking, ty and ty to Trav and Nitso !!! for the vid...It helps to know what you may be up against one day.

ty Tempest, i was told once that the wind in a cyclone sounds like a 747 ....
I think I just want to get myself 'informed' , so if we do get another one down this far , I can know more ,about what to expect.
ty

Whenever lightning is produced, thunder is produced as well. CC lightning is more common though in a cyclone than CG therefore the thunder is not quite as load and noise from wind and rain will over power the thunder noise. There would be no 'HUGE' lightning or thunder, well at least no bigger than any typical storm.

I remember in Tessi that the noise was dependent on wind direction, there was a roar from the wind going through trees but then if it changed slightly and got funneled between building, a 'howl' developed.

Wow that sounds really quite awful FR!

During Cyclone Ului I witnessed about 100 flashes in North Mackay (though these were electrical faults not lightning). Three of these flashes were enormous bluey/greenish glows that illuminated everything, and also coincided with the strongest wind gusts. Also after each of these glows a section of the power grid went out.

Being on the southern side of the Cyclone, winds during the afternoon prior to landfall were from the south, then as the night went on and Ului crossed the coast and travelled inland the wind direction gradually changed from S to SE to E to NE to N.

This new thread is a great idea, thanks Snugaroo. Although to get a better understanding of cyclones i think i still have a lot to learn about the weather in general so occasionaly I may have a question not directly related to a cyclone (hope thats ok).
Cyclone question - Wanda was a weak cyclone when it crossed the coast near Maryborough.
The winds associated with the system reached their peak in the night after landfall. Is it normal for a cyclone to intesify after landfall? I thought that they weakened when they hit land.

There are no such thing as dumb questions. If you have a question and you think it is dumb ask it anyway. If you don't know something then there are probably others who also don't know but have been too scared to ask.

Good idea for a thread and to help things along in the Tropical and Central Queensland thread there is a sticky for Tropical Weather links. http://forum.weatherzone.com.au/ubbthreads.php?ubb=showflat&Number=588030#Post588030 There is a mass of links in here but some are no longer working so it would be best to work through them and see which ones are of interest to you.

For those who have children and want more information you can download the Stormchasers Game. I have posted links to this in a couple of threads now. If you want to see and hear the destruction of a Cat 4 Cyclone then there is some home footage shot during STC Larry when itcrossed the coast at Innisfail. Here is the link http://www.bom.gov.au/storm_watchers_game/ It is 210MB download which would take days with dialup and chew a big hole in a limited adsl download so try your childs school library or local library. The game is free to download.

To answer the question about noise it is a combination of a lot of things but as FR said mainly the sound produced is caused by tunneling effects from natural, trees, bushes, rocks, hills, gullys etc and man made objects, but it also comes from other things as well. Tearing guttering and roof sheeting has a very high pitched wail that once heard won't be forgotten in a hurry, sharp cracks as tree trunks snap, hail like sounds as small bits and pieces of debris (twigs, sticks branches, tin cans, balls, bits of swing sets, palm fronds, rocks, sand, gravel, peices of picket fencing, roofing iron etc) are hitting the house, windows and roof and yes it can be as loud as standing behind a 747. I have been through or close to the centers of 5 cyclones (Including one in which we spent two days under a tent - hootchy- as TC Steve went passed us on a military exercise at Tin Can Bay) and each one has been subtly different when it comes to noise, lightning thunder and wind. During Tessi we had several lightning strikes within 600m of my house which we barely heard such was the noise.

We couldn't work out what a high pitched scream was during Tessi. It was comming from the corner of the house closest to the wind and we thought it was part of the roof giving way. I did a quick inspection of the exterior of the house as the eye passed ocver us and put it down to the coax cable from my TV antenna coming loose from its mounting bracket. The wind blowing through the bracket was causing the noise so I jammed the coax back in with some gaffer tape and it stopped my kids and my wife freaking out. Not the smartest thing to do climbing on to a roof in the middle of a cyclone but we all do things we look back on and say WTF was I thinking?.

The main part of the cyclone may have passed over the coast but gale force winds may still be blowing up to 36 hours after the original cyclone has passed over you. This is because the entire 'system' that contained the cyclone hasn't completely passed over you yet.

The BoM normally issues strong wind warnings for the next 24 hours after a cyclone has passed. The reason for the reintenisfication can be from sevearl factors but most often than not it is beacuse of the conditions that created the cyclone in the first place including high sea tempratures, low shear etc.

Thanks SBT,
Cyclone Rewa formed on 26 December 1993. It looped around the Coral Sea for almost a month, crossed New Caledonia and the Solomon Island, and dissipated on 21 January. Rewa was the longest-lived South Pacific tropical cyclone on record, lasting 25 days, from 26 December to 21 January.
After watching back at Ului i noticed he seemed to sit still(but was moving rather slowly) how long could a cyclone survive if it were to stay in the one area and not move about like Rewa did?

I have a question that results from the strangest observations I saw during the cyclone.

As the eye passed over Hamilton Island, and for several hours afterwards, the temperature climbed rapidly on the AWS into the low 40's. To me, this seems impossible, or am I wrong and there is a phenomena that makes this possible. I notice there are now no temp records recorded in this current months historical data from BOM.

Thanks in advance.

Homer

I had been wondering about the difference between Hurricanes and Cyclones and found this - just incase anyone else was wondering.

Cyclones, hurricanes and typhoons are all essentially the same thing, they simply receive different names depending on where they occur.

-- Hurricane: a violent wind which has a circular movement, especially found in the West Atlantic Ocean. A hurricane is actually a violent storm formed with water which causes heavy rains and fierce winds and they can cause flooding of streets and homes.

-- Cyclone: a violent tropical storm or wind in which the air moves very fast in a circular direction. They can be formed over tropical waters, bar the Southeast Pacific and the South Atlantic Oceans. Technically, all hurricanes are cyclones but not all cyclones are hurricanes: if their wind speed is over 74 miles per hour, they're hurricanes, if not, they're just cyclones or tropical storms.


-- Typhoon: a violent wind which has a circular movement, found in the West Pacific Ocean.


Have you ever been a cyclone?

The 1995 season ended with Hurricane Tanya, the first storm to be assigned a name beginning with 'T' since hurricane naming began in the Atlantic basin in 1950. Now I feel special. :-)

Hi Homer,

I think we decided it was probably a malfunction of some sort, although others may be able to elaborate more on this.

I thought other would be learners of Cyclones would love to see this i happen to find it just doing a general search.

http://www.bom.gov.au/weather/qld/cyclone/tc_larry/Larry_report.pdf

Thats interesting DeniseEm, as we are learning BOM and the likes are still learning and improving too

I always thought that typhoons, cyclones and hurricanes were all the same thing, (except for the names of course).

I thought I should also add some definitions. These comes from www.dictionary.com

Cyclone: "a large-scale, atmospheric wind-and-pressure system characterized by low pressure at its center and by circular wind motion, counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere." <---- this can occur anywhere, intense ones can be called 'extra tropical cyclones' meaning they are outside the tropics. I assume that East Coast Lows (ECL) fall into this category.

Tropical Cyclone: "a cyclone that originates over a tropical ocean area and can develop into the destructive storm known in the U.S. as a hurricane, in the western Pacific region as a typhoon, and elsewhere by other names."

Hurricane: "a violent, tropical, cyclonic storm of the western North Atlantic, having wind speeds of or in excess of 72 mph (32 m/sec)."

Typhoon:"a tropical cyclone or hurricane of the western Pacific area and the China seas."

So, as Jaliza said earlier, cyclonic storms have different names depending on where they form (and in the case of hurricanes, how windy they are). Other than that they are all the same thing

Comparing the words “cyclone”, “hurricane” and “typhoon” is similar to comparing the words “hi”, “hello”, “g’day” and “Konnichiwa”.

Cyclones, Hurricanes and Typhoons are all the same. Systems below Cyclone/Hurricane/Typhoon strength also have various names. Here in Australia were refer to them as “Tropical Lows”, however other regions refer to them as “Tropical Storms” or Tropical Depressions”.

Different regions also have separate methods to categorize the strength of a cyclone. In Australia the strength of a cyclone is based on the systems maximum wind gusts, where as in other regions (such as the USA and Japan) cyclones are categorized by the average wind speed over a certain time length (Usually 1 or 10 minutes).

Also be aware that there is no set standard that links cyclone categories between various regions. i.e. a Category 4 cyclone in Australia may only be a rated as a category 3 in the USA.

Surely the WMO could come up with a single classification criteria for all TC's. It would be very handy for people around the world to compare their systems. Keep the local classifications for warnings and watches and advisories i.e. the American system for America, the Australian for Australia but for God's sake once the event is over and the public doesn't care anymore, it would be great to compare apples in Australia to apples in India to apples in America.

This WMO classification system could appear in technical bulletins and technical discussions only, so the unaware public doesn't have to know they even exist and that way they won't be confused by 2 different classification systems.

Just my thoughts anyway.

Sounds sensible. It just confuses the issue with the current system. One of Ree's pigs may have to fly before it happens though

This may help answer cyclone lightning questions

http://science.nasa.gov/headlines/y2006/09jan_electrichurricanes.htm

That's a great little article, very interesting. I hope they figure it out, looks like they have a nice puzzle there.

Nice photos in here to give an appreciation of eye and eye wall structure ( copy and paste the first address )

http://home.att.net/~typhoon1/index.html

http://www.noaanews.noaa.gov/stories2005/s2496.htm

Ok im still learning here and i was looking through some satellite pics on the bottom right hand corner of this sat pic is there something forming down there or is that just cloud rotation.

http://www.goes.noaa.gov/sohemi/sohemiloops/vsgoes.html

I wonder if someone could put a map up then draw on it showing us what we should be keeping an eye on, just so its easier to try and learn...Its hard when you dont understand what people are looking at. I'm enjoying learning about them.

There is indeed a weak (cold cored) low out there but the main cause is a series shortwave/upper troughs arcing up over that area (which isn't unusual for that part of the world). A long way away and no influence on Australia but good pickup nonetheless.

Yeah i knew there was no worry to Australia was just trying to teach myself to pick up on low's etc via the satellite pics and thanks for the explaination on this one helps greatly.

Good idea Jaliza what i did was looked at the low up top of Darwin then just searched through all the other sat pics to see if i could find something similar. Just to teach myself how to pick up on them. But yeah would be so much easier if when a low forms over in the coral sea if someone could Screenshot it and draw a circle around where they are talking about. In simple terms for us newbies.

If you want another good example of a cold cored low, keep an eye on the blob of cloud to the the area east of New Caledonia over the next 48 hours.
http://www.goes.noaa.gov/sohemi/sohemiloops/shirgms.html

This chart shows a very strong upper trough out there which should induce a little surface low within the next two days.


Upper trough begins to tilt:



GFS prog for Wednesday morning showing the surface low:



Again, nothing for the east coast of Australia to get excited about but still good to keep an eye on if you're learning.

Very nice explantion and pics Mega ill keep an eye around that area and i can see what your talking about with the satellite pics now too if u watch closely at the loops u can sort of pic the winds direction of travel. It will also be good for us learners to see the before middle and after of a low forming if it happens to form into a TC even better for us.

After taking a quick glance at the rest of the models I think I'll change 'should' to 'may' as GFS might be overdoing this system a fair bit ...either way it would not become a TC because it would be cold cored (and TCs are warm cored.)

Ahhh ok i get u now so it would have to be a warm cored one to progress into a TC thanks again for the explanation taking notes down as i go for referral later on will be so much easier once we have seen a few come and go and be able to pick up on them ourselves instead of having to ask if what we see is or not what we think it is. ( LOL if u can understand what im trying to say )

Is this a Cold Cored Low starting to form near New Caledonia.

http://www.goes.noaa.gov/sohemi/sohemiloops/vsmtsat.html

LOW [1009HPA] ANALYSED NEAR 18S 167E AT 300600 UTC SLOW MOVING.

Just thought with the cyclone season looming might be a good time to revive this thread for all us NOOBIE cyclone freaks.

Good idea Denise, we are sure to get a lot of cyclone questions if this season lives up to its name

After various conversations with numerous people over the years, it’s become quite evident to me that the vast majority of locals (both new to the area and long time locals) are greatly unaware and uneducated about cyclones. I’m not picking on anyone, but a little bit of information can be beneficial to us all. So with the threat of a potentially very active season looming, I thought I might take the opportunity to try and explain some of common issues I often encounter. Of course I’m not a cyclone “expert” and certainly don’t claim to be, so if others have something worthwhile to add, please don’t hesitate.

Righteo, starting off with the basics…. in case you didn’t already know, cyclones are large rotating systems originating over tropical waters and are capable of producing very heavy rainfall, storm surges and wind speeds in excess of 300km/h (in the most severe cases).

Of course here in Australia, cyclones are rated by categories numbered 1-5 based on how strong the highest wind gusts are estimated to be within the cyclone’s zone of greatest winds (just outside the cyclone’s eye).
Category 1 = less than 125km/h
Category 2 = 125 – 164km/h
Category 3 = 165 – 224km/h
Category 4 = 225-279km/h
Category 5 = more than 280km/h
(Note, Tropical Cyclones of category 3 or higher intensity are called “Severe Tropical Cyclones”.)

Anyway I won’t get too stuck into this detail as this type of information is available on the BoM’s website. Click HERE

OK now then, getting to some of the issues and misunderstandings…… A few of months ago I was talking to a bloke I know (55 years old and lived in Mackay all his life). He was quite surprised by the winds he experienced during Cyclone Ului (March 2010). But it wasn’t the strength of the winds that had him confused, rather the direction they were blowing from. Living 120km south of where Ului made landfall, naturally he expected the winds would blow from the north. Makes sense doesn’t it? Cyclone to the north = winds will blow from the north. WRONG. Because cyclones are large rotating systems, depending on where you are positioned in regards to the centre will determine which direction the winds will be blowing from. In the Southern Hemisphere winds rotate clockwise around Cyclones.

So if a cyclone is in your vicinity, as a rough guide:

If the Centre of the Cyclone is located to your NORTH, winds will blow from the EAST
If the Centre of the Cyclone is located to your NORTH-EAST, winds will blow from the SOUTH-EAST
If the Centre of the Cyclone is located to your EAST, winds will blow from the SOUTH
If the Centre of the Cyclone is located to your SOUTH-EAST, winds will blow from the SOUTH-WEST
If the Centre of the Cyclone is located to your SOUTH, winds will blow from the WEST
If the Centre of the Cyclone is located to your SOUTH-WEST, winds will blow from the NORTH-WEST
If the Centre of the Cyclone is located to your WEST, winds will blow from the NORTH
If the Centre of the Cyclone is located to your NORTH-WEST, winds will blow from the NORTH EAST

Bear in mind, as the cyclone moves the wind direction will change accordingly. Therefore if a cyclone passes in your vicinity, the wind may change direction several times in just a matter of hours.

During a cyclone if you notice winds increase in violence for several hours then suddenly ease to almost calm conditions, contrary to many peoples belief, IT DOES NOT MEAN THE CYCLONE HAS ENDED – rather you are currently in the calm eye (centre) of the cyclone. During this time it is NOT advised that you venture outside as winds will again return to their previous strength from a different direction. There is no set rule for how long calm conditions will remain for. Several factors determine how long the calm will last. Some of these include…….
• The size of the eye:
Most cyclones have an eye diameter of approximately 20 - 40km. However the eye of some cyclones can be as small as 5km, and the diameter of the largest eye on record is 320km.
• Your location within the eye:
The calm conditions would last longer if the very centre of the eye passed over you, rather than if you were located only just within the edge of the eye.
• The speed the cyclone is moving:
Cyclones move at different speeds. Generally I would class a slow moving cyclone one that travels less than 10km/h, and a fast moving cyclone one that travels more than 25km/h. If I recall correctly, when cyclone Larry made landfall he was travelling at 30km/h. Obviously the faster the cyclone is moving, the less time it will take for the eye to pass over - therefore reducing the duration of calm conditions.

I might also add that a cyclone moving at a slow speed will cause more damage than an identical cyclone moving at a faster speed as the destructive winds within the core will take longer to pass by. i.e. a house will suffer more damage during 200km/h winds lasting 4 hours rather than only 1 hour.

Another belief we can throw out the window is………
I often hear people say “if a cyclone moves faster, it will lose intensity”. THIS IS NOT ALWAYS TRUE. Yes in many cases this will occur, particularly those off the Qld coast that are caught by strong upper level North-Westerly winds and pushed away to the land of the sheep shaggers. But under favourable conditions cyclones are capable of accelerating while still intensifying. A recent example of this was just earlier this year when Cyclone Ului re-intensified to a category 3 cyclone just prior to landfall, while travelling at a speed of 27km/h and continuing to accelerate. So don’t always assume that if a cyclone is increasing in speed that it will lose its intensity.

Moving on……..
Another lesson that is important to remember is:
If you have experienced a cyclone in the past, although the cyclone may have been ranked a category 4 system as it made landfall, it doesn’t necessarily mean the winds you experienced at your location were of category 4 strength.
For example;
Cyclone Ului made landfall as a category 3 system at Airlie Beach with winds near Midge point probably in the vicinity of 180km/h. Yet about 70km to the south, the highest wind gust recorded in Mackay was only 113km/h – which is only the equivalent of a category 1 cyclone. Despite this, I can guarantee you there are hundreds of people in Mackay thinking they experienced winds equivalent of a category 3 cyclone. The bad news is, if another cyclone was to hit Mackay next week as a category 2 system (less intense) those people would assume “Well if we had no troubles with a category 3 cyclone, then if we were hit by a category 2 cyclone there would be even less damage”. THIS IS NOT NECESSARILLY TRUE. This is because Mackay was located outside the zone of maximum winds; therefore Mackay didn’t feel the full force of the cyclone. So although a Category 2 cyclone may seem tamer than category 3, depending on where is makes landfall, and how far the radius of maximum winds extend from the centre will determine what the wind speeds will be like at your location.

This brings me to another important issue. No two cyclones are the same – they all have their own individual “personalities” (i.e., some are big, some are small, some are fast, some are slow, some are predictable, others are unpredictable, some live longer than others, and the list goes on..…..) One of the biggest issues here is that some cyclones are larger than others. When I say “larger” what I mean is that the area of destructive and gale force winds extend to a much greater diameter.
Generally, most Qld cyclones have gales (winds above 63km/h) extending about 200km from the centre of the cyclone. In 1974, gales from Cyclone Tracy (arguably Australia’s most significant cyclone from the last 100 years) only extended 50km from the eye. On the other end of the scale, at one stage Cyclone Justin (1997) had gale force winds extended more than 700km from the centre of the cyclone.

So for another example….
When Cyclone Larry made landfall at Innisfail as a category 4 cyclone in 2006, Townsville (about 200km away) recorded a maximum wind gust of 71km/h. Yet in 1976, Category 3 (less intense) cyclone John made landfall just north of St. Lawrence, but managed to produce a wind gust of 156km/h at Gladstone (also 200km south of where the cyclone passed by). So if you live in Townsville, and a Category 3 cyclone is forecast to make landfall at Cairns, DON’T ASSUME that because the cyclone is further away that winds will be of a lesser severity to those you experienced during cyclone Larry.

Finally, despite the amazing technology about these days, cyclone forecasting is still far from perfect. Making it more of a challenge for our local weather bureau is the fact that Cyclones around Australia move more erratically than those from anywhere else in the world. And even when there is a high degree of confidence in the forecast track, there is ALWAYS a level of uncertainty. So keep that in mind, and always prepare for the worst.

Anyways, that’s about all I can be bothered typing tonight. I might add a few more issues as I remember them or after having further conversations……….

YERY useful information! I do have one question though. How to I translate this to sheeperish to warn my furry friends back home that a TC may be approaching from Skippyland?

thank you wet wet wet for posting this it is very much needed we can go back to your post and clear things up quickly when things get a bit hairy

Very well written!
I agree that the winds we experienced here in Mt Pleasant on the hight of Ului were that of only a Cat 1. So people NEED to understand all the stuff you wrote. Well Done!

Fantastic post WWW, will sticky this thread.

Hi guys, as the cyclone season is almost upon us, and here in SEQ we are to expect a possible cyclone crossing this year. I thought it would be good to ask those of you who may know, what the potential damage could be?

For example, myself, having not ever experienced any kind of cyclone etc, i would love to see one up and close and personal! The only problem being, is that i live in a high rise in surfers facing east, surrounded by glass and with the foundations built in sand. So, if anyone could put my mind at ease here that would be great. This would also be very helpful for those who live in tall buildings!!

Would a cyclone be capable of a toppling a tall building, either by wind alone or by storm surge etc?
What strength cyclone would be necessary to blow out all of the windows?
Would the winds be much greater at a higher floor?

Would you even recommend staying in a high rise during a cyclone?

Hope you dont mind so many questions, but i remember someone quoting on a previous thread that 'if a severe cyclone ever hit the gold coast, we would be obliterated' or words similar to that!

Thanks in advance

well in my mind a cat 1 or 2 we could cope, just look at the ECL's in august 07 and may 09, they were packing cat 2 winds!! (i think)

there would be severe erosion along all of the beaches, im not quite sure if i can answer your other question as im not expert but for things to get really bad a cat 3+ would have to cross the coast

I'm not a builder but any building structure has to be approved by the council basing that off a 100yrs of weather history roughly round abouts to stand up to the elements, the foundations built on sand are one of the highiest strictest standards for a slab approval so the ground level structure should be well and truly be underground a height of a power pole or more perhaps depending on the height of the building
The glass installed should be thickened glass and shatter proof by strict standards, and with the strong winds most of the modern buildings are designed to give a little in the structure to reduce stress.

So if a servere cyclone paid a visit a Cat 4-5 for example I would be on the ground floor just in case! mother nature does rule over us.

I know its not a TC forming or anything but can someone explain to me the circular motion and what is causing it around co ordinates -170 , -25 on these 4 loops.

http://www.goes.noaa.gov/sohemi/sohemiloops/vsmtsat.html

It is a weak low positiond SE of Noumea(I think)

Thanks i thought so but wasnt sure as i didnt see it written on any of the maps with a L.

Some very important information there WWW.

http://www.bom.gov.au/storm_watchers_game/ Stormwatches game to help children prepare for a cyclone. If you can't download it ask for it at your local library.

Thanks WWW, that was a good and informative read. ...Baaaa.

Bunnings in Spence Street Cairns have about 10 pre-prepared "Cyclone Emerngeny Kit" trolleys ready for service as Xmas gifts for $79, and includes a battery drill. Bloody wonderful.

The most amazing thing i found when core punching into the eye of severe tropical cyclone ului and being in the eye.....was the insane humidity and heat inside the eye.
The tempreture in the hour we were in the eye increased 2-3C with humidity levels over 95%. The heat index was well above thirty degrees, and this was at 2am !!!!!

Since ULUI packed most of its punch into its SW quadrant, due to its quick organisation and fast forward movement, the other half of the cyclone after the eye was not that bad.
We recorded a gust of 144 kilomtres a hour about one hour before we went into the bad stuff near the eye wall. So we assumed that we would have got gusts within the 155-170 kilometre a hour mark. HOWEVER on the other side of the cyclone we probably only had a top estimated wind gust of only 90-100kmhr. Yes its still damaging, but nothing compared to the very destructive core.

I always had wondered how fast the wind speed picks up in the otherside of the eye wall. I was astonished at how fast it actually does ! In 5 minutes it went from DEAD calm wind gusts, to gusting to 75 kilometres a hour....IN FIVE minutes....

Imagine if this cyclone actually packed a punch on the eastern side. I now see how people can get caught out and be injured, or worse killed in tropical cyclones. If this system was a category 5, we could have gotten hit by 200kmhr winds on the return side in less than 10 minutes. Thats not good news if your stuck outside, or in a spot of trouble.

Just my 2 cents worth.

hey Trav been through a few cyclones and agree that the eye is deceiving... but for me the most intriging part of a cyclone and the thing that newcomers to FNQ need to understand. I have stood in my backyard and listened to the birds chirping loudly and the frogs singing straight after the wind has died down then all of a sudden all goes quiet and then you hear what I describe as the sound of a freight train roaring towards you... this is the otherside approaching. What people must realise is that the calm of the eye can last from a few minutes to much longer depending on the severity of the cyclone and stay inside until all danger has passed

WWW fantastic informative write up..thankyou. I've been through a few cyclones and agree each one is different. People get too complacent sometimes and thats when the bad stuff happens. I was shocked when cyclone Ului was heading for us and people kept saying 'it wont happen' Mackay never gets hit. But I still went into survival mode and did my usual preparation ...glad I did. Also amazed with the number of ramshackle houses in Mackay that there are no cyclone shelters !!! I've only been in the Mac for 5 years...but wow no cyclones shelters???? What the....???? Also the tv warnings were out of date and totally useless...thats when I joined this group. I'm fairly used to having good comms during the warning period, maybe the powers that be need to study Darwins cyclone response plan .

Apart from the radio broadcast alarm sound, I found the scariest thing was the stuff hitting the roof and wondering if anything was going to break off. We had 1 window that was a bit dodge and it was flapping about in the wind and I kept thinking that it was gonna fly away (luckily it didn't).

It got extremely hot inside the eye wall, I couldn't believe how calm it was. When people said it was calm I had images of light breeze and rain. But there is nothing, no birds, no animal or wildlife movement of any kind. Just dead silence. Then comes the breeze, you hear a gushing noise then the tree outside moves a bit and you think "Ah, maybe its not as strong this side.." Then Wooosh!

I think there is an extra category that are in a category all of their own, which a fortunately so rare they may only impact the coastline only once or twice in a lifetime. That is the "sub 900 cyclone". That would be our worst nightmare if one of those monsters scored a direct hit on Cairns. I just trust Australia has an emergency response and management plan in place no matter how unlikely such a scenario is.

could you explain what a "sub 900 cyclone" is? i cant find anything about it on the net?

I would assume that a sub 900 cyclone is a cyclone air pressure below 900hpa.

well duh!! how stupid of me!! haha

thanks squeak!

and lets not talk about a "sub 900 cyclone", that would be a disaster anywhere along the entire QLD/WA/NT coastline....

I have a question in regards to this quote from WWW

"Generally, most Qld cyclones have gales (winds above 63km/h) extending about 200km from the centre of the cyclone. In 1974, gales from Cyclone Tracy (arguably Australia’s most significant cyclone from the last 100 years) only extended 50km from the eye. On the other end of the scale, at one stage Cyclone Justin (1997) had gale force winds extended more than 700km from the centre of the cyclone."

The distance your referring to is that down the coastline or inland as well. Emerald is roughly 300klms to the east of Rockhampton so if a cyclone was to hit Rocky with Gale winds that spanned about 300klms would they be felt in Emerald as well. Just curious if the same thing happens over the inland geography as the coastline.

Hey Denise,

Generally that more so applies to cyclones that are over open water which aren’t affected by the friction of land. Also, the radius that gales extend from the centre of a cyclone will also vary in each quadrant. Typically on the east coast gales will always extend further from the eye on the southern side of the cyclone due to a tighter pressure gradient between the cyclone and a high pressure system to its south.

However more to the point, if a Severe cyclone made landfall at Rockhampton, Emerald would certainly cop gale force winds. Although as the cyclone moved inland and weakened, the impact would not be as severe compared to areas on the coastline that endured its full force. For example, if a category 5 cyclone made landfall between Mackay and Rocky, I would suspect the worst case scenario for Emerald would be maximum winds in the category 3 range (i.e. up to 165km/h).

And yes places like Emerald have suffered damage as a result of cyclones in the past. In 1918 the 'Mackay' Cyclone (A very large cyclone) reportedly uprooted thousands of trees and caused structural damaged out at Clermont. It also resulted in Rockhampton’s highest flood on record which still stands today - nearly 100 years later.

Also, in 1976 Cyclone David (another very large cyclone) made landfall near St Lawrence. And although I haven’t come across any info relating to damaged caused at Emerald, I can assure you wind gusts there would have exceeded 100km/h.

Anyway, what’s of concern here is that both of these very large and intense cyclones I just mentioned occurred during strong La Niña seasons. And if you didn’t know already, we are currently in the middle of another of those strong La Niña seasons........

Thanks for the very detailed response WWW with the way this season has been so far anything is possible and its good info to have on hand.

I have been searching the net for evidence of the Australian coast being hit by a sub 900 and the most likely candidate was cyclone Mahina way back in 1899 at Bathurst Bay which probably did go sub 900. Even Cyclone Monica did not go sub 900. The most recent in our region was Cyclone Zoe which impacted Vanuatu which did in fact go down to 890 and the deadliest of them all worldwide was Typhoon Tip which was not only sub 900 at 870 but was simply huge. So massive that if storm like that were to impact Queensland it would be beyond thinking about, and I should assume if it passed between Townsville and Cairns then both those cities would be obliterated on top of the unprecedented disastrous flooding it would cause as it moved inland. Sub 900 Cyclones! we don't want you here.

Just did a recull of my lists for cyclones and not having anywhere better to stick this decided that maybe it should be in here.
Criteria for selection was cyclones to have either directly impacted or had a impact causing death or damage to an area from Noosa to Tweed Heads.
So anyway here they are:

Sunshine Coast to NSW Border Cyclones since 1864

1) 17 - 19 March, 1864. The first recorded in Queensland. Gales in Brisbane. Damage to stores, houses, signs trees and gardens blown away. Stone jetty at Cleveland washed away. Wind and rain damage at Toowoomba and Gladstone.
2) 26 - 28 April, 1867. Southeast Queensland flooded. Wharves covered in Brisbane. Brisbane, Logan and Ipswich suffer structural and tree damage. Bridge at Ipswich destroyed.
3) 11 March, 1890. Tropical cyclone hits Brisbane. River floods - 360mm in 24 hours.
4) 2 January, 1892. Brisbane suffers damage.
5) 2 April 1892. Brisbane damaged.
6) 21 January, 1893. Brisbane homes and trees blown down.
1. 11 February, 1893. Small cyclone crosses near Bustard Heads causing further flooding in Brisbane.
7) 19 February, 1894. Tropical cyclones crosses east of Brisbane.
8) 2 April, 1927. Severe cyclone east of Gold Coast. Highest recorded tides cause disruption to shipping.
9) 14 February, 1928. Brisbane hit causing serious flooding with 5 people drowned.
10) 1 February, 1934. This particular cyclone travelled from the Gulf to northern NSW causing widespread damage and flooding. There was a 1.16 metre storm surge recorded as the largest on record on the Moreton Bay tide gauge.
11) 22 March, 1936. Seawards of Fraser Island
12) 4 April, 1946. East of Fraser Island causing flooding.
13) 23 January, 1947. Cyclone crossed near Caloundra with heavy gales and high seas. Flooding. 2 dead.
14) 10 February, 1947. Tropical cyclone crossed at Broad sound causing damage to infrastructure and some lives were lost.
15) 28 January, 1948. Cyclone passes east of Brisbane with wind gusts up to 96 knots at Lord Howe Island.
16) 24 March, 1948. Structural damage and erosion as cyclone passes over Fraser Island.
17) 16-19 January, 1950. Tracked from the Gulf to Sydney. 7 lives lost in NSW. 2 metre waves in Moreton Bay with houses evacuated at Sandgate.
18) 27-28 February, 1950. Crossed over Gladstone to Hervey Bay. Floods down to Brisbane.
19) 16 November, 1950. Tropical low crosses near Brisbane causing structural damage and one death.
20) 25-30 January, 1951. Cyclone moves around Fraser Island. Extensive damage to boats and buildings with one life lost at Caloundra.
21) 20 February, 1954. Cyclone crosses at Coolangatta. Widespread structural damage from Sunshine Coast to Gold Coast. Boats left in treetops at Beachmere. Waves at Kirra put 2 metres of water on the highway picking up cars. 900 mm rainfall recorded in 24 hours. 26 people dead.
22) 24 April, 1963. Cyclone stayed offshore but caused huge waves and erosion on south coast.
23) 28-30 January, 1967. CYCLONE DINAH. Severe damage at Heron Island then causing more destruction from Rockhampton to Grafton, NSW. Water knee deep in Hastings Street, Noosa from storm surge.
24) 22 February, 1967. CYCLONE BARBARA. Wind damage from Coolangatta. Crossed at Lismore, NSW.
25) 18 March, 1967. CYCLONE ELAINE. Moved past the south coast causing flooding at Logan and Brisbane with considerable beach erosion in other areas.
26) 2-4 April, 1967. CYCLONE GLENDA. Off shore of Brisbane. 16 metre waves near Gold Coast. 6 dead.
27) 17 February, 1971. CYCLONE DORA. Crossed the coast north of Brisbane at Redcliffe. Widespread structural damage with some flooding.
28) 11 February, 1972. CYCLONE DAISY. Hit Fraser Island. Over 200 homes damaged at Pialba and other areas. Severe flooding to the Gold Coast where a peak swell height was recorded at 8.3 metres.
29) 24 January, 1974. CYCLONE WANDA. Over the coast near Maryborough, it then caused significant flooding in Brisbane where 6007 homes were flooded. 13 people drowned and others died from heart attacks. The cost was $200 million (at 1974 value).
30) 6 February, 1974. CYCLONE PAM. Intense cyclone passed 500km to the east of Brisbane. Severe flooding and evacuation at Palm Beach
31) March, 1974. CYCLONE ZOE. Crossed the coast at Coolangatta then went back to sea. Floods in Brisbane with evacuations at Murwillumbah and Lismore, NSW.
32) 4 March, 1976. CYCLONE COLIN. Generated huge waves along south Queensland beaches after moving south from Fraser Island to southern NSW where waves were recorded off Sydney Heads at 12 metres in height. Several launches were sunk or destroyed when 2 metre waves entered Botany Bay.
33) 5-6 March, 1976. CYCLONE DAWN. Crossed at Fraser Island causing some damage and coastal flooding.
34) 24 February, 1980. CYCLONE SIMON. Passed near Fraser Island with wind gusts over 100 knots. Structural damage at Hervey Bay. Wave peaks recorded at 8.9 metres. (my first cyclone)
35) 15 February, 1981. CYCLONE CLIFF. Crossed over Fraser Island to Bundaberg. Flooding to Gold Coast (my second cyclone)
36) 3 February, 1990. CYCLONE NANCY. Crossed near Byron Bay in NSW. 73 knot winds recorded near Brisbane. Flash flooding in Queensland and NSW caused 4 deaths and costs reached $36 million.
37) 13 January, 1992. CYCLONE BETSY. Passed seaward of Fraser Island. Caused beach erosion.
38) 17 March, 1993. CYCLONE ROGER. Passed close to Fraser Island before moving back to sea and south towards NSW. Sunshine Coast sustained damage while winds and seas closed the Port of Brisbane. Brisbane station recorded waves at 13.2 meters.
39) 20 January, 1994. CYCLONE REWA. Stayed 100km off the coast but caused flash flooding around Brisbane which resulted in 4 deaths.
40) 26 March, 1998. CYCLONE YALI. Passed seawards off Brisbane heading south. Wind gusts of 54 knots and peak wave height recorded at 11.5 metres. Beach erosion from Sunshine Coast to Northern NSW.
41) BENI 2 - 5 February 2003. Beni caused floods from Rockhampton to the Gold Coast causing $10M worth of damage to public infrastructure. Waves were recorded to 8.5metres.
42) Hybrid Cyclone 5 March 2004. Waves to 14.2metres recorded off Stradbroke Island. Severe flooding from Sunshine Coast through Brisbane to Gold Coast.

What is a hybrid cyclone? I know there are tropical lows and lows which are not tropical, but I am new to this forum and haven't heard of a hybrid one.
42) Hybrid Cyclone 5 March 2004. Waves to 14.2metres recorded off Stradbroke Island. Severe flooding from Sunshine Coast through Brisbane to Gold Coast.

Looking at the BOM site for the Hybrid Cyclone (18) it followed a path which could be similar to the current Cyclone Anthony.

Bunnings in Townsville have cyclone kits near the checkouts too. A great idea.

My son wants to know where is Cyclone Anthony liable to go to? It currently looks like it is heading to New Zealand, but there is an increased curve south east in the latest BOM bulletin. One thing I have learnt about cyclones is they can pretty much go anywhere, like standstill and then change direction.

The stars in Townsville are beautiful tonight; as someone in Mingela said today, the cyclone has swept up all our bad weather.

Whoever said Townsville weather was - boring? We have quiet interludes in otherwise threatening cyclonic weather - this is not boredom! - just letting us have a quiet nap and until the next event. As part of the overall scene up here, we have crocodiles in all estuarine streams including those in the city, deadly box jelly fish and irukandji jellyfish whose broken tentacles in the swimming enclosures can still cause grief, in addition to sharks and dengue fever.

Cyclone Ului was the last major cyclonic event which came close to Townsville in Mar 2010 - it was category 5 for quite a while until it crossed the coast near Airlie Beach (3 hrs drive south) as a 3 or 2. Everyone who saw Larry in 2006 was worried about what another 5 would do. If the big cyclones hit a larger city with tall buildings, there would be terrible damage. It beats me why the councils allow 20 storey buildings in Tropical Australia.
Tropical weather always has the potential to heat up!
I well remember the frequent summer Brisbane thunderstorms and hail storms which strike just as everyone is trying to get home from work and school are not as frequent up here on the whole, but lately we are having thunderstorms a couple of times a week too.
When we lived in Mount Gravatt in the 1980s-1990s, we got a new corrugated iron roof because we were worried we might lose our old fibro roof in a storm. The old roof had holes the size of cricket balls which had been plugged with tar the roofer said. He was amazed. Over years, the tar had hardened, shrunk and then leaked with every storm. As a child, I lived next door and remembered a really bad hailstorm in mid 1960's where hail stones that size caused a lot of broken windows and holes in roofs of our neighbour's houses.

There is a link I found here concerning "hybrid cyclones"

Mmmmm, we are as ready as we'll ever be, almost.... but I must admit I have had the thought that, if a big cyclone did cross here , that I would do a 'runner' inland/west, in the car,
( with 2 dogs !), my other half says he would stay here...but ,after reading so much here, i think it's probably better to stay, well prepared, in your own home. I have never been through one and I don't want to , I can only imagine, the noise, frightened dogs, etc, what do people do with their dogs ? bring them into the house for safety yeah ? I reckon a small tranq would help them too, must ring vet !!!!!.
All very interesting, thanks all for advise and info.
Barb :-)

Keep up the good work guys and admin - for people like me that cant really read a weather map - its great for the expert interpretation. Quick question- I am in Cairns and when Cyclone Larry hit Innisfail. My pool water moved like a swell in an ocean. Freakiest thing I have seen. Is this from pressure?

Astra>>> I have a Labrador, he doesnt mind the cyclones much so long as he is next to me...A few days before , instead of sleeping he prowls around the yard and gets restless. Then he wont leave my side. He's pretty good really, I've always taught him not to fear thunder or rain. But during a cyclone he is like my second shadow. So I always prepare by cooking up some nice munchies for him that he can have during the cyclone, I suppose dogs need comfort food too.

I'm not one who follows the ways of the animals that much during storms etc...but I do believe in the behaviour of BOB my dog.

So long as you have the dogs with you and 'act ' like its normal to have blasting howling wind around...then they will be fine..just have a very good lead for them and something dry for them to lie on.

Thanks for that Windblown, They will be inside the house with me if needed, I dont care if we all have to get under a bed to be safe, beagles are cuddly right !!!! 1 of them is storm wary, the other not too bad. I can get jittery, but as you say ,you need to be calm so they feel safe, (bit like when my kids were little , they are big now and in Sydney !) So , harness leads, tasty treats ,good idea, its not like they are going to be wanting to eat a proper dinner and it won't last forever , only feel like it !! Be safe, you and Bob ....

Great post www - you would think that this sort of cyclone information would be taught in schools in Cyclone Prone areas these days. Having lived through a couple of doosies and had numerous near misses over the years, you get to know a little bit about TC's, however, as each one has a mind all of its own - this sort of information should be broadcast along with the warnings.

A little bit of education never hurt anyone!

One measure of the size of a tropical cyclone is determined by measuring the distance from its center of circulation to its outermost closed isobar, also known as its ROCI. If the radius is less than two degrees of latitude or 222 kilometers (138 mi), then the cyclone is "very small" or a "midget". A radius between 3 and 6 latitude degrees or 333 kilometers (207 mi) to 670 kilometres (420 mi) are considered "average-sized". "Very large" tropical cyclones have a radius of greater than 8 degrees or 888 kilometres (552 mi).[10] Use of this measure has objectively determined that tropical cyclones in the northwest Pacific Ocean are the largest on earth on average, with Atlantic tropical cyclones roughly half their size.[11] Other methods of determining a tropical cyclone's size include measuring the radius of gale force winds and measuring the radius at which its relative vorticity field decreases to 1×10−5 s−1 from its center.[12][13]
kilometres

1degree of latitude = 110.649klm
ROCI Type
Less than 2 degrees latitude Very small/midget
2 to 3 degrees of latitude Small
3 to 6 degrees of latitude Medium/Average
6 to 8 degrees of latitude Large anti-dwarf
Over 8 degrees of latitude Very large

I was advised by a builder to put a mattress against the inside of the garage door, then park the car next to it. Has anybody heard of this before?

Dawn I have heard that you put your wheelie bins between your car and the roller door. So when the roller door blows in it wont damage your car as much.

Thanks so much. I think the wheelie bins sound better.

Will keep the wheelie bins from becoming missiles, too- as they'll be out of the way! Double advantage!

http://flood.firetree.net/?ll=-27.8390,138.1640&z=13&m=7

World Flood Map

I have just been checking the storm track and have noticed it is on track for the center of the eye to be just 100 kilometers out to sea at full tide at Cairns at 9.30 in the morning. High tide without the cyclone would be 2.8 meters.

TOWNSVILLE EMERGENCY NUMBERS

Emergency Contact Numbers
Service Number
All Emergency Calls 000

Townsville Local Disaster Management Group
Coordination Centre 1800 738 541

Townsville State Emergency Service (SES)
Tarping/Branches Down
13 25 00

Police (Non life-threatening calls) 07 4759 9777

Ambulance (Non life-threatening calls) 13 12 33

Fire Brigade (Non life-threatening calls) 07 4771 2111

Townsville City Council
Emergency After Hours
07 4727 9000
4727 8999

Ergon Energy
Loss of Supply and Emergencies 13 22 96

Origin Energy
Natural Gas and LP Gas Emergencies - Leaks only 1800 808 526

RACQ
Road Reports 1300 130 595

Telstra
Faults 13 22 03

Townsville Hospital 4796 1111

http://www1.ewn.com.au/register/register.aspx
Early warning Network

http://www.townsville.qld.gov.au/Pages/disasterinfo.aspx#evacuations List of streets being evacuated due to storm surge.

Hi WWW, Mate can you provide another multi track set for us please, researcher.

Hey stay safe SBT! I've rellies in Vincent and I'm really worried about them.

Cyclone Tip:

Having been through a handful of cyclones in my short life...Winifred, Althea, Peter... I would recommend people put pool furniture, trampolines and other potential missiles in their swimming pools. The pool will prevent those items relocating to parts unknown and will need to be cleared of debris after the event anyway.

Cyclone Tip:

The story about opening a window on the leeward (downwind) side of your house is an old wives' tale. It basically sets up a Bernoulli vacuum in your house, reducing atmospheric pressure inside the structure as wind rushes past and sucks air out. That increases downforce on your ceiling and roof but will also increase vacuum loading on the inside of the windward walls of the structure, increasing the likelihood they will fail.

Close all windows and doors and rely upon the structural integrity of the building.

Cyclone Tip:

Everyone hears this one but it's worth repeating:
Bathrooms, toilets and hallways are the strongest structural areas of the house... especially if they have small windows and strong doors. Shelter within those areas and remember that even if the roof comes off they are still safer than being outside.

NB Large concrete block walls are prone to collapse in very high winds. An example of such a wall is usually found on the side of a garage, where a 6-8 metre span of brick wall may be subject to high winds.

Cyclone Tip:

Clean your bathtub out with dishwashing liquid and rinse well. Then insert the plug and fill with fresh water and cover with a large sheet of plastic. It may be your best source of fresh water in the aftermath of the storm. Utilities may take up to a week to reconnect water services.

is holliways beach experiencing a big storm surge are houses near the beach in danger ????

I need some answers please Weatherzone.

The highest wind gust recorded was at Lucinda point and reached 180km/hr. Lucinda is 40km south of Cardwell that lost 200 homes. Carwell is clearly in the centre of the storm as Tully and Mission Beach only lost 20 homes each. So if Lucinda point recorded 180km/hr how come reporters are referring to 290 km/hr winds??

Secondly - why has Weatherzone removed the Lucinda Point wind record from it's site and replaced it with Townsville airport?

Lucinda AWS must have gotten damaged and was reporting wrong data, just after the 100knot gusts lucinda was reporting 46.7C, so there was something wrong with the AWS so the BoM took it offline.

That was the same thing with South Johnstone (spelling :p), except it was taken offline much earlier for a reason i dont know.

we just have to wait for the report form the BoM on YASI then we will get a detailed analysis of the entire event.

Thank you !SCHUMMY!

I still have the page - it reached 47 at the height of the storm but soon settled back down.

http://www.weatherzone.com.au/station.jsp?lt=site&lc=32141&list=ob

BTW the temperature measuring equipment is different from the wind measuring equipment.

Divergence and Convergence. My understanding is like a cycle.... Air going into low level covergence systems going upwards and heading back to divergence zones?!?! Ive Goggled and stuff but im still wondering if anyone can expend?
Also What are we looking for on http://cimss.ssec.wisc.edu/tropic2/real-...dvg&zoom=&time= to see ideal conditions for thes two zones to be in for favourable Cyclogenesis?.... I understand the yellow numbers on yellow line mean Knots? Am i correct? Do I treat the two some what like Highs and lows? (IE Direct of Convergence speeds is Anti clockwize Divergence direction is Clock wize?)

Im Slowly understanding the rest of the stuff but just wanna be sure on this topic? I have also posted on Cyclone Advice and informantion but i also thought i would post on tropical cyclone thread because I thought it might help others like myself understand?!?!
Thanks for putting up with my Mind boggling questions from time to time!

Regards
The TUNA FISH

Divergence and Convergence. My understanding is like a cycle.... Air going into low level covergence systems going upwards and heading back to divergence zones?!?! Ive Goggled and stuff but im still wondering if anyone can expend?
Also What are we looking for on http://cimss.ssec.wisc.edu/tropic2/real-...dvg&zoom=&time= to see ideal conditions for thes two zones to be in for favourable Cyclogenesis?.... I understand the yellow numbers on yellow line mean Knots? Am i correct? Do I treat the two some what like Highs and lows? (IE Direct of Convergence speeds is Anti clockwize Divergence direction is Clock wize?)

Im Slowly understanding the rest of the stuff but just wanna be sure on this topic?

Regards
The TUNA FISH

I have a question about the tracking of cyclones, in particular, why do cyclones tracking westwards from the Coral Sea almost never pass through the Torres Strait, and even more rarely make it to the south coast of New Guinea except for the south-eastern tip - they almost always cross the coast of Cape York Peninsula or further south. Does this have anything to do with the high mountains of interior New Guinea, or is there some other reason?


[img:left]http://www.bom.gov.au/cgi-bin/silo/cyclones.cgi?region=ause&syear=1906&eyear=2006&loc=0[/img]

I'd like to know the answer to that too Kemu.
I've lived in central and NQ all my life. I had always thought/been told that cyclones that are stationary are more likely to intensify and come in strong than fast moving cyclones - that fast movers loose their intensity, or at least, can't intensify and are less dangerous. Obviously that's not the case...anthony, yasi, larry etc...all moved at a rate of knots and intensified as they did so. Was I the only one fed the old wives tale, or is it more widespread a belief? If so...where did it come from...or, are the previous cyclones the exceptions to the rule?

If you look at BOM's cyclone page, they have a map showing tracks of previous cyclones. There are a couple that have tracked through the Torres Strait, but only a couple.
Cyclones don't form within 500kms of the equator as there is not enough vorticity to create spin- they also have a tendency to track generally polewards once formed.
I hope this makes sense, & I stand to be corrected, but that is my understanding.

yeah ve heard of this tale before. why this doesnt happen because if a cyclone is stationary for prolonged periods of time it stirs up the ocean and upwells cool water from the depths of the ocean and as you know TC's need nice warm water to survive. hence why fast moving/or at least moving at a reasonable speed TC's can generate strength and intensify because there is less upwelling from the water down below. i hope this makes sense

and yes cheekeymonkey, your right with the vorticity thing also remember the TC's spin in the opposite direction in the northern hemishpere....

Thanks, !Schummy, good to know I got that right!

Also interesting to note is that there is never any cyclone activity on the Western side of South America, & only 2 recorded cyclones on the East Coast of the same continent.

There is also no activity off the West coast of Africa, either.

The only explanation I have found to answer why this is that the water temperature off these coasts is relatively low due to the Antarctic streams & the fact that the water is much deeper here. Can anyone confirm/deny or offer another explanation??? (please)

Just found this site that really helped me understand Divergence and Convergence!
http://www.islandnet.com/~see/weather/elements/whatgoesup3.htm

That does make sense, and thank you for taking the time to explain that. Is there any difference between severe TC's and lower cat/TLows though....in that, if a low, or cat 1 is stationary for a while...is that more conducive to further intensification, vs allready strongly formed systems, which gather more energy/power from traversing quickly across warm ocean? Or, is the whole thing I grew up with completely and utterly debunked and I should toss that out of my brain forever?? It seems to be a wide spread belief....unless its just my family! Lol.

a weak system (CAT 1/2) will upwell cold water but itll take longer than the more powerful TC's (CAT 3+). for example....

a CAT 5 that is near stationary/slow moving for 2 days will weaken because it upwells cold water very quickly. A real-life example was STC Ului

a CAT 1 that is stationary/slow moving for 2 days will probably intensify if conditions are right because it takes a lot longer for the cold water to upwell to the surface

hope this helps

Thanks, awesome explanation. (Sorry for late thank you...having trouble staying logged in).

West Africa SST's
Currents pushing cold water northwards means that the warmest waters are around the noirthern coasts of west africa.

South America SST's Yes you are right. Cold antartic currents push too far northwards on either coasts for cyclongensis to occur below the middle of south america.

very interestine SBT i have always wondered about that thanks mate !

Does their season start when ours finishes?

I have no idea. But I would think it would be the same as ours as summer is in the southern hemisphere right now.

i thought Larry was a tropical cyclone not a subtropical one

I have been speaking to others and may have a solution to the current gripes in relation to the CS thread that due to some inflexibility, inappropriate posts and general misunderstandings have led to short term bans and general angst.
I suggest the creation of a cyclone lounge as follows ( the current general lounge is both too far away and too generic)?
Said lounge incorporates the CS, Fiji and Gulf.
When a low, or not, is brewing people interested in extreme weather can chat in the lounge (a similar situ for Darwin, Gulf and WA could mirror).
If it looks promising, or is called, a thread for the said low or TC can be created.
Another tech thread can run along side for said feature.
When said event is over all go back to the lounge (others who wish to continue can do so on existing thread).
This will solve a number of issues, namely:
Members interested in TC’s are essentially homeless when there is no event… solved.
A place where longitude is not an issue….solved
A place for new and old to interact and learn… solved.
A place for the advanced to chat… solved.
A place where mods are not stressed by heavy traffic and silliness when the [censored] hits the fan as there should be no need to make large jumps between threads…. Solved.
This suggestion has received support from some long term members and is seriously being considered by the mods.
However, it may be improved.

Thoughts?

I received an email from the BOM last week saying that the TC name I requested has been put onto a supplementary list. Anyone have an idea how long it usually takes for a name to make it to the main list?

Also if a TC eventuates in Australian waters but doesn't impact on the Australian coastline (eg TC Zelia), does this mean that this TC doesn't actually get retired and it merely gets recycled?

I made an animation of ului's satellite images which show it's deterioration when it became stationary and subsequent reorganisation when it started moving again.
Ului Animation

Sorry for the late reply but I have only just read your post Anundsjo:



Generally if a cyclone has had a significant impact on Australia the name will be retired. In practice most names are not reused so they don't cause confusion. Names submitted by the general public sit on the supplementary list until such times as there is a vacancy for it to be moved onto the main list. Depending how far down the supplementary list your name is it could concievably take upwards of 50 years before it is selected.

http://www.bom.gov.au/cyclone/about/names.shtml



So if we only have 2 cyclones for a couple of years it could take even longer for it to be used.

New website -joint project with Govt/BoM/Greencross. Can find out specific info for your suburb as well. Apparently aimed at all residents but specifically newcomers and young people who have limited local knowledge of their area.
Cyclone preparedness

Dear All (especially newies) ,

I recommend that you check out Andrew's (from BoM) article (published 29/09/11). It explains in layman's terms what will happen during our weak La Nina (which has intensified quite dramatically in the last 2 weeks). It's a bit of OK writing of which I heartily approve. Also - beware of what you wish for ...

When Anthony formed last year I posted I felt in my water there was something really bad out there behind him (felt like a pantomime dame!)... Hello Yasi!

http://www.bom.gov.au/social/2011/09/chalk-cheese-cats-and-dogs/

Och come on people, be realistic this cyclone season! The low in the coral sea, no way it is EVER coming near the coast. Look at the wind shear for heaven's sake. Might bring us some rain in the north. The low in the Arufura sea, now that one could bring us serious rain in QLD. Please be realistic about what you post on this forum. Don't waste our time and your time and get the newies into a feeding frenzy ... just makes everything clog up! Remember CYCLONES CAN KILL, CYCLONES DESTROY PROPERTY, CYCLONES are NOT fun. Interesting to watch, fascinating to follow, but keep realistic posts this year, please.

For visitors who want more information about how, when and where cyclone warnings are issued.



http://www.bom.gov.au/catalogue/warnings/WarningsInformation_TC_Advice.shtml
Introduction
Tropical Cyclone Advices are issued whenever a tropical cyclone is expected to cause winds in excess of 62km/h (gale force) over land in Australia*. A tropical cyclone advice may be a watch and/or a warning, depending on when and where the gales are expected to develop.


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When is a Tropical Cyclone Advice Issued?
A tropical cyclone watch is issued for coastal communities when the onset of gales is expected within 48 hours, but not within 24 hours.
A tropical cyclone warning is issued for coastal communities when the onset of gales is expected within 24 hours, or are already occurring
Each advice issued for a particular cyclone will be numbered sequentially, starting at number 1 for the first advice. A tropical cyclone advice may contain a combined watch and warning, that is it will provide information on the area under watch status and the area under warning status
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How often is a Tropical Cyclone Advice issued?
While the threat remains, a tropical cyclone advice will be issued every six hours, increasing to every three hours when cyclone warnings are required. In some circumstances, when a cyclone approaching the coast is under radar surveillance, the advices may be issued hourly.


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What information is included in the Tropical Cyclone Advice?
Each Tropical Cyclone Advice will consist of the following information:

The area covered by a cyclone watch and area covered by a cyclone warning
The cyclone name
The intensity category of the cyclone (1-weak to 5-strong)
The latest observed location of the cyclone centre
The central pressure of the cyclone (warning only)
The distance of the cyclone to significant locations
The expected or recent movement of the cyclone
Range of destructive winds
Maximum wind gusts
Advisory statements on actions to be taken to mitigate the effects of the cyclone (note this is issued separately for the NT and Kimberley)
The issue time for the next warning
Usually, each advice will have an associated threat map issued.
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Who is the target audience of Tropical Cyclone Advices?
All land based communities in the threat zone.
Note that separate marine warnings will be issued, and all mariners should refer to these warnings for relevant information.


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Where are Tropical Cyclone Advices Issued?
Tropical Cyclone Advices are issued by Regional Offices of the Bureau of Meteorology in Brisbane, Darwin or Perth, depending on the location of the cyclone: