Why can meteorologists give a clear weather forecast up to about 2 weeks, but not for example 3 months?

Meteorologists could make weather forecasts for many weeks, months if the information available on local weather would be better known at any place on Earth.This information is not available and is used in practice with many thousands of weather stations and satellite recordings. For the remainder, averages are taken between the different measuring points. This gives a chance of small measurement errors in short-term weather forecasts. In the longer term, small measurement errors can grow into large effects. Also, the computer models struggle to make good predictions for complex landscapes like in the mountain regions where air currents are difficult to calculate. In practice, computer models use a worldwide “grid” of simulation points of about a few kilometers in surface area.

For longer periods, meteorologists can calculate global trends (on the scale of climate change), but do not make predictions on a local scale (it will rain on May 3, 2024 in Maastricht).

Future is a state with more entropy (chaos).This makes the future unpredictable. At most, you can create a probability calculation for the possible outcomes. The further you look in the future the more possible scenarios exist and the more inaccurate a probability calculation becomes.

Weather forecasters do nothing but present the most likely scenarios to you.For example, there is 60% chance of unstable and cold weather and 30% chance of sunny and warm weather. The farther you look forward, the more ans there comes on different scenarios.

Because of the instability of the atmosphere, especially in the North Sea area.The calculation models used for the weather forecast are particularly susceptible to minor inaccuracies in the initial values. These are determined by measuring data (wind speed and direction, air pressure, humidity, temperature and a few more things) and the measuring grid is not bijzinder fine-grained (typical distance between two measuring points is 100 km). So there’s still some uncertainty and it’s already a whole feat if it’s a bit accurate within a week. Sometimes a predicted bui falls 50 km more northwards or eastwards. The people who get wet find that the prediction is not right, but in the higher sense the prediction is just a little out of the lead. But of course you won’t get any less wet.

In areas with a stable atmosphere (for example, the Sahara), the time limit for predictions is much longer.

There are too many uncertainties that are increasing over time.Depends on which areas a weather forecast is being done. For the Atacama desert, a weather forecast can be made with a great certainty that the first six months will be no precipitation.

Weather forecasts of up to five days are relatively accurate nowadays.From then on it goes downhill pretty fast.

Two weeks is barely more than coffee grounds look.

And how is that?Because there are many different factors that affect the weather and measure all those influences and incorporate them in the intent is impossible. We’ll get better at it, but it’s not perfect for a long time.

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