Nice one @mhaberler, sounds like you know your stuff! The Föhn effect is a really tricky beast to forecast; actually, pretty much all mountain-based phenomena in general are a nightmare to get right. As people rely more and more on the models, the forecasters who can actually understand and predict this stuff become a dying breed... But that's a general thing, and for the marjoity of these phenomena, it's only the pilot that will ever see it, not the weather models, and not the observations network. So historical data wouldn't be much help anyway right? But then again, the charts can certainly show you the right conditions for these things to form. If pilots had a medium to add in local scale phenomena that they saw on a flight to a historical chart, that would be pretty cool. That way, they could reference what they saw when that setup reoccurs. I'm getting more and more interested in creating this myself...

By the way, with the aviation briefs, what's the "aviation briefing website"? Could you give me a link? Also, I just spent some time on working on my skewT platform tephigrams.org over the weekend, some vertical profiles, if it helps at all.

Thanks for the comments @mhaberler. You've hit on an important concept here. Is there such a thing as a "historical weather forecast"? You seems to be alluding to model data. The important question is this – could you have avoided a dangerous situation if you had looked at the forecast an hour before flying vs. 3 days before flying? Which model run is the one to reference?

We've talked about creating more detailed surface analyses before. But with an investigation, for example, you would need to know what forecast data you had available at the time (and what's its lead time was). Not only that, but which model. Weather forecast models are an extremely fluid thing, and are just a tool. This is why, when stakes are high, companies shell out for private forecasting companies who employ real forecasters. And with a proper accident investigation, it's usually time to do that. I can't speak to other modelling centres, but I know the UK Met Office archive all their UM forecasts (which cost an obscene amount in storage), so that they can be referenced later.

But, if we're just taking about your own learning, it sounds like a surface analysis would do the job nicely. Surface analyses are traditionally just synoptic charts (isobars and fronts), but I think we can do better. I may just start working on something like that myself (though with one year left, I should probably make a stab at starting to write my PhD thesis).

Let me ask you this @mhaberler, what level of detail would you need to "see if you could have avoided a situation"? Highs and lows? Surface winds? Gusts? Winds at all levels? Precipitation? Visibility? As gridded data or just at airfields? I have some aviation forecasting experience, but we were very focused on just our own airfields, and the WAFC/LOLAN guys used to take care of the rest.

I'd say that understanding the English idiom "all Greek to you" makes you more than qualified to write something @Gkikas-LGPZ!

@garlandz I feel I should mention again (third time this thread!) – I don't work for Windy! This thread is a discussion between users :)

Ah well here's a coincidence @garlandz; looks like the guys at Windy just added this!
https://community.windy.com/topic/8710/windy-predicts-extreme-wind-temperature-and-rain

Hi @garlandz, thanks for the comments. It's a little unclear what you mean. Sounds like you're talking about a climatology, are you not? The "average high" (do you mean temperature?) over a week would be quite different to that of a month, or for a certain month across many years. What are "recent annual trends"? Is that a reference to climate change? Can you give an example of a website that tries to do it? Are you speaking to purely observational data (at airfields), or is there a model component (remember that Windy are primarily focused on model visualization)?

Hey @Coop4433, welcome to the community! Fire weather sounds badass; can you be more specific? I assume you'd be interested in winds at multiple model levels, and maybe some particle dispersion models. Model history of CO2, air quality, aerosol... that sort of thing? Observations?

Hey @StephenBeste, welcome to the world of Windy! Ivo and the team have really created something special here. So, as others have mentioned, the "historical" data you need doesn't go back especially far... And it sounds like you want to understand model performance for your specific location. There's a technique called Model Output Statistics (MOS) that deals with this. Although model verification is a whole science in itself, I've also been interested lately in the idea of creating something like that on a more basic level. Maybe I'll look into it again...

@Franzus-0, of course your post counts! Do bear in mind though, this is merely a discussion; I must reiterate that I don't work for Windy, and I'm not collecting "requests" as such! Congrats on the new vessel, and glad you found your way in the end :) As I understand it, that was one of Ivo's main motivations for Windy; that everyone could have access to the best data possible for free. I was blown away when I saw that they had the full 9km ECMWF fields on discovering Windy; I found myself asking around about Windy at the next ECMWF workshop I was at :) As to the historical data, you seem to be looking for something similar to @rfleming – essentially a type of analysis chart.

Some kind of MOS-based analysis charts that go back a few months, perhaps with some satellite and MADIS data mixed in.... this might have to be my next project :) Thank you so much all for your input. Please keep the discussion going if you have any other perspectives on historical data!

Thanks for the response @4kiting, that's an interesting one too. I like to kiteboard as well and I know how finicky the weather can be when you're looking for the right conditions! It sounds again like a surface analysis is what you want? But perhaps a surface analysis that contains more details, and maybe even spot observations/satellite data mixed in.

@rfleming I should mention, when you say "you guys", I don't work at Windy. I'm just a fellow weather enthusiast :) I had a look at XMWeather though, seems to be mainly satellite data that they do?

I really think there's some potential here for a new way of looking at surface analysis... I'm starting to get the feeling that a big question many people might be asking, when they look for historical data, is: When I look at a pattern in the windy forecast that I've seen before, what does that really mean for me?

I'd love to hear any other opinions.

Thanks for the response @rfleming, that's really interesting :) So it sounds like the kind of historical data you'd want is surface analysis charts? Surface analysis charts are a nice mix of model and observed data, but lack finer-scale detail.

Would you say that it's mainly past model (i.e. gridded data) output that you want, to get a feel for the past weather across an area, or is it more important to be accurate, which would require actual observations (which aren't gridded).