[rdtsc]

> So.....saying we can make as accurate of forecasts for 200 years ago...that's not really saying much.

It is saying quite a lot actually because the past has already happened. In the first case you are talking about the future, and yes, in some places weather is more unpredictable. You can of course move to the desert and enjoy clockwork predictable weather if it bothers you that much.

The OP was talking about "afcasting" though. In that case measurement have already been taken, but there are other records: ice cores, sea sediment, and many others. So it makes for a very interesting topic.

[rnovak]

wait a second. The OP was comparing "aftcasting" TO "forecasting" 2-3 days in advance, and that's what my statement was based on.

If your 2-3 day forecasting is off by 5-6 degrees (celcius), why would your "aftcasting" forecast for 200 years ago be any more accurate if it is "just as good" as a 2-3 day forecast? That means I would expect an error of 5-6 degrees, same as a 2-3 day forecast

edit: formatting

[cryptoz]

If everyone is nitpicking that part of my comment, it would be worth noting that I was paraphrasing from the paper I linked.

> For the beginning of the twentieth century, the errors of such upper-air circulation maps over the Northern Hemisphere in winter would be comparable to the 2–3-day errors of modern weather forecasts.

Might be worth reading the abstract / full paper if you're interested in the topic.

[rnovak]

what's the actual error bound on both forecasts and aftcasts?

The article this discussion is linked to is claiming "1.46°F (0.81°C)" variance over recorded history. Recorded meaning they know what actually happened.

But I cannot believe that 2-3 day forecasts are accurate to within 2 degrees. Even the services linked by other commenters criticizing my original point claimed only 77% accuracy in the best case,