[Closed] Why do weather forecasts vary ?

Just put some polythene up at the windows.

interpretation of data I'd say - it's not an exact science

I don't think Metcheck use the same data as the BBC who use MetOffice data.

They don't all use the same raw data.
They don't all use the same weather models.
They don't all use the same local geographic modelling.

Well, there you go then.
That's answered all my questions.

Watching a program 'The Code' about mathematics and how they influence everything tonight, and weather forecasting was covered, showing how a set of available data was modelled to show the affects of changes over time, then extrapolated over days. After five days it's already becoming chaotic, after ten it's effectively meaningless, the plotted data on a screen is just a scrambled mess. As above, the various met bodies use models that take data from lots of different sources; I believe the Met Office model tends to ignore ocean current and surface temps, which some meteorological experts reckon skew their results somewhat, which is why their predictions over the last several years have been out. I always use WeatherPro on my phone, which is run by Meteogroup, who are German based. I've generally found their forecasts to be pretty accurate, almost to the hour on some occasions.

Because the forecasts are just estimates. Estimates will always vary depending on the source.

Also depends on how you read them. They put a RAIN symbol on a particular day to help people who can't be bothered to try and understand the weather, but what does that mean? It could be a 90% chance of rain all day, or a 30% chance of rain between 10am and 12pm. I've noticed that in publishers who quote the chance of rain percentage the threshold above which they will label a day rainy does vary.

because they don't check with TJ first. He's claimed to have never been caught out by the weather because he can predict it with certainty 😉

It's so they can take it in turns to be right.

I like the fact that they differ as I can just look for the best one.

Predictions of future events in lack of certainty shocker.

There are a couple of German universities and one in Norway that provide feeds to the Met Office here for us. And I think (IIRC) one in New Foundland. But most of the weather patterns we get originate in the Atlantic Tropics and head our way at some point during their cycle, so by assessing satellite images you can get a reasonable view of what’s happening by using the GFS datasets.
But localised stuff.. well you're better off looking out of the window.

Search fro the GFS feeds, that'll give you an idea of whats heading our way (I think these are the German feeds)