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.