Inshore weather forecast somewhat deceptive.

[Mataji]

Went from Rothesay to Tarbert yesterday. The inshore forecast for the area Mull of Galloway to Mull of Kintyre including the Firth of Clyde and the North Channel gave, at both 06:00 and 12:00, force 5 to 6. We set off from Rothesay at 11:00 and before we reached the Kyles had already seen 39 knots true wind. Apart from some brief spells when the wind dropped to 15 kn. in the Kyles, we had between 20 and 40 knots all the way. Was mostly around 30 knots but did get 41 in Loch Fyne.

Today the inshore forecast at 12:00 is giving 5 to 7 for the same area, and yet the general Met Office forecast for Rothesay is showing gusts of over 40 mph all afternoon.

I have always thought that the winds in this area would be stronger around the North Channel than the route we took and did not expect the strength of wind we met in our relatively sheltered passage. I am also a little puzzled by today's prediction of 5 to 7 when the forecast for Rothesay is gusts of 40 to 44 mph.

 

[Spyro]

Went from Rothesay to Tarbert yesterday. The inshore forecast for the area Mull of Galloway to Mull of Kintyre including the Firth of Clyde and the North Channel gave, at both 06:00 and 12:00, force 5 to 6. We set off from Rothesay at 11:00 and before we reached the Kyles had already seen 39 knots true wind. Apart from some brief spells when the wind dropped to 15 kn. in the Kyles, we had between 20 and 40 knots all the way. Was mostly around 30 knots but did get 41 in Loch Fyne.


Today the inshore forecast at 12:00 is giving 5 to 7 for the same area, and yet the general Met Office forecast for Rothesay is showing gusts of over 40 mph all afternoon.

I have always thought that the winds in this area would be stronger around the North Channel than the route we took and did not expect the strength of wind we met in our relatively sheltered passage. I am also a little puzzled by today's prediction of 5 to 7 when the forecast for Rothesay is gusts of 40 to 44 mph.

I never believe any forecast North of the Wee Cumbrae it has it's own micro climate. The east kyle is the only place I've seen boats with spinnakers heading toward each other.
I sailed out of Rothesay harbour on Tues morn as well with gusts from the North up to about 25 knots, By the time I had turned the corner and got down to Ascog bay it had gone to the south west and was between 5 and 25 knots. As I . As I passed the light house on the Wee Cumbrae my boatspeed was down to about 3 knots as I wallowed around in a big messy swell, The tower at Ardrossan was speaking to the Arran ferry and saying the wind was still blowing over 20 knots. It's been very odd conditions over the last few days.
I tend to use www.Windguru.cz and select Largs or Ardrossan. It seems the most accurate. Inshore waters forecast for the North clyde is just a waste of time.

 

[[70521]]

Why is it deceptive?

The forecast is written by a group of very nice people sat about 2nm from me. It is based on a whole bunch of numbers and very, very big computers and is the starting point for you to work out what is going on. Always apply your own local knowledge to what the science is telling the forecaster - long gone are the days that they had local forecasters who you could ring and speak to somebody who understood the local factors.

 

[Sgeir]

Today the inshore forecast at 12:00 is giving 5 to 7 for the same area, and yet the general Met Office forecast for Rothesay is showing gusts of over 40 mph all afternoon.

Wouldn't you expect gusts of that strength in a 5-7 forecast?

 

[Mataji]

Wouldn't you expect gusts of that strength in a 5-7 forecast?

The forecast yesterday was 5 to 6. We had 6 to 8 for the whole trip, and were in a relatively sheltered part of the area. I wonder what it was like at the Mull of K.

I know this is a very fickle area. Conditions change quickly and vary considerably throughout the area. But I do find it a bit disturbing that the inshore waters forecast so underestimated the actual wind. (They did get wind direction dead right though).

 

[jonjo]

Wouldn't you expect gusts of that strength in a 5-7 forecast?

Expect gusts of F8 touching F9 given a F5-6 forecast? Nope not expected on my planet.

 

[Bru]

My approach, as a starting point, is that if the Met forecast says F5 to F6, I may get F6 to F7 and there's a chance of F7 to F8

That's not a criticism of the forecasters, it's a realistic nod to the unpredictability of the weather

If it's going to be gusty, another notch or two on the Beaufort scale can be added in the gusts

So heading out into a forecast F6 on a gusty day, I wouldn't be all that surprised to see 30 odd knots of wind rather than 22 to 27 and up into the high 30s in the gusts

And I'd be prepared for the outside chance of seeing high 30s with gusts over, possibly well over, 40 knots

Obviously if a hurricane then rolled in I'd be slightly peeved

I'd be looking at trends too of course. If all the models are predicting improving conditions over the next 24 to 48 hours, the wind speed is far less likely to be significantly higher than forecast for example.

And then local factors come into play. Around my stomping ground the sea breeze can, PM occasions, add or subtract a couple of notches on the scale by the afternoon as well as changing the wind direction dramatically

Oh and I must say that so far this year, my long term criticism of the Met Office over-forecasting wind speeds seems to be outdated. They've been pretty damn close on every occasion I've had cause to look

 

[john_morris_uk]

I'm not convinced that the OP saw Force 8.

F8 is 34 -40 knots average true, not gusts apparent.

I would be interested to hear of how he measured the wind, which direction it was coming relative to the boats motion and whether his instruments can measure true and apparent. (You need an accurate working log integrated into the system for the latter...)

Furthermore it's usual to see gusts at least one up the scale (and depending on the situation it may be two) so to have a true F8 you would perhaps be seeing gusts of 50 knots.

As others have said, don't be too hasty to cast aspersions at the Met office. You need to be aware of local conditions and effects. That's why they also give you an overall picture of the air masses and movements and associated fronts at the beginning of the forecast, together with actual reports from coastal stations etc.

 

[john_morris_uk]

Wouldn't you expect gusts of that strength in a 5-7 forecast?

Completely agree. A 40 mph gust is top of a F7 or just into F8. Exactly what you'd expect for a forecast of F6-7.

 

[MM5AHO]

I've also seen spinnakers approaching each other in east Kyle, then get confused when they meet and the wind changes 180 degrees!

 

[john_morris_uk]

I've also seen spinnakers approaching each other in east Kyle, then get confused when they meet and the wind changes 180 degrees!

Yep!

 

[dom]

I personally find the Inshore Forecast a bit of a joke; a great product no doubt in the days of yore: smoke signals from teepees, Navtex and all that, but in the the 4G era?

The shipping forecast is of course a nice piece of nostalgia when sitting in a big knitted jumper beside a fire with a whiskey in hand (if only I had just one of those things), especially when read by someone with a wonderful voice. But if one is seriously going sailing, all this "gales, soon, later, good, occasionally moderate in the west" stuff ....seriously

Say one is going to Alderney, think of all the extra dets in the French forecast: wind, swell, tot wave height, etc and all filled out for every 6 hr period for the next 4 days http://www.meteofrance.com/previsions-meteo-marine/cotes/cote-ouest-cotentin/0036300

Now take a look at the granularity of the Meteo France forecasts: http://www.meteofrance.com/previsions-meteo-marine/cotes

Come on Met !!!

 

[dimdav]

I tend to use www.Windguru.cz and select Largs or Ardrossan. It seems the most accurate. Inshore waters forecast for the North clyde is just a waste of time.

Totally agree with this however on the Clyde even windguru get the strength wrong if its an easterly.

 

[Sgeir]

Expect gusts of F8 touching F9 given a F5-6 forecast? Nope not expected on my planet.

You misquoted me. Gusts of 40kts are not unusual in forecast 5-7 (not 5-6 as you wrote) - just my observation of sailing mainly off Scotland and Ireland.

As it happens, I do think that the winds (consistent winds rather than gusts) have tended to be slightly stronger than forecast during the recent volatile weather. We're presently in the the south of England and all of the forecasts here (Met Office, XC, YR, WindGuru and the GRIB files) recently seemed to underestimate average strength. I guess that it is not always precisely possible to estimate how Atlantic lows behave.

 

[jonjo]

Say one is going to Alderney, think of all the extra dets in the French forecast: wind, swell, tot wave height, etc and all filled out for every 6 hr period for the next 4 days http://www.meteofrance.com/previsions-meteo-marine/cotes/cote-ouest-cotentin/0036300

I have concluded the British Coastguard has an organizational self death wish.

When a local school or hospital is threatened with closure, people protest. When a coastguard station is for the chop is anyone bothered? The answer is no because they provide such a minimal service. I recall sailing into Irish waters for the first time and hearing actual wind readings in their equivalent of the morning VHF weather report from the coastguard. Why doesn't our Castguard do the same to try and engender some public appreciation and support?

 

[Sgeir]

I have concluded the British Coastguard has an organizational self death wish.

When a local school or hospital is threatened with closure, people protest. When a coastguard station is for the chop is anyone bothered? The answer is no because they provide such a minimal service. I recall sailing into Irish waters for the first time and hearing actual wind readings in their equivalent of the morning VHF weather report from the coastguard. Why doesn't our Castguard do the same to try and engender some public appreciation and support?

Don't the reports from coastal stations do the same thing here? Perhaps the Irish reports are more frequent though.

 

[asteven221]

I am a Clyde man too, and the thing that I find odd is that the Inshore weather forecast, does not agree with the hour to hour forecast from the Met Office web site for the same area, nor the BBC forecast that's provided to them by the Met Office. Why? They are all the same times covering the same place!

You would think in this day and age, with their massive budget and state of art computers, they could provide much better hour to hour forecasts.

Out of interest I Just looked at the Inshore Forecast for the Clyde area. South or southwest "or" being that they are not sure. 4 or 5 - another "or" - seems they are still not sure again, occasionally 6, then becoming 3. So take yer pick.

Following 24 hour outlook - Variable 2 or 3 (or again) then north or northeast, 4 or 5 occasionally 6. So they reckon it's going to be a 2 to a 6, Variable and the north or perhaps northeast.

What use is that to anyone? They would as well saying "the forecast today will be somewhere between nice and calm and blowing old boots and it will be coming from somewhere in the sky"

 

[Spyro]

What use is that to anyone? They would as well saying "the forecast today will be somewhere between nice and calm and blowing old boots and it will be coming from somewhere in the sky"

I usually find it's coming from somewhere I want to go.

 

[john_morris_uk]

I usually find it's coming from somewhere I want to go.

There are some who would suggest that you are going the wrong way in that case...

 

[john_morris_uk]

I am a Clyde man too, and the thing that I find odd is that the Inshore weather forecast, does not agree with the hour to hour forecast from the Met Office web site for the same area, nor the BBC forecast that's provided to them by the Met Office. Why? They are all the same times covering the same place!

You would think in this day and age, with their massive budget and state of art computers, they could provide much better hour to hour forecasts.

Out of interest I Just looked at the Inshore Forecast for the Clyde area. South or southwest "or" being that they are not sure. 4 or 5 - another "or" - seems they are still not sure again, occasionally 6, then becoming 3. So take yer pick.

Following 24 hour outlook - Variable 2 or 3 (or again) then north or northeast, 4 or 5 occasionally 6. So they reckon it's going to be a 2 to a 6, Variable and the north or perhaps northeast.

What use is that to anyone? They would as well saying "the forecast today will be somewhere between nice and calm and blowing old boots and it will be coming from somewhere in the sky"

I suspect it's because the inshore forecast covers such a wide and diverse area, whereas when you look up 'Rothsay' you are looking up a particular place and they can be more specific.