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Time to ignore the forecast!

Posted: 5 Jun 2019, 11:17am
by gbnz
Just had a wasted fortnight, as I carefully avoided having a ride down in the Dales, the Lakes and various other outdoor stuff, purely on the grounds of the detailed and invariably grossly misleading forecasts by the Met office. And as day, after day of fine weather materialized, the afternoons of heavy rain turning into a single brief few spots of rain (NB. Not even sufficient to bother putting the coat on), I believe I may have learnt my lesson!

Just "go and do it"! Believe I'll be heading off on that Dales/Lakes ride in the next few days, the met office predicting rain :shock: (NB. Until 10 minutes before the rains due to commence, at which stage the met office will change its' forecast to one of fine weather)

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 11:34am
by slowster
It does seem to me that the Met Office forecasts have some bias which means that it is much more likely that the forecasts predict rain which does not materialise, than that the forecasts do not predict rain only for rain to fall.

I think most people will be more likely to take note of a failure to predict rain, e.g. because it spoils their day/they get wet, than to take note of a prediction of rain that does not occur. Because people will therefore be likely to be far more critical of the forecasts in the former case, I think the Met Office modelling is biased towards predicting rain.

Consequently I'm increasingly inclined to think that it's often best to ignore a forecast which only predicts a very short spell of rain: there's a good chance it will never happen, or rather that you will not get caught because the shower falls 10 miles away instead.

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 11:35am
by philvantwo
Use the Mick F recommended app called 'windy' It's loads better!

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 11:47am
by thirdcrank
Michael Fish has a lot to answer for.

https://www.youtube.com/watch?v=uqs1YXfdtGE

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 12:51pm
by mjr
None of them can forecast the specifics anyway. They start off with low accuracy for the first few hours forecast and accuracy then falls!

Take waterproofs and sunblock and you'll be OK unless there's something truly apocalyptic forecast, in which case it's probably worth noting shelter locations and possible escape/recovery routes.

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 1:46pm
by mattheus
slowster wrote:I think most people will be more likely to take note of a failure to predict rain, e.g. because it spoils their day/they get wet, than to take note of a prediction of rain that does not occur. Because people will therefore be likely to be far more critical of the forecasts in the former case, I think the Met Office modelling is biased towards predicting rain.

I thnk that's dead right. We [Brits] only have ourselves to blame, for all the whining over the years about crap forecasting - ina country with one of the least predictable atmospheres on the planet.

If I were a forecaster, *I* would err on the pessimistic side too!

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 4:34pm
by nirakaro
I heard of someone who wrote a piece of software to check the 5-day forecast, and compare it with a random guess. He found that the random guess was right 30% of the time, and the forecast was right 35% of the time.
I also heard of a lawyer who found an old and unrepealed law dating back to Puritan times, that proscribed fortune-telling and 'attempts to foretell the future'; I think he failed in his attempt to have the Met. Office prosecuted under it.

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 10:04pm
by drossall
slowster wrote:I think most people will be more likely to take note of a failure to predict rain, e.g. because it spoils their day/they get wet, than to take note of a prediction of rain that does not occur. Because people will therefore be likely to be far more critical of the forecasts in the former case, I think the Met Office modelling is biased towards predicting rain.

I've come to that conclusion too.

Re: Time to ignore the forecast!

Posted: 5 Jun 2019, 10:10pm
by Mike Sales
drossall wrote:
slowster wrote:I think most people will be more likely to take note of a failure to predict rain, e.g. because it spoils their day/they get wet, than to take note of a prediction of rain that does not occur. Because people will therefore be likely to be far more critical of the forecasts in the former case, I think the Met Office modelling is biased towards predicting rain.

I've come to that conclusion too.


I have come to a similar conclusion about the shipping forecast. Underforecasting the wind strength will possibly have serious consequences. Forecasting a wind stronger than the one which blows is not a problem. However, I would not make the decision to sail on that basis.

Re: Time to ignore the forecast!

Posted: 6 Jun 2019, 6:52am
by Oldjohnw
There's possibly something slightly silly about blaming anyone other than the Almighty for the Bristish weather. We are on a tiny island(s) between the Atlantic and the North Sea. Nothing should ever surprise us. There is always a caveat.

Re: Time to ignore the forecast!

Posted: 6 Jun 2019, 7:28am
by francovendee
My method is, plan to go, look at the forecast, look out of the window and decide. I have been caught out but not often.

Re: Time to ignore the forecast!

Posted: 6 Jun 2019, 8:01am
by Mick F
francovendee wrote:My method is, plan to go, look at the forecast, look out of the window and decide. I have been caught out but not often.
Spot on!

Looking at the weather forecast this morning because Mrs Mick F is off to Royal Cornwall Show today. She wanted to know what to wear.

Met Office was very pessimistic and BBC Weather was slightly optimistic. Metcheck was half way between the two.
I don't care if they're right or wrong, but they all should sing off the same hymn sheet?
Maybe they use different algorithms and observations, so as they don't all agree, it means none of their algorithms and observations is worth a pinch of salt.

I like looking at the weather radar sites. You can see the rain coming ......... live!

Re: Time to ignore the forecast!

Posted: 6 Jun 2019, 8:05am
by gbnz
Mick F wrote:
francovendee wrote: look out of the window salt.

I like looking at the weather radar sites. You can see the rain coming ......... live!


Even more true of looking out of the window :wink: And have to admit I'm rarely wrong, quite unlike the met office.

Should I be scared about the heavy rain and gale force winds which will be affecting me throughout my coming "weekend" tour? I think not, as I cycle along under blue skies, sun shining and notice the single puddle left by the rain and the leaf blown off a tree by the notional gales

Re: Time to ignore the forecast!

Posted: 6 Jun 2019, 8:05am
by John1054
When I lived in Cumbria, we always used the adage "if you don't like the weather, wait an hour, then it will change". Mind it might not be the change required!

Also found our barometer was many times more accurate than the forecast. Just ride became the best motto. :D

Re: Time to ignore the forecast!

Posted: 6 Jun 2019, 8:07am
by gbnz
John1054 wrote: Just ride became the best motto. :D


Exactly the approach I'm taking. Booked the train tickets yesterday, despite the coming heavy rain and gales!