indyfabz

+1.

And what KIND of rain? SCATTERED showers? And WHAT TIME of day?

I live on the east coast, where many people are not as "tough" when it comes to weather. When I led club rides, many times people would not show up because they would look at some on-line weather site or look at the news, see some cloud/rain drop icon and .worry that they were going to get wet when really, had they taken time to dig down, they would have seen something like a relatively low chance of scattered, light showers occurring at a time when the ride was likely to be over.

indyfabz

Huh?

How does the site entice me to visit by purposefully overestimating the chance of rail if I first have to go to the cite in order to see the overestimation? If I hear from a different source (e.g., TV news) that bad weather is approaching and THEN go to the site, it isn't the site that attracted me. And since I am already at the site, there is no need to overestimate anything to attract me to the site. Finally, overall site traffic would likely decrease over time due to purposeful inaccuracies.

Seems you didn't think this one through.

noimagination

But ... that's what a FORECAST is. It is a prediction. And a prediction isn't very helpful if it doesn't give you an idea of its accuracy.

A 70% chance of rain means that 7 times out of 10 it will rain, and 3 times out of 10 it won't. If, over time, the model's accuracy is different from the predicted accuracy (let's say there's an improvement in the model, or in the measurements that go into the model, or some other change), then the accuracy in similar circumstances can be changed, say a forecast based on a set of data and a prediction model used to give a 70% accurate forecast, and now the accuracy is predicted to be 75%.

Unless you have a crystal ball, or a time machine, no non-trivial prediction will be 100% accurate. Even a prediction that the sun will rise tomorrow will eventually fail.

FBinNY 

There might be a bias to saying rain based on how people respond when they're wrong.

People get mad when it rains after a fair weather prediction, but are more likely to forgive if it doesn't rain. Also, consider that they forecast for a general area, but rain can often me more localized. So if it's goin to rain anywhere in the area, that's a rain prediction, or at least "scattered showers", but it might not rain on you.

As a cyclist, I'm used to this, and have often ridden for miles on newly wet roads, while not seeing rain. OTOH I've often ridden in rain for hours, when all I needed to do is stop and let it pass.

I take forecasts as a rough guide, but prefer to look at the radar map before riding, then read the clouds and wind once I'm out on the road.

daihard 

I know what you're saying. it's just mighty frustrating when a high probability of rain (e.g. 70 percent) turns into no rain more than once in a week.

Unfortunately, that's not how probability works. A 70 percent chance of rain on a given day does not mean it will rain 7 out of 10 such days. You can think of a baseball player who has a 0.25 batting average. It does not mean they get one hit every four at-bats. It simply means they have a 25 percent chance of getting a hit in each at-bat.

noimagination

Umm, what?

That's exactly what it means. One hit every four at bats, as your N approaches infinity, is exactly the same as a 25% chance of getting a hit over a large number of results.

Saying that it's frustrating that twice in one week a "high" probability of rain resulted actually in no rain, while it may be true, is about as reasonable as getting frustrated that you get a coin flip that results in 4 heads in a row when you're betting on tails. Or that your 0.250 hitter gets 3 hits in 4 at-bats against your home team. That's how probability works. Probability applies over a large number of results, there nothing in probability that says that you can't get a different probability if you restrict your sample to a smaller number of results. What if you based your calculation of "probability" of a coin-flip on 3 results? Or 4, or some other small number?

Trakhak

The same shaky grasp of probabilities shows up every time someone complains about getting a string of flat tires. "I went six months without a flat, and then got four in two months!" Setting aside factors such as road conditions, monthly mileage, etc., the chances are fairly low that your flats will arrive at symmetrically spaced, equal time intervals.

daihard 

Yes, if a batter with a 0.25 batting avegae bats N times, and as N approaches infinity, then they are likely to get a hit (0.25 x N) times. That doesn't translate into one hit in 4 at-bats. They may very well get 4 hits in 4 at-bats in one ballgame, and none in the next.

genejockey 

Boy howdy! I had real difficulty getting my MIL to believe that playing the same numbers every time in the Lottery did not incrementally increase her chance of winning every time she lost. And the brain rebels against the idea that "1, 2, 3, 4, 5, 6" has the same chance of winning as any other 6 numbers. It wants to think "random" = "evenly distributed"

WRT flats, mine cluster in September and October, because that's when, after no rain since April and baking in the sun for months, the sandstone beside the roads I ride starts breaking up and the rocks roll onto the bike lane, and I am a pothole and rock magnet.

genejockey 

But as N approaches infinity, the batter is getting older, his reflexes aren't so good, and he starts missing them more often....

genejockey 

Oh, WRT the original topic - this year I learned that a 9% chance of rain is not the same as 0% chance of rain. Also, 40% isn't 100%. So anything above about 5-10%, I prepare as if it might rain, and I don't call off the ride for anything lower than about 70%.

daihard 

So true...

indyfabz

Followed by the sunscreen poll thread.

shelbyfv

Che begat grantelmwood begat bikelif3....

bikelif3

I think "minimally related to cycling" means "I can't make money from it".

Polaris OBark

Are you getting paid to pollute bike forums?

bikelif3

I WISH...

How are you being paid??

rsbob 

Better to over predict inclement weather than the converse. In that way people are prepared if it does arrive and please when it doesn’t. Don’t see it as click bait unless they are throwing adds at you.

veganbikes

"Your mother, Trebek" - Sean Connery

bikelif3

veganbikes

Spliced quotes. Didn't hit the mark..

Polaris OBark

Your mother.

bikelif3

My mom is DEAD. Ok, not really, but I just said that to make you sound like you sounded in your post....

Polaris OBark

TwoChe

Polaris OBark

4Lif3

bikelif3

whateva...whateva...