The Australian Bureau of Meteorology southern hemisphere forecast.

The BoM do a splendid long range sea level forecast.

It relies completely on satellite imagery and is virtually unmanaged by human hands.

This makes it ideal for following with the possibilities for adapting the errors of so called Butterfly Effect into reasons why numerical data analysis can go wrong.

The reasons data analysis can go wrong are covered in Wikipedia’s essays on the butterfly effect. I am going to assume that you have read the essay and understood the basic concepts. (That it has nothing to do with butterflies on the other side of the planet flapping their wings and bringing your house down on you in your sleep.)

Before you start trying to understand a chart, you have to be aware of yourself and the weather around you. It also helps if you are settled and relatively stress free. If you are a religious person getting straight with your god will definitely help. But just having a decent night’s sleep and a wash and a warm cup of tea before you start will do wonders.

You also need to be aware of how distant weather affects you.


In Britain we have weather that is hair triggered to affect us all the time, almost every day because it changes so rapidly. I believe any maritime climate will do that but I have very limited experience. A lot of people would enjoy the weather a lot more if only they got out more often and didn’t sacrifice their free time to watching television. Other problems lie in the fact that in some countries finding work outside all day long is almost impossible.

And finally as a matter of health you define a good day as one which doesn’t cause your body’s nervous system to react in a way you can’t quite understand. For most people, getting old means ab-reactions to certain weather. But it is never quite the same weather as caused the problems last time. And not knowing what causes the problems having tried everything to the point of hypochondria, most of us do the sensible thing and give up, relying on drugs and fortitude to help us through periods of intense pain.



Your mileage WILL vary. Everywhere reacts to the planet’s reactions to the solar system in different ways. It is fairly obvious that maritime weather is going to be different to continental weather. And even continental weather in one hemisphere will differ from that of another hemisphere. Polar weather changes with a day that last for 4 or 5 months and has only a few actual days to the year. most of them occurring around equinox.

I am assuming you know what equinox is; also solstice. We don’t have to be experts on Stone Henge, just au fait with a basic Earth Science glossary. But if you know how to interpret a Nautical Almanac you are most of the way to being a pretty good interpreter of the weather. (To start with you will be capable of making interpolations and applying the idea behind such second guesses to other concepts which will crop up from time to time in reading any weather chart, more especially if it is a weather chart for half a planet (and the wrong half of it for your location at that.))


If you want to find out more about Stone Henge, there are plenty of books on the subject. Beware of some of the idea trolled out online. Fred Hoyle wrote a good one about the place though he failed to appreciate it’s daily importance; considering only the path of the sun. I dare say Wikipedia may have as much and more on that. It isn’t absolutely necessary to have that under your belt but if you could work out how to set up a sundial locally or find suitable alternatives such as chimneys and aerials, trees and lam-posts viewed between the sun and you from a suitable window or wherever, you could follow some of the esoteric things a little more easily.


None of any of the above is necessary to get a lot of information out of the BoM chart here:

The default is for Australian time. I have my browser open it as Greenwich mean time (UTC)

The charts run in 6 hour sequences the first chart dropping off the chart so to speak every 6 hours. As far as I know, the first chart is still a forecast chart. Most meteorological agencies process the first chart directly from available data, which in the northern hemisphere is quite extensive. Those presentations generally start with an Analysis Chart. That is one that has had a whole team of meteorologists running sequences of dta time and time again until the head meteorologist is satisfied that he can’t do any better.

The finished product is then put through them mincer and run out to several days until stupid o’clock. The subsequent charts are thus forecast from the analysis ones and contain all the floating point mathematical errors and the uncertainty principles of Butterfly Effect. (Subsequent model runs are made over and over again on computers so large that they consume unbelievable amounts of energy. One story I heard is that it takes a small power station’s output to do a full run every shift. I still find it hard to believe that the electricity consumed is the same as that of a small city.)

I am going to show you what the BoM chart looked like on the 27th of November 2013. If you are reading this you can still grab the remnants of the show from the site and store it for future reference so you can see how it all pans out. I will post an animation of it in a follow up. But it is time for me to go to work now and I can’t post much more than the above in an introduction, can I?


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