BBC TV weather forecasts - just ignore them !!

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BlueSkyNick

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I have been saying this for years but am now sitting at home when I could be halfway to Weymouth this morning. I should have stuck to my plan based on my forecast models of choice - windguru, predictwind and ugrib.

Cut a huge long story short, SWMBO and I have been planning 4 days (Wed to Sat) aboard, going somewhere, relaxing, etc Really fancied Alderney or Chichester in the right conditions, but anywhere away from the Solent would be good.

Wednesday was aborted because neither of us wanted to spend Thursday sitting in a boat in the peeing rain, we had enough of that back in June, so the dog didnt get taken to kennels. Then Wednesday afternoon, I made a plan for Thursday morning for me to catch the start of the ebb, in light rain which was going to clear and I could tolerate. SWMBO was to put the dog in kennels then take the train to meet me in either Poole or Weymouth.

Last thing before I went to bed last night, the lady on the television said its going to rain pretty hard for most of the day so I cried off and opted for a lie-in.

Now today, it is SE4 (ideal for a broad reach, single handed) a bit grey but not raining at all so I should have gone and had a good sail ...... ARRRGGGHH!

I keep telling people that the forecast on the TV is very generic aimed the vast majority of the population, and who don't care about the combination of rain, wind and tide.

Having ignored my own advice, a whole trip has gone by the board - looks a night in Cowes again :(
 
Well its been like the monsoon in Devon all morning!

The dingy is in the back of the car and we are considering taking it out and seeing if we can float it in the car park at lunchtime, any deeper and I'll be adding the outboard :D
 
Its been like that all year in Felixstowe - met office/etc havnt got a clue..lost count of how many days sailing we have lost through not following our instincts...plus its so localised ....one day in July we couldnt even see our boat from the shore (about 100 yards) due to thick fog - not predicted and no evidence of it at home (5 minutes away!) Then in August we delayed the start of our passage because of predicted high winds, only to find they never materilised and the following 2 days there was NO wind!!
 
moodyNick said:
I have been saying this for years but am now sitting at home when I could be halfway to Weymouth this morning. I should have stuck to my plan based on my forecast models of choice - windguru, predictwind and ugrib.
Click to expand...

I've not heard of "predictwind" but windguru and ugrib aren't "models". They are, like most of the internet sites, just pretty ways of showing the free GFS output. I've been watching the GFS forecast (via XCWeather, my chosen display) for this weekend with possibilities of going windsurfing, going for a sail in an open boat, or doing some gardening. The forecast has been up and down like the proverbial lady's drawers. Obviously I'd like to slag off the BBC or Metoffice as they are by the gumment spending my taxes etc., but I'll have to slag off the commercial/USA one instead. Or maybe I'll just understand that forecasts are sometimes reliable and other times less so.
 
I well remember Carol Kirkwood saying we will have weend and reen all day on the day that England won the Ashes...

In the evening the big news story was the party in Traff Square with people dancing in the fountains in the heat and sunshine...

I do suspect that she concentrates on reen and dreech and lots of weend because it rains a lot in the part of the world she hails from...
 
Nico said:
I've not heard of "predictwind" but windguru and ugrib aren't "models". They are, like most of the internet sites, just pretty ways of showing the free GFS output. I've been watching the GFS forecast (via XCWeather, my chosen display) for this weekend with possibilities of going windsurfing, going for a sail in an open boat, or doing some gardening. The forecast has been up and down like the proverbial lady's drawers. Obviously I'd like to slag off the BBC or Metoffice as they are by the gumment spending my taxes etc., but I'll have to slag off the commercial/USA one instead. Or maybe I'll just understand that forecasts are sometimes reliable and other times less so.
Click to expand...

Sorry, I obviously didnt explain myself very well, and used wrong terminology.

windguru and predictwind (which is a subscription service) present the information in far greater detail for specific audiences in small areas.

The BBC present a forecast in about 60 seconds to cover 60 million people. SO it is very generic in that it "there will be rain in the southwest" could cover anything from Southampton up to Oxford and across to Bristol. Hence it is less accurate for more people, and more open to criticism.

I disagree that the different websites are just pretty displays - they do apply some interpretation to the data in creating the representation on their websites, and there will be variances between each one. XCweather is an interesting one in that it is relatively easy to understand, but is rarely correct in my experience - I wouldnt make a decision to sail or not, based on XCW.

Predictwind takes input from GFS and the canadian service CMC and provides both sets of data. They can be quite different 5 days out, then tend to align as the forecast period reduces. This has the benefit that you can compare the two and make a judgement. For about £20 pa its good value, IMO.
 
Tomahawk said:
I well remember Carol Kirkwood saying we will have weend and reen all day on the day that England won the Ashes...

In the evening the big news story was the party in Traff Square with people dancing in the fountains in the heat and sunshine...

I do suspect that she concentrates on reen and dreech and lots of weend because it rains a lot in the part of the world she hails from...
Click to expand...

...nice to look at for an old bird though...... :D
 
FWIW I find the Met Office Inshore Forecast too pessimistic, XC Weather too optimistic and Windguru somewhere in between. I look at all three plus the BBC and Met Office general forecast for the area and then make my own mind up.

This year, it seems like almost every weekend had a Met Office Inshore forecast showing a Strong Wind Warning! The other thing that bugs me is when they forecast "F2 to F4 perhaps rising to F7." Yup I suppose is likely to one of em.
 
It is perhaps a bit unfair to have a go at the BBC as they are only the medium and not the forecaster.
A while back I enjoyed the company for a week on board of one of the BBC weather presenters, in fact an employee of the Met Office on secondment. As per normal each morning we listened to the CG forecast as provided by the MO and each evening compared the forecast to the actuality. It was only after day 3 that we had to stop embarrassing the young (and delightful) lady about their inaccuracy. Our explanation was that she was with us and not doing her job, and that someone else was getting it wrong! Notwithstanding, it was an interesting week learning a lot more about weather from a meteorologist, and how the forecasts were arrived at, for myself and the rest of the crew, and from a forecasters point of view, what it's like to be on the wrong end of an inaccurate forecast (although the forecast was probably right for somewhere 10 miles to the north).
 
There is not a great difference in the various models. The main ones are the GFS, ECMWF, UK Met Office. At 5 days ahead the ECMWF should be slightly better than the others but there is little in it. Differences in forecasts is more likely due to differences in the analysis of the input data. These are many and varied. These major centres have put and are continuing to put a vast amount of effort into the pre-processing to start off the forecast. They use a form of 4D analysis but there are always uncertainties. There is a vast amount of data from satellites, accurate in what they measure, but which does not give a uniquely correct detailed analysis. There are a much smaller number of in situ data, far more precise. The combining of these is far from being an exact science.

When I last asked them, it was clear that none of the private modellers was using anything else other than the GFS 0.5 degree data (or CMC) to start off their models. The models are OK. I just have doubts about the quality of the data input. Does anyone know more about this?

It is for these reasons that these centres run model ensembles. The forecasters on TV have the ensembles output available to them. They discuss these with the chief forecaster at Exeter and agree on how to interpret them

For some reasons, this year seems to have been extraordinarily difficult. We were sailing for 5 months around western France and it was more difficult than normal to plan ahead. The GFS was very inconsistent. I did not find ECMWF any better nor the UK synoptic charts. The days 4 and 5 of these are produced after studying output from both the UK and the other centres.

The UK Inshore waters and shipping forecast often appear to over forecast winds. This relates to the rules for gale warnings. If there is doubt about gales in the immediate or soon category, then the forecast may say "perhaps locally" or some such phrase, BUT a warning MUST be issued, On the other hand a gale warning is only cancelled or allowed to time expire if the forecaster can say, “Gales have ceased..” A cancellation is a statement of fact. A gale warning is a forecast.

XCWeather is the GFS. Inevitably it and, I guess any other computer model will usually under-estimate the stronger winds. Perhaps more correctly, the average may not be too bad but there will always be variations that are below model resolution. . Wind is a very noisy signal. A rule of thumb is to add one Beaufort force to GRIB winds.
 
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