Several satellites take high resolution real time pictures of global weather they run 24 x 7 for years and that's RAW data.  There are several of these plus radar stations etc.  NOAA uses a subset of that information to make weather forecast (they normally toss out old data and data from the other side of the planet because it's not useful even if it might make a slightly better forecast).  We can make highly accurate block by block forecast an hour ahead over major cities and just about any point in the US.  However, there is little point in reading that level of detail from a forecast for such a short period of time.  Sometimes when the forecast is 50% chance of rain over the next 8 - 12 hours they know where and when it's going to rain they just don't know where you are.<p>edit: <i>One of the world's largest scientific data systems, NASA's Earth observing system data and information system (EOSDIS) has stored over three petabytes of earth science data in a geographically distributed mass storage system.</i> that's just Nasa and a lot of their data does not make it into EOSDIS.<p>The goal of science is to understand the world.  Running the same simulation on the same data and getting the same result only tells you that the machine running the simulation is not broken.  What you want is to run a different program with different assumptions on different data and come to the same conclusion.  This is actually used to make 7 day forecasts.  They run a few different models with different assumptions and pick the average result.  Over time each model is updated independently to maintain its independence.<p>PS:  You don’t validate E=MC^2 by doing the exact same experiment 10,000 times.  You do every type of experiment that you can think of which relates to E=MC^2 looking for anything which does not work out the way you think it should.