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Statistical Accuracy of Internet Weather Forecasts
markmcb writes "Brandon Hansen considers the statistical accuracy of popular on-line weather forecast sources and shows who's on target, and on who you probably shouldn't rely. Motivated by a trip to a water park that was spoiled with hail despite a 'clear sky' forecast, he does a nice job of depicting deviations, averages, and overall accuracy in a manner that stats junkies are sure to love."
What a nice piece of work.
I can't help but smile a bit that MSN weather in this test turns out to be the absolutely worst when it comes to accuracy in almost all categories.
I would think there is a lot of difference on how the forecasts are made in the different channels, some of them probably do get a lot of their information from meteorologist working on their own stations. I wouldn't wonder if MSN doesn't have a meteorologist (or maybe only one) working to provide their forecasts.
Computers and simulations play a big role in predicting the weather today, but human eyes are worth a lot still.
I don't myself live in the USA, so my primary use of these are to check on when there is severe weather in areas where I know someone.
I have gotten used to check on weather underground for this information, I haven't checked on many other weather channel, but I feel quite well capable of following what is going on in the USA with tornadoes and such here from Denmark.
For a long time we only had one weather forecast service here in Denmark, a national institute. Since a primarily private TV station (TV2) a few years ago started their own weather forecast service, I really feel the national institute have been pulling themselves together and have provided many services that they didn't provide until now. So even though some of the services provides terrible accuracy they might still serve a good purpose in giving the other services competition and thereby forcing them to improve also.
When I am really dependent on the forecast I tend to study the information behind the simple prediction of the given weather, that way I am also much better prepared for possible scenarios, knowing which front move where and can better "read the skies".
I use the NWS website, mostly because I hate all the annoying flash ads on most of the other sites. I was also under the impression that most of these sites get their information from the NWS and pass it along to you (along with a bucket of ads). There was a lot of complaining amongst the popular weather sites when the NWS opened its own web site.
"Can't you see that everyone is buying station wagons?"
I remember some years ago a radio presenter saying that you could achieve greater accuracy than supposed weather forcasters simply by using the assertion: today's weather will be the same as yesterday. Have we moved on from this position?
Any sufficiently advanced bug is indistinguishable from a feature.
I am not a meteorologist, but I have worked with them a few times.
Generally the competing weather models will show a range of possible outcomes with various probabilities. You can average across all scenarios and come up with a 60% probability of rain, but the more days out you go more the scenarios diverge, so the less useful a single average will be.
Most people would not find it useful to hear that "there will be probably be thunder on Wednesday if it remains hot enough, but if it cools down on Tuesday then the thunderstorm will be off to the north somewhere"
Additionally, a lot of weather conditions are influenced by thin layers of cloud high up, so thin that precise measurements are critical so precise forecasts in one location more than 3 days out are difficult.