Why XCweather & WindGuri are so inaccurate

[weathercam]

Ok for those of you that know my various rants you know that one thing that gets to me is people praising the likes of XC and Windguru - well now I'm back at my original seafront loaction with the dogs bollox of a weather station, over the past week I've been looking at both XC and Windguru and to say that they are soooooooo inaccurate is and understatement - OK I'M ONLY TALKING ABOUT SHOREHAM / WORTHING here, but let's face it that is where it matters most - we tend to give our cast off's either downwind to Camber and the like or upwind to Wittering (that'll be ten pounds so) or to Hayling where they'll have at least a force less than here - but I'm digressing....

 

XC currently, apart from not even reporting on Shoreham has been giving 13 -15mph for our area - and that's actual wind speed - where as the actual highest gust so far had been 28mph at 07:13, with wind at 20 -25mph - the readings for the past week have been consistently under reporting - and as for Windguru forecasts, I think if you had relied on that, then you would have hardly made it out on the water - why ----> because at this time of year they do allow for "thermal" top up's that is sea breeze acceleration and what goes with that - change in wind direction from NW to SW..........

 

And as I've said before, XC takes its data from the airports, this data is often a couple of hours out, and XC time stamps it as "current" - most airports are built in the wind shadow / lee of the prevailing winds for obvious reasons so the their weather stations will often be reporting less than actual - prior to me reinstalling the weather station back in its current location, I had it uploading from East Preston, where the station was situated only some 250mts inland, but behind some houses / trees etc and on average the wind speed was at least 7mph down - that's why I had to use the high wind speed graphs as the actual.

 

So there you have it - have I earned my plug now....so for weather updating every minute and with a live streaming cam - see http://www.seaspritesports.com/weather/weather.htm - plus when the winds light at from the N / NW direction Shoreham will not report true wind speed due to the position of their station - so as we know Chimet over reads and Phils new station is sooo much better at Hayling - now probably you'll believe me!!!!!!!!

[gillstah]

that's great stuff WC. fancy moving to newcastle? (or tynemouth even).

 

i also find them inaccurate and rely on a quick drive by the beach with the 'blue flag' flag to determine whether it's worth going out.

[cave_raver]

I see your point and I too have been frustrated but down in the SW it's all we've got. I tend to use a mixture of the Met office inshore waters forecast which is mostly accurate, the two you mentioned and then web cams nearest the place I want to be. As for the BBC, well it's pretty poor and so general on wind that I don't even give it a glance. I also use www.weather.co.uk which is pretty good.

 

CR

[QUOTH]

yesterday it was predicted 8mph+ at ainsdale. nothing, as in nout. no wind

 

dont know how accurate it is most of teh time though

[spooky]

The problem with ALL weather sites tends to be two areas, one how up to date teh info is, xcweather shows what time the readings were taken but up dates tend to be every 1-2 hours? But it does give the last 3 readings so you can see if there is a trend developing, ie increasing slowly or constant etc. The other problem is it does not take into account teh terrain, most airports are in big open areas so you will tend to get a reading fo rthat area, where as your location say 5 miles away may be different due to hills up wind reducing the wind or in a valley casuing the wind to acclerate etc?

At the end of the day use it as a guide and then add your experince to it, ie if it is showing 12 from the west and you know that when it does that due to the terrain locally you acctually get 17 or shows 12 but from the NE you get only 9 then you will soon build up a metal picture/file of your best flying sites/conditions.

After all it is very dificult to predict something that has so many veriables? If it was easyto do so we woudl all be Millionaires

Fly safe, Jon

[carlesma]

I'm in full aggreement about xcweather at the mo because when i left mine last night to go to shoebury east beach it said 12 mph but this must have kind of died as by the time i got there (10 mins) i could barley gat the kite in the air, there was one other kite up (only just) i think it was chris (duck designs) but its not the end of the world i suppose as the pub was open so i just went there and got the consalation prize.

[Mr Jo Macdonald]

In Italy I find Windguru pretty acurate in the winter and for summer squalls but it doesn't seem to consider or indicate thermals so if you know there should be a thermal you can add that on to the indicated wind if it's in the same direction

[8015]

Only tried windguru a few times and it was always way out.

 

XCweather output varies, most annoyingly when I most want to know the updates seem to be delayed by a couple of hours but at other times are quite recent. The site I use mainly is Prestwick airport, the beaches I go to are up to about 5 miles maybe a bit more to the north of Prestwick on a large curving bay with not much in the way of hills directly inland to the east. Which means that when the winds are in the west, which makes the beaches useable, the reports are generally fairly good. My main spot is the furthest away and does have hills to the NE and Arran to the NW so northerlies can be quite different, eastelries are pants anyway and can be different. Our spot is more open to the south so southerlies are often better than predicted. In fact it is often the case that there is a couple of mph more on the beach than at the airport, even when at Troon, where the kitesurf boundary is the controlled zone for the airport......

 

Mostly I look through loads of forecasts and some charts to make an educated guess and then check xc to see if it agrees at all. Other options are phoning shops at my local spots, one has a good view of trees but being on an industrial estate can't guess the direction, another looks over the beach and can judge everything by what people are flying

 

JIM

[Mr Jo Macdonald]

Hi Boater, where do you kite on the cost, I grew up (a little ) in Saltcoats

What's the kitin like up there?

[8015]

Hi Jo,

I mainly fly at Stevenston, using the beach park and the beach that runs down to Irvine. The beach between Stevenston and Saltcoats we are supposed to leave alone for the nature, and we apparantly have to steer around some rare species of gorse, but who in their right mind buggies or boards through gorse?

 

Stevenston needs mostly west maybe a little south to buggy on the beach because it's quite narrow, anything west is possible for surfing but there is an embankment, mostly concrete, so I don't go out there in dead onshore - it is near perfect in NW as I can drift downwind all the way to Irvine before packing up (considering placing a car in Irvine until we get the hang of going upwind!).

The best places on the west coast (mainland) for kitesurfing are Troon and Barassie, which are just a bit further down. again westerlies, but the beaches curve in opposite directions giving quite a good choice of directions. The best thing is that the Mull of Kintyre stops the big waves so it never gets very rough on the firth of clyde (or when it does you really don't want to be at macrihanish!). I still haven't flown at Irvine, which is where my club originally formed until they moved to stevenston to avoid pedestrians! The beach park at Irvine is supposed to be bigger, and the beach much the same, so apart from ricky outcrops, river mouths and Troon harbour, there would probably be around 10 miles of similar beaches end to end, on the same sweep of coast, in fact if the airport wasn't there we could probably go right past Prestwick and on towards Ayr!

 

Shame the beaches aren't big enough for buggy racing and we have to trek down to England for that. And then you get people complaining about one of the best beaches in the country being closed for a race weekend, well they are welcome to come and play on my beaches whilst I'm on theirs very occasionally!

 

JIM

[Mr Jo Macdonald]

Thanks Jim, sounds good, apart from the gorse traps

 

[rasga]

Maybe if places used TAF data as well as METAR data you could get the 9 and 18 hour forcast trend too

[SandMonster]

There are also some amateur? packet radio stations that transmit weather data...anyone know about the accuracy / reliability of these...???

 

Eg http://www.findu.com/cgi-bin/wxpage.cgi?CW1066

[mspenz]

Point your WAP browsers to;

 

www.activitae.com/wx.wml

 

Search for your icao code , do some research on the forecasting codes and you have a pretty reasonable 12 / 24 hour forecast !

Can't predict sea breezes though , that's up to you.