Weather
- Thread starter Csail
- Start date
1937rogerdon
Member
Interesting site, unfortunately it does not reflect the conditions you will find in the channel when a sea breeze kicks in.
I have little confidence in the met office inshore forecasts,they have been so wrong this year. Perhaps the best choice is to go round a number of site and use the one you like best.
I have little confidence in the met office inshore forecasts,they have been so wrong this year. Perhaps the best choice is to go round a number of site and use the one you like best.
bluedragon
Active member
The problem with the Inshore Waters forecast is the area it covers. We've been in Milford Haven for the past few weeks (still are) and it's been fairly accurate. However, it doesn't reflect the Bristol Channel very well much of the time. In fact most of the forecasts we see on online are too coarse in their resolution to take account of local geography and variations, and are computer generated rather than by a human. The only ones I find that actually differentiate between say the Culver Sand and Cardiff Bay, and reasonably forecast sea breeze are the high res. models accessed by Windguru Pro and Theyr.net...but they are subscription based..not free. The cost is peanuts though for what you get.
PS - here's an example of the Winguru Pro MM5 9km res. map for 14:00 today. The data is also available in tabular form.
And from Theyr.net...
Personally I subscribe to Windguru Pro and can access the tables on a mobile phone browser. So I read the Met Office forecast first, then check actual data on XC Weather, then use Windguru for local forecast variations every two hours for the day(s) ahead.
PS - here's an example of the Winguru Pro MM5 9km res. map for 14:00 today. The data is also available in tabular form.
And from Theyr.net...
Personally I subscribe to Windguru Pro and can access the tables on a mobile phone browser. So I read the Met Office forecast first, then check actual data on XC Weather, then use Windguru for local forecast variations every two hours for the day(s) ahead.
Anwen
Member
Firstly, a belated hello to all in the Bristol Channel. I only noticed this part of the forum yesterday. We moved our Jeanneau SO32 from Plymouth to Swansea last year, and are still getting the hang of things. No trips away yet, although if the weather improves next weekend, we will try and go to either Cardiff or Tenby.
I agree with you - the met office inshore waters forecast is worse than useless most of the time for the channel east of Swansea. I have found that Accuweather is pretty good, as it gives a Mumbles Head forecast, which I think is still computer generated, but is a bit more specific. Here's an example
I also look on XCweather to get a better idea of the wind forecast, and between all of them decide whether to have a go or not. SWMBO doesn't do sea states worse than moderate, so I need to be reasonably sure!
EDIT. Just checked the post and for some reason, the image is a lot smaller than the source file on Photobucket. Not sure how to correct, but hopefully you catch the drift!
I agree with you - the met office inshore waters forecast is worse than useless most of the time for the channel east of Swansea. I have found that Accuweather is pretty good, as it gives a Mumbles Head forecast, which I think is still computer generated, but is a bit more specific. Here's an example
I also look on XCweather to get a better idea of the wind forecast, and between all of them decide whether to have a go or not. SWMBO doesn't do sea states worse than moderate, so I need to be reasonably sure!
EDIT. Just checked the post and for some reason, the image is a lot smaller than the source file on Photobucket. Not sure how to correct, but hopefully you catch the drift!
bluedragon
Active member
Welcome! Don't get me started on sea states... /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif That's the most useless part of the whole IW forecast. I can only assume the terms were derived for super-tankers. For us small craft in the Bristol Channel: Smooth = may be OK; Slight = uncomfortable; Moderate = rough enough that you wish you'd stayed at home; Rough - don't even think about it!! We had inshore waters forecasts last week that had winds of F5 and above and sea state "slight"...how logical is that!! Very misleading terminology IMHO. Here's the definitions:
Smooth: Wave height less than 0.5 m
Slight: Wave height of 0.5 to 1.25 m
Moderate: Wave height of 1.25 to 2.5 m
Rough: Wave height of 2.5 to 4.0 m
In our waters with their tides, overfalls, sands and headlands, 1.00m waves feel like a lot more if short and steep. "moderate" seas of up to 2.5m (>8ft) are bad news. Three of us left Tenby two weeks back with a SW4 occ. 5 against spring tide, destination Milford. The Met office forecast was "slight". Even allowing 2-3 miles off St Govans and Linney Pt we had a very rough ride. A Moody 38 off our beam was doing no better than our 27 footer...so it's not just a boat size issue. The wave train going into the Haven against the ebb would have done justice to Waikiki beach! I checked the wave height at Turbot Bank buoy...at that time it read 3.9ft = slight. Don't ask me how they measure this stuff, but "slight" it wasn't!!
Smooth: Wave height less than 0.5 m
Slight: Wave height of 0.5 to 1.25 m
Moderate: Wave height of 1.25 to 2.5 m
Rough: Wave height of 2.5 to 4.0 m
In our waters with their tides, overfalls, sands and headlands, 1.00m waves feel like a lot more if short and steep. "moderate" seas of up to 2.5m (>8ft) are bad news. Three of us left Tenby two weeks back with a SW4 occ. 5 against spring tide, destination Milford. The Met office forecast was "slight". Even allowing 2-3 miles off St Govans and Linney Pt we had a very rough ride. A Moody 38 off our beam was doing no better than our 27 footer...so it's not just a boat size issue. The wave train going into the Haven against the ebb would have done justice to Waikiki beach! I checked the wave height at Turbot Bank buoy...at that time it read 3.9ft = slight. Don't ask me how they measure this stuff, but "slight" it wasn't!!
Csail
N/A
We left Swansea with THEIR forecast but it was massive out by Nash. Called Swansea for an actual and they said 'slight' (bear in mind they were overlooking the area i was in!) We turned back!
No idea where they get their info from. My method seems to work.......go outside and look.
No idea where they get their info from. My method seems to work.......go outside and look.
bluedragon
Active member
I wonder if Swansea CG actually looked out the window, or compiled reports coming in from vessels in the area?? I suspect they just churn-out the stuff on their latest IW Forecast. Maybe to do anything different would leave them open to litigation in the case of an incident!! Basically we've got to be our own forecasters...and wind on its own is rarely the issue - it's all down to sea state in the end, and where do you get an accurate forecast of that? Nowhere it seems...
1937rogerdon
Member
Perhaps Swansea CG check the weather from the Lee side.
