Aardvark Daily

Please visit the sponsor!

Chaos, still pretty random

It's now just a few days to Christmas - so what will the weather be like on Christmas Day?

Well I've been watching the predictions of the Met Service and Victoria University's own MetVUW service which, until very recently, were making decidedly different predictions.

These two services obviously use different computer models to generate their forecasts and right up until a day or so ago, MetService was predicting a fine, sunny Christmas Day, while MetVUW was showing the remnants of a tropical cyclone bringing showers to this part of the country.

What does this tell us?

"There's nothing as certain as uncertainty?"

I guess what it really tells us is that, no matter how big or fast your computer, forecasting beyond a few short days is a bit of a lottery.

Although we have very complex mathematical models which often make fairly accurate predictions of the weather, the reality is that the type of chaos which creates weather is still far from predictable beyond a few days at a time.

Faster computers won't help much -- if the model is insufficiently accurate and these models are still far from perfect. In fact, I doubt they'll ever be perfect until we reach a stage where every molecule of the earth and its atmosphere can be represented. Even then however, we'd still have to make assumptions regarding the exact levels of solar intensity -- something which also changes on a day-to-day basis.

Watching these two models gradually resolve on the now agreed forecast of rain for December 25 in Tokoroa, it is obvious that they are wildly different in the way they perform their predictions. The fact that they are so wildly divergent at times also shows how far we have to go before we get some really reliable forecasting beyond 2-3 days, especially when there are wildcards such as tropical cyclones involved.

It would be interesting to see just what effect the introduction of bigger, faster computers has had on the accuracy and reliability of forecasting. Surely someone's done that analysis -- yet we don't see it being publicised. Why?

Regardless of their general accuracy, one thing is for sure -- it might be a good idea to batten down your hatches this weekend if you live in the North Island. Sunday's looking a bit rough!

Please visit the sponsor!

Have your say on this...

PERMALINK to this column

Oh, and don't forget today's sci/tech news headlines

Rank This Aardvark Page

Change Font